**AEGIS-K code for linear kinetic analysis of toroidally axisymmetric plasma stability**

L.J. Zheng, M.T. Kotschenreuther, and J.W. Van Dam

**Abstract**

A linear kinetic stability code for tokamak plasmas: AEGIS-K (Adaptive EiGenfunction Independent Solutions-Kinetic), is described. The AEGIS-K code is based on the newly developed gyrokinetic theory [L.J. Zheng, M.T. Kotschenreuther, J.W. Van Dam, Phys. Plasmas 14 (2007) 072505]. The success in recovering the ideal magnetohydrodynamics (MHD) from this newly developed gyrokinetic theory in the proper limit leads the AEGIS-K code
to be featured by being fully kinetic in essence but hybrid in appearance. The radial adaptive shooting scheme based on the method of the independent solution decomposition in the MHD AEGIS code [L.J. Zheng, M.T. Kotschenreuther, J. Comp. Phys. 211 (2006) 748] is extended to the kinetic calculation. A numerical method is developed to solve the gyrokinetic equation of lowest order for the response to the independent solutions of the electromagnetic perturbations, with the quasineutrality condition taken into account. A transform
method is implemented to allow the pre-computed Z-function (i.e., the plasma dispersion function) to be used to reduce the integration dimension in the moment calculation and to assure the numerical accuracy in determining the wave–particle resonance effects. Periodic boundary condition along the whole banana orbit is introduced to treat the trapped particles, in contrast to the usual reflection symmetry conditions at the banana tips. Due to the adaptive feature, the AEGIS-K code is able to resolve the coupling between the kinetic resonances and the shear Alfvén continuum damping. Application of the AEGIS-K code to compute the resistive wall modes in ITER is discussed.* © 2010 Elsevier Inc.*

**Current-interchange tearing modes: Conversion of interchange-type modes to tearing modes**

L.J. Zheng and M. Furukawa

**Abstract**

It is shown that, in addition to usual neoclassical tearing modes, another type of nonclassical tearing
mode exists in tokamaks: viz., current-interchange tearing modes (CITMs). CITMs are directly
driven by unstable pressure-driven electromagnetic or electrostatic modes of the interchange type
(e.g., interchange/ballooning modes, drift waves, etc.) due to the current gradient in tokamaks.
Interchange-type modes exchange not only thermal and magnetic energies between flux tubes but
also current. In a plasma with a current (or resistivity) gradient, such an interchange can create a
current sheet at a mode resonance surface and result in the excitation of CITMs. Note that the
interchange mode (i.e., Rayleigh–Taylor instability) is fundamental to tokamak physics. This new
theory has an effect on both resistive magnetohydrodynamic stability and transport theories.
Instabilities of the interchange type could be directly converted into CITMs, alternative to forming
turbulent eddies through nonlinear coupling as in conventional transport theories. In particular, our CITM theory fills in the component in the transport theory of Rechester and Rosenbluth [Phys. Rev.
Lett. **40**, 38 (1978)] for the origin of magnetic island structure in axisymmetric tokamaks. © *2010 American Institute of Physics*

**Generalized two-fluid equilibria: Understanding RT-1 experiments and beyond**

Z. Yoshida, S.M. Mahajan, T. Mizushima, Y. Yano, H. Saitoh, and J. Morikawa

**Abstract**

Diversity of plasma structures, which degenerates in the ideal magnetohydrodynamic model, can
emerge in many ways in a two-fluid plasma endowed with a hierarchy of scales. We study the
equilibrium structure of high-beta (high temperature and low-density) electrons in a relatively weak
magnetic field. Spontaneous flow generation and strong diamagnetism are clear manifestations of
the nonideal two-fluid dynamics scaled, respectively, by the ion and electron-inertia lengths (skin
depths). The theory predicts stronger flow and diamagnetism in the nonlinear regime of the two-fluid
dynamics.* © 2010 American Institute of Physics*

**Nonlinear dynamics of the electromagnetic ion cyclotron structures in the inner magnetosphere**

N.L. Tsintsadze, T.D. Kaladze, J.W. Van Dam, W. Horton, X.R. Fu, and T.W. Garner

**Abstract**

Electromagnetic ion cyclotron waves, called EMICs, are widely observed in the inner
magnetosphere and can be excited through various plasma mechanisms such as ion
temperature anisotropy. These waves interact with magnetospheric particles, which they
can scatter into the loss cone. This paper investigates how nonlinearities in the ion
fluid equations governing the electromagnetic ion cyclotron waves cause large-amplitude
EMIC waves to evolve into coherent nonlinear structures. Both planar soliton structures
and also two-dimensional vortex-like nonlinear structures are found to develop out of
these nonlinearities. © *2010 The American Geophysical Union*

**Gyrofluid simulations of collisionless reconnection in the presence of diamagnetic effects**

E. Tassi, F.L. Waelbroeck, and D. Grasso

**Abstract**

The effects of the ion Larmor radius on magnetic reconnection are investigated by means
of numerical simulations, with a Hamiltonian gyrofluid model. In the linear regime, it is found
that ion diamagnetic effects decrease the growth rate of the dominant mode. Increasing ion
temperature tends to make the magnetic islands propagate in the ion diamagnetic drift direction.
In the nonlinear regime, diamagnetic effects reduce the final width of the island. Unlike the electron density, the guiding center density does not tend to distribute along separatrices and
at high ion temperature, the electrostatic potential exhibits the superposition of a small scale
structure, related to the electron density, and a large scale structure, related to the ion guidingcenter
density. *© 2010 IOP Publishing Ltd*

DOI:10.1088/1742-6596/260/1/012020

**Hamiltonian four-field model for magnetic reconnection: nonlinear dynamics and extension to three dimensions with externally applied fields**

E. Tassi, P.J. Morrison, D. Grasso, and F. Pegoraro

**Abstract**

The nonlinear dynamics of a two-dimensional (2D) model for collisionless magnetic reconnection is investigated
both numerically and analytically. For very low values of the plasma *β*, parallel magnetic perturbations tend to
be proportional to the vorticity perturbations, but as *β* increases, detachment of these quantities takes place. The
subsequent difference between the structure of the vorticity and the parallel magnetic perturbations can be explained naturally in terms of the ‘normal’ field variables that emerge from the noncanonical Hamiltonian theory of the model.
A three-dimensional extension of the reconnection model is also presented, its Hamiltonian structure is derived, and
the corresponding conservation properties are compared with those of the 2D model. A general method for extending
a large class of 2D fluid plasma models to three dimensions, while preserving the Hamiltonian structure, is then
presented. Finally, it is shown how such models can also be extended, while preserving the Hamiltonian structure,
to include externally applied fields, that can be used, for instance, for modelling resonant magnetic perturbations. © *2010 IAEA, Vienna*

DOI:10.1088/0029-5515/50/3/034007

**Quasi-linear MHD modelling of H-mode plasma response to resonant magnetic perturbations**

E. Nardon, P. Tamain, M. Bécoulet, G. Huysmans, and F.L. Waelbroeck

**Abstract**

The plasma response to externally imposed resonant magnetic perturbations (RMPs) is investigated through
quasi-linear MHD modelling in the case where the resonant surfaces are located in the pedestal of an H-mode
plasma. The pedestal is a particular region regarding the question of plasma response to RMPs because of its strong
*E* × *B* and electron diamagnetic rotations. It is found that a strong rotational screening takes place in most of the
pedestal. The RMPs may, however, penetrate in a narrow layer at the very edge, where the plasma is cold and
resistive. The possibility that one harmonic of the RMPs may also penetrate if its resonant surface is at a particular
location, close to the top of the pedestal, where the *E*×*B* and electron diamagnetic rotations compensate each other,
is discussed. Finally, the RMPs are found to produce some additional transport, even though they do not penetrate. *© 2010 IAEA, Vienna*

DOI:10.1088/0029-5515/50/3/034002

**Formation of coherent vortex streets and transport reduction in electron temperature gradient driven turbulence**

M. Nakata, T.-H. Watanabe, H. Sugama, and W. Horton

**Abstract**

Vortex structures in slab electron temperature gradient (ETG) driven turbulence are investigated by
means of a gyrokinetic simulation with high phase-space resolution. Depending on parameters that
determine the eigenfrequency of the linear ETG modes, two different flow structures, i.e.,
statistically steady turbulence with a weak zonal flow and coherent vortex streets along a strong
zonal flow, are observed. The former involves many isolated vortices and their mergers with
complicated motion and leads to steady electron heat transport. When the latter is formed, phase
difference and high wavenumber components of potential and temperature fluctuations are reduced,
and the electron heat transport decreases significantly. It is also found that the phase matching with
the potential fluctuation is correlated with the reduction in the imaginary part of the perturbed
distribution function, and it occurs not only for the temperature fluctuation but also for any nth
velocity moments. A traveling wave solution of a Hasegawa–Mima type equation derived from the
gyrokinetic equation with the ETG agrees well with the coherent vortex streets found in the slab
ETG turbulence. © *2010 The American Institute of Physics*

**Integrable maps with non-trivial topology: application to divertor configurations**

T. Kroetz, M. Roberto, I.L. Caldas, R.L. Viana, P.J. Morrison, and P. Abbamonte

**Abstract**

We explore a method for constructing two-dimensional area-preserving, integrable maps associated with Hamiltonian
systems, with a given set of fixed points and given invariant curves. The method is used to find an integrable Poincaré
map for the field lines in a large aspect ratio tokamak with a poloidal single-null divertor. The divertor field is a
superposition of a magnetohydrodynamic equilibrium with an arbitrarily chosen safety factor profile, with a wire carrying an electric current to create an *Χ*-point. This integrable map is perturbed by an impulsive perturbation that
describes non-axisymmetric magnetic resonances at the plasma edge. The non-integrable perturbed map is applied
to study the structure of the open field lines in the scrape-off layer, reproducing the main transport features obtained
by integrating numerically the magnetic field line equations, such as the connection lengths and magnetic footprints
on the divertor plate. *© 2009 IAEA, Vienna*

DOI:10.1088/0029-5515/50/3/034003

**Angular redistribution of nonlinear perturbations: A universal feature of nonuniform flows**

W. Horton, J.-H. Kim, G.D. Chagelishvili, J.C. Bowman, and J.G. Lominadze

**Abstract**

Classically, the net action of nonlinear turbulent processes is interpreted as either a direct or inverse cascade.
However, in nonuniform/shear flows the dominant process is a nonlinear redistribution over wave number
angle of perturbation spatial Fourier harmonics. We call this process a *nonlinear transverse redistribution* (NTR). This phenomenon is demonstrated for a simple two-dimensional constant shear (non-normal) flow by
numerically simulating the nonlinear dynamics of coherent and stochastic vortical perturbations in the flow.
NTR is a general feature of nonlinear processes that should manifest itself in nonuniform engineering, environmental, and astrophysical flows. The conventional characterization of turbulence in terms of direct and
inverse cascades, which ignores NTR, appears to be misleading for shear flow turbulence. We focus on the
action of nonlinear processes on the spectral energy. NTR redistributes perturbations over different quadrants
of the wave number plane and the interplay of this nonlinear redistribution with linear phenomena becomes
intricate: it can realize either positive or negative feedback. In the case of positive feedback, it repopulates the
quadrants in wave number space where the shear flow induces linear transient growth. © *2010 The American Physical Society*

DOI:10.1103/PhysRevE.81.066304

**Laser experiments to simulate coronal mass ejection driven magnetospheres and astrophysical plasma winds on compact magnetized stars**

W. Horton, T. Ditmire, and Y.P. Zakharov

**Abstract**

Laboratory experiments using a plasma wind generated by laser-target interaction are proposed to investigate the creation of a shock in front of the magnetosphere and the dynamo mechanism for creating plasma currents and voltages. Preliminary experiments are shown where measurements of the electron density gradients surrounding the obstacles are recorded to infer the plasma winds. The proposed experiments are relevant to understanding the electron acceleration mechanisms taking place in shock-driven magnetic dipole confined plasmas surrounding compact magnetized stars and planets. Exploratory experiments have been published [P. Brady, T. Ditmire, W. Horton, et al., Phys. Plasmas 16, 043112 (2009)] with the one Joule Yoga laser and centimeter sized permanent magnets. *© 2009 Elsevier B.V.*

DOI:10.1016/j.hedp.2009.12.001

**IFSR-1360**

**Plasma Display**

R. Hazeltine, M. Porkolab, S. Prager, and R. Stambaugh

**Abstract**

Michael Moyer's "Fusion's False Dawn" might give the impression that informed scientists have become skeptical about fusion. This impression is incorrect. Fusion scientists consider their goal to be more tractable and relevant than ever before- and every one of several recently commissioned expert review committees has concurred, concluding that fusion energy should be actively pursued. Magnetic fusion devices have already in 1997 produced 16 million watts of fusion power. The challenges of plasma physics have been sufficiently met that we can confidently design devices that will make copious fusion reactions. ITER is one such device that will enable study of high-energy-gain plasma physics. Fusion researchers worldwide are discussing facilities from specialized experiments to a demonstration power plant to take on our next issues of materials, power extraction and tritium production in a reliable, continuously operating system.© *2010 Scientific American*

DOI:10.1038/scientificamerican0710-10

**Research needs workshop for magnetic fusion energy science**

R.D. Hazeltine

**Abstract**

The process, organization, and results of the Research Needs Workshop for Magnetic Fusion Energy Science
are reviewed, and the Workshop Report is briefly surveyed. © *2010 Elsevier B.V.*

DOI:10.1016/j.fusengdes.2009.12.007

**On Krein-like theorems for noncanonical Hamiltonian systems with continuous spectra: application to Vlasov-Poisson**

G.I. Hagstrom and P.J. Morrison

**Abstract**

The notions of spectral stability and the spectrum for the Vlasov-Poisson system
linearized about homogeneous equilibria, ƒ_{0}(*ν*), are reviewed. Structural stability
is reviewed and applied to perturbations of the linearized Vlasov operator
through perturbations of ƒ_{0}. We prove that for each ƒ_{0} there is an arbitrarily small δ *f´*_{0} in *W*^{1,1}(ℝ) such that ƒ_{0} + δ ƒ_{0} is unstable. When ƒ_{0} is perturbed
by an area preserving rearrangement, ƒ_{0} will always be stable if the continuous spectrum is only of positive signature, where the signature of the continuous
spectrum is defined as in Morrison and Pfirsch (1992) and Morrison (2000). If there is a signature change, then there is a rearrangement of ƒ_{0} that is unstable
and arbitrarily close to ƒ_{0} with *f´*_{0} in W.^{1,1} This result is analogous to Krein’s theorem for the continuous spectrum. We prove that if a discrete mode embedded
in the continuous spectrum is surrounded by the opposite signature there is an
infinitesimal perturbation in C^{n} norm that makes ƒ_{0} unstable. If ƒ_{0} is stable we
prove that the signature of every discrete mode is the opposite of the continuum
surrounding it. © *2010 Taylor & Francis Group, LLC*

DOI:10.1080/00411450.2011.566484

**Nonlinear gyrofluid simulations of collisionless reconnection**

D. Grasso, E. Tassi, and F.L. Waelbroeck

**Abstract**

The Hamiltonian gyrofluid model recently derived by Waelbroeck *et al*. [Phys. Plasmas **16**, 032109
(2009)] is used to investigate nonlinear collisionless reconnection with a strong guide field by means
of numerical simulations. Finite ion Larmor radius gives rise to a cascade of the electrostatic
potential to scales below both the ion gyroradius and the electron skin depth. This cascade is similar
to that observed previously for the density and current in models with cold ions. In addition to
density cavities, the cascades create electron beams at scales below the ion gyroradius. The presence
of finite ion temperature is seen to modify, inside the magnetic island, the distribution of the velocity
fields that advect two Lagrangian invariants of the system. As a consequence, the fine structure in
the electron density is confined to a layer surrounding the separatrix. Finite ion Larmor radius
effects produce also a different partition between the electron thermal, potential, and kinetic energy,
with respect to the cold-ion case. Other aspects of the dynamics such as the reconnection rate and the stability against Kelvin–Helmholtz modes are similar to simulations with finite electron
compressibility but cold ions. © *2010 American Institute of Physics*

**A drift-magnetohydrodynamical fluid model of helical magnetic island equilibria in the pedestals of H-mode tokamak plasmas**

R. Fitzpatrick and F.L. Waelbroeck

**Abstract**

A drift-magnetohydrodynamical (MHD) fluid model is developed for an isolated, steady-state,
helical magnetic island chain, embedded in the pedestal of a large aspect ratio, low-*β*, circular cross
section, H-mode tokamak plasma, to which an externally generated, multiharmonic, static magnetic
perturbation whose amplitude is sufficiently large to fully relax the pedestal toroidal ion flow is
applied. The model is based on a set of single helicity, reduced, drift- MHD fluid equations which
take into account neoclassical poloidal and toroidal flow damping, the perturbed bootstrap current,
diamagnetic flows, anomalous cross-field diffusion, average magnetic-field line curvature, and
coupling to drift-acoustic waves. These equations are solved analytically in a number of different
ordering regimes by means of a systematic expansion in small quantities. For the case of a freely
rotating island chain, the main aims of the calculation are to determine the chain’s phase velocity,
and the sign and magnitude of the ion polarization term appearing in its Rutherford radial width evolution equation. For the case of a locked island chain, the main aims of the calculation are to
determine the sign and magnitude of the polarization term. © *2010 American Institute of Physics*

**Locked magnetic island chains in toroidally flow damped tokamak plasmas**

R. Fitzpatrick and F.L. Waelbroeck

**Abstract**

The physics of a locked magnetic island chain maintained in the pedestal of
an H-mode tokamak plasma by a static, externally generated, multi-harmonic, helical magnetic perturbation is investigated. The non-resonant harmonics of
the external perturbation are assumed to give rise to significant toroidal flow damping in the pedestal, in addition to the naturally occurring poloidal flow
damping. Furthermore, the flow damping is assumed to be sufficiently strong
to relax the pedestal ion toroidal and poloidal fluid velocities to fixed values
determined by neoclassical theory. The resulting neoclassical ion flow causes a helical phase-shift to develop between the locked island chain and the resonant
harmonic of the external perturbation. Furthermore, when this phase-shift exceeds a critical value, the chain unlocks from the resonant harmonic and
starts to rotate, after which it decays away and is replaced by a helical current sheet. The neoclassical flow also generates an ion polarization current in the
vicinity of the island chain which either increases or decreases the chain’s
radial width, depending on the direction of the flow. If the polarization effect is
stabilizing, and exceeds a critical amplitude, then the helical island equilibrium becomes unstable, and the chain again decays away. The critical amplitude
of the resonant harmonic of the external perturbation at which the island chain either unlocks or becomes unstable is calculated as a function of the pedestal ion
pressure, the neoclassical poloidal and toroidal ion velocities and the poloidal
and toroidal flow damping rates. © *2010 IOP Publishing Ltd*

DOI:10.1088/0741-3335/52/5/055006

**A nonideal error-field response model for strongly shaped tokamak plasmas**

R. Fitzpatrick

**Abstract**

A model is developed that describes the error-field response of a toroidally rotating tokamak plasma
possessing a strongly shaped poloidal cross-section. The response is made up of nondissipative ideal
and dissipative nonideal components. The calculation of the ideal response is greatly simplified by
employing a large aspect-ratio, constant pressure plasma equilibrium in which the current is entirely
concentrated at the boundary. Moreover, the calculation of the resonant component of the nonideal
response is simplified by modeling each resonant surface within the plasma as a toroidally rotating,
thin resistive shell that only responds to the appropriate resonant component of the perturbed
magnetic field. This approach mimics dissipation due to continuum damping at Alfvén and/or sound
wave resonances inside the plasma. The nonresonant component of the nonideal response is
neglected. The error-fields that maximize the net toroidal locking torque exerted on the plasma are
determined via singular value decomposition of the total response matrix. For a strongly dissipative plasma, the locking torque associated with a general error-field is found to peak at a beta value that
lies *above* the no-wall beta-limit, in accordance with experimental observations. © *2010 American Institute of Physics*

**Magnetic reconnection in weakly collisional highly magnetized electron-ion plasmas**

R. Fitzpatrick

**Abstract**

A reduced three-field model of two-dimensional magnetic reconnection in a weakly collisional,
highly magnetized plasma consisting of isothermal electrons and cold ions is derived from a set of
Braginskii-like fluid equations. The model is then used to calculate the linear growth rate of the
reconnecting instability in collisionless and semicollisional parameter regimes. © *2010 American Institute of Physics*

**Derivation of reduced two-dimensional fluid models via Dirac's theory of constrained Hamiltonian systems**

C. Chandre, E. Tassi, and P.J. Morrison

**Abstract**

We present a Hamiltonian derivation of a class of reduced plasma two-dimensional fluid models, an
example being the Charney–Hasegawa–Mima equation. These models are obtained from the same
parent Hamiltonian model, which consists of the ion momentum equation coupled to the continuity
equation, by imposing dynamical constraints. It is shown that the Poisson bracket associated with
these reduced models is the Dirac bracket obtained from the Poisson bracket of the parent model. © *2010 American Institute of Physics*

**Erratum**

H.L. Berk

**Abstract**

Explanation of the JET n = 0 chirping mode
H.L. Berk *et al* 2006 *Nucl. Fusion* **46** S888-S897

Figure 1(a) was repeated in this article, and the correct figure
1(b) was omitted. Below is figure 1 as it should have been
published. © *2010 IAEA*

DOI:10.1088/0029-5515/50/4/049802

**Fast excitation of EGAM by NBI**

H.L. Berk and T. Zhou

**Abstract**

A new mechanism for the fast excitation of the energetic geodesic acoustic mode (EGAM) is proposed to explain
the recent experiment in DIII-D (Nazikian *et al 2008 Phys. Rev. Lett.* **101** 185001), where the mode turns on in
less than a millisecond after the turn-on of the neutral beam injection. The existence of loss boundary in pitch
angle when beam particles are injected counter to the plasma current is crucial to the formation of negative energy
EGAM mode. The resonance of this negative energy wave with energetic particles, whose distribution decreases
with energy, destabilizes the mode. We find that when there is a loss region, the onset time of instability can be
significantly shorter than it would be if the injected particles had no loss region. © *2010 International Atomic Energy Agency*

DOI:10.1088/0029-5515/50/3/035007

**Transport properties in nontwist area-preserving maps**

J.D. Szezech, Jr., I.L. Caldas, S.R. Lopes, R.L. Viana, and P.J. Morrison

**Abstract**

Nontwist systems, common in the dynamical descriptions of fluids and plasmas, possess a shearless
curve with a concomitant transport barrier that eliminates or reduces chaotic transport, even after its
breakdown. In order to investigate the transport properties of nontwist systems, we analyze the
barrier escape time and barrier transmissivity for the standard nontwist map, a paradigm of such
systems. We interpret the sensitive dependence of these quantities upon map parameters by investigating
chaotic orbit stickiness and the associated role played by the dominant crossing of stable
and unstable manifolds. © *2009 American Institute of Physics*

**MHD equilibrium variational principles with symmetry**

T. Andreussi, P.J. Morrison, and F. Pegoraro

**Abstract**

The chain rule for functionals is used to reduce the noncanonical Poisson bracket
for magnetohydrodynamics (MHD) to one for axisymmetric and translationally
symmetric MHD and hydrodynamics. The procedure for obtaining Casimir
invariants from noncanonical Poisson brackets is reviewed and then used to
obtain the Casimir invariants for the considered symmetrical theories. It
is shown why extrema of the energy plus Casimir invariants correspond to
equilibria, thereby giving an explanation for the *ad hoc* variational principles
that have existed in plasma physics. Variational principles for general equilibria
are obtained in this way. © *2010 IOP Publishing Ltd*

DOI:10.1088/0741-3335/52/5/055001

**Rotational stabilization of resistive wall modes in ITER advanced tokamak scenarios**^{a}

L.J. Zheng, M.T. Kotschenreuther, and J.W. Van Dam

**Abstract**

Rotational stabilization of *n*=1 resistive wall modes in ITER advanced scenarios [K. Ikeda, Nucl.
Fusion **47** (2007)] is investigated, where *n* is the toroidal mode number. In particular, we present
numerical results for the ITER strongly reversed shear case, in comparison to the weakly reversed
shear case. The rotation frequency is assumed to be modestly low. Our investigation employs the
adaptive eigenfunction independent solution-kinetic (AEGIS-K) code [L. J. Zheng *et al*., “AEGIS-K
code for linear kinetic analysis of toroidally axisymmetric plasma stability,” J. Comput. Phys. (to be
published)], which provides a fully kinetic (nonhybrid) and self-consistent (nonperturbative)
description. AEGIS-K includes wave-particle resonances, shear Alfvén continuum damping, trapped
particle effects, and parallel electric effects, but not finite Larmor radius effects. In the case without
rotation and kinetic effects included, we find that the strongly reversed shear configuration is more
favorable for perfectly conducting wall stabilization of resistive wall modes, in that it has a higher
conducting wall beta limit than the weakly reversed shear case. With sufficient rotation, the strongly
reversed shear case can also achieve a higher beta limit for completely suppressing the resistive wall
modes. However, the marginal rotation frequency required for complete resistive wall mode
stabilization in the strongly reversed shear case is about twice as high as that required for the weakly
reversed shear case. © *2010 American Institute of Physics*

**Kinetic analysis of the resistive wall modes in the ITER advanced tokamak scenario**

L.J. Zheng, M.T. Kotschenreuther, and J.W. Van Dam

**Abstract**

It is found that *n* = 1 resistive wall modes in the ITER advanced scenario can be fully stabilized by modestly low
rotation with a rotation frequency (normalized to the Alfvén frequency at the magnetic axis) of about Ω = 0.0075.
The existence of this stabilization scheme is proved with the AEGIS-K (Adaptive EiGenfunction Independent
Solution-Kinetic) code, which provides a fully kinetic (non-hybrid) and self-consistent (non-perturbative) description

of the system. Wave-particle resonances, shear Alfvén continuum damping, trapped particle effect and the parallel
electric effects are all taken into account. The rotation frequency for full stabilization is much larger than the
diamagnetic drift frequency; therefore, finite Larmor radius effects are negligible. We also find that the rotation
stabilization window opens first near the ideal wall limit. © *2009 International Atomic Energy Agency*

DOI:10.1088/0029-5515/49/7/07/5021

**Laser-plasma simulations of artificial magnetospher formed by giant coronal mass ejections**

Y.P. Zakharov, A.G. Ponomarenko, K.V. Vchivkov, W. Horton, and P. Brady

**Abstract**

We employed the laboratory (Laser-Produced
Plasmas, LPP) and numerical (3D/PIC-code) simulations to
study the resulting state of very strong compression of magnetopause
(MP) by CME with effective energy E_{0} ≥ 10^{34}
ergs directed to the Earth. During probable formation of an Artificial Magnetosphere (AM, *in a flow of CME’ plasma around the Earth*) with the MP stand-off at R_{mp} up to
(2–3)R_{E}, many catastrophic phenomena could occur in a
space and ground networks due to very high curl electric
fields induced by world-wide magnetic field’s changes with
a SC-rate >50 nT/s. The laboratory models of AM (with
R_{mp} ∼ 0.1–30 cm) were formed around high-field, 1D and
3D magnetic obstacles, overflowing by LPP-blobs with E_{0}
up to kJ and magnetized ions. The shape and internal structure
of a large-scale AM were studied at KI-1 facility of the
Russian team using a set of B-dot magnetic probes, while
the main goal of UT’s small-AM experiment was to explore
a possible shock’s generation and relevant electron acceleration.
Preliminary results of KI-1 experiments show that
the both R_{m}-size and SC (E_{0}) of AM could be described
by modified Chapman-Ferraro Scaling, while the whole SC-distribution
(in front “one-half” of equatorial plane)—by
well-known “Image Dipole” model of the Earth’s magnetopause
field. © *2009 Astrophys Space Sci*

**Variational coordinate transformation in plasma physics**

R.L. White, E.R. Solano, and R.D. Hazeltine

**Abstract**

It is well-known from scaling arguments that action-based field theories do not possess localized
solutions in spaces of more than one dimension. The same scaling argument, modified to account for
external forces, is applied to magnetic plasma confinement in an axisymmetric torus. It yields an
integral solvability condition of some interest. © *2009 American Institute of Physics*

**Symmetry analysis of the Grad-Shafranov equation**

R.L. White and R.D. Hazeltine

**Abstract**

Lie’s technique of computing symmetries of differential equations is applied to a specific case of the
Grad–Shafranov equation. The case considered contains the majority of exact solutions from
literature. The full symmetry group is computed and new group-invariant solutions are obtained
from these symmetries. The basic results and methods behind this technique are given to allow the
reader who is unfamiliar with the subject to use the results given in this paper. Several plots of the
level sets or flux surfaces of the new solutions are given. © *2009 American Institute of Physics*

**Some physical mechanisms of precursors to earthquakes**

J.W. Van Dam, W. Horton, N.L. Tsintsadze, T.D. Kaladze, T.W. Garner, and L.V. Tsamalashvili

**Abstract**

The existence of precursors to earthquakes at different heights of the earth’s ionosphere is investigated. We
analyze a mechanism for the generation of low-frequency large-scale zonal flows by higher frequency, small-scale
internal-gravity waves in the electrically neutral troposphere. The nonlinear generation mechanism is based on
parametric excitation of convective cells by finite amplitude internal-gravity waves. Measured density perturbations
arising due to zonal flow generation may confirm the seismic origin of this mechanism. We also investigate
nonlinear propagation of low-frequency seismic-origin internal-gravity perturbations in the stable stratified
conductive E-layer. The predicted enhancement of atomic oxygen radiation at wavelength 557.7 nm due to the
damping of nonlinear internal-gravity vortices is compared with the observed increase of the night-sky green light
intensity before an earthquake. The good agreement suggests that ionospheric internal-gravity vortices can be
considered as wave precursors of strong earthquakes. These precursors could be a tool for predicting the occurrence of a massive earthquake or volcano. © *2009 The Japan Society of Plasma Science and Nuclear Fusion Research *

**Progress towards burning plasma**

J.W. Van Dam

**Abstract**

The next frontier for fusion science is the study of burning plasmas. The international ITER facility will
advance research efforts into this new regime. In this paper we will first define burning plasmas and describe
their distinctive features. One such feature is dominant self-heating (exothermic) by a large population of alpha
particles, created from thermonuclear reactions. Next, we will briefly review how previous experiments on JET
and TFTR to attain breakeven have laid the foundation for taking the present step to ITER. Then, we will describe
various physics and technology issues that need to be addressed for burning plasmas. In addition to the scientific
opportunities, we will also describe how ITER, being operated as a large-scale international project, is making
progress in terms of organization, mission, funding, and programmatic coordination worldwide. © *2009 The Japan Society of Plasma Science and Nuclear Fusion Research*

**Hamiltonian derivation of the Charney-Hasegawa-Mima equation**

E. Tassi, C. Chandre, and P.J. Morrison

**Abstract**

The Charney–Hasegawa–Mima equation is an infinite-dimensional Hamiltonian system with
dynamics generated by a noncanonical Poisson bracket. Here a first principle Hamiltonian
derivation of this system, beginning with the ion fluid dynamics and its known Hamiltonian form,
is given. © *2009 American Institute of Physics *

**Stability and nonlinear dynamics aspects of a model for collisionless magnetic reconnection**

E. Tassi, D. Grasso, F. Pegoraro, and P.J. Morrison

**Abstract**

A Hamiltonian 4-field fluid model describing magnetic reconnection in collisionless plasmas is investigated
both analytically and numerically. The noncanonical Hamiltonian structure of the model
is used in order to derive equilibrium equations and sufficient conditions for stability of equilibria in
the presence of toroidal flow. Numerical simulations of the model equations are then used in order
to investigate the vorticity evolution in the nonlinear regime. The coexistence of vortex-sheet-like and
filamented structures is observed, which had no counterpart in a previously investigated 2-field model.
Such evolution of the vorticity field is explained using the Casimir functionals of the system. Comments
on the dependence of the vorticity structure on the value of the electron skin depth are also given. © *2009 The Japan Society of Plasma Science and Nuclear Fusion Research*

**Spectrum of global magnetorotational instability in a narrow transition layer**

J. Pino and S.M. Mahajan

**Abstract**

The global magnetorotational instability is investigated for a configuration in which the rotation frequency changes
only in a narrow transition region. If the vertical wavelength of the unstablemode is of the same order or smaller than
the width of this region, the growth rates can differ significantly from those given by a local analysis. In addition,
the nonaxisymmetric spectrum admits overstable modes with a nontrivial dependence on azimuthal wavelength,
a feature missed by the local theory. In the limit of vanishing transition region width, the Rayleigh-centrifugal
instability is recovered in the axisymmetric case, and the Kelvin–Helmholtz instability in the nonaxisymmetric
case. © *2009 The American Astronomical Society*

DOI:10.1088/0004-637X/697/2/1805

**Thoughts on brackets and dissipation: old and new**

P.J. Morrison

**Abstract**

Bracket formulations of two kinds of dynamical systems, called incomplete and complete,
are reviewed and developed, including double bracket and metriplectic dynamics. Dissipation
based on the Cartan-Killing metric is introduced. Various examples of incomplete and complete
dynamics are discussed, including dynamics associated with three-dimensional Lie algebras. © *2009 IOP Publishing Ltd*

DOI:10.1088/1742-6596/169/1/012006

**Linear superposition of nonlinear waves**

S.M. Mahajan and H. Miura

**Abstract**

Exact nonlinear (arbitrary amplitude) wave-like solutions of an incompressible,
magnetized, non-dissipative two-fluid system are found. It is shown that,
in1-D propagation, these fully nonlinear solutions display a rare property; they
can be linearly superposed. © *2008 Cambridge University Press*

**Destabilizing Effect of Dynamical Friction on Fast-Particle-Driven Waves in a Near-Threshold Nonlinear Regime**

M.K. Lilley, B.N. Breizman, and S.E. Sharapov

**Abstract**

The nonlinear evolution of waves excited by the resonant interaction with energetic particles, just above
the instability threshold, is shown to depend on the type of relaxation process that restores the unstable
distribution function. When dynamical friction dominates over diffusion in the phase space region surrounding the wave-particle resonance, an explosive evolution of the wave is found to be the only
solution. This is in contrast with the case of dominant diffusion when the wave may exhibit steady-state,
amplitude modulation, chaotic and explosive regimes near marginal stability. The experimentally
observed differences between Alfve´nic instabilities driven by neutral beam injection and those driven
by ion-cyclotron resonance heating are interpreted. © *2009 The American Physical Society*

DOI:10.1103/PhysRevLett.102.195003

**Plasma transport and turbulence in the Helimak: Simulation and experiment**

B. Li, B.N. Rogers, P. Ricci, and K.W. Gentle

**Abstract**

The Helimak experiment produces a toroidal plasma with a helical magnetic field. A
simulation-experiment comparison of turbulence in this device is presented, focusing on parameter
regimes in which the turbulence is dominated by interchange modes with k_{∥}≃0. The numerical
simulations are based on a two-dimensional electrostatic two-fluid model that evolves the full radial
profiles of plasma density, the electric potential, and the electron temperature. The simulation results
are compared with the experiment and general agreement is found for the plasma profiles, the
autocorrelation functions, the frequency spectra, the cross-correlation functions, and the probability
density functions. Some quantitative differences between the simulation and experimental data are

also discussed. © *2009 American Institute of Physics*

**Fluid models of impurity transport via drift wave turbulence**

S. Futatani, W. Horton, S. Benkadda, I.O. Bespamyatnov, and W.L. Rowan

**Abstract**

Turbulent transport due to drift waves is a critical issue for fusion physics across all magnetic
confinement geometries. Three-component fluid equations are used to find the eigenmodes and
eigenfrequencies of a nonuniform, magnetized plasma with a four dimensional fluctuation vector
composed of fluctuations of the electron density, the working gas ion density, the impurity density,
and the electrostatic plasma potential. This structure of the eigenmodes and eigenvectors is shown
for two collisionality regimes: (*i*) the collisional drift waves appropriate for the scrape-off-layer and
the edge plasma in limiter discharges and (*ii*) the trapped electron mode taken in the limit of a
Terry–Horton fluid description for the core plasma. From the eigenmodes and eigenvectors the part
of the density and potential fluctuations that are out-of-phase is computed. The quasilinear particle
fluxes are analyzed as a function of the power spectrum of the plasma potential fluctuations and the
gradient parameters characterizing the Ohmic, H, and internal transport barrier confinement modes.
A reversal in a direction of impurity flux is observed by changing the sign of the impurity density
gradient length. After reversal, the impurity flux is directed outward and it is a favorable for fusion
plasmas. © *2010 American Institute of Physics*

**A numerical matching technique for linear resistive magnetohydrodynamics modes**

M. Furukawa, S. Tokuda, and L.J. Zheng

**Abstract**

A new numerical matching technique for linear stability analysis of resistive
magnetohydrodynamics (MHD) modes is developed. The solution to the resistive reduced MHD
equations in an inner layer with a finite width is matched onto the solution to the inertialess ideal
MHD or the Newcomb equation by imposing smooth disappearance of parallel electric field in
addition to the continuity of perturbed magnetic field and its spatial gradient. The boundary

condition for the parallel electric field is expressed as a boundary condition of the third kind for the
stream function of the perturbed velocity field. This technique can be applied for the reversed
magnetic shear plasmas of their minimum safety factors being rational numbers, for which the
conventional asymptotic matching technique fails. In addition, this technique resolves practical
difficulties in applying the conventional asymptotic matching technique, i.e., the sensitivity of the
outer-region solution on the accuracy of the local equilibrium as well as the grid arrangements, even
in normal magnetic shear plasmas. Successful applications are presented not only for the eigenvalue
problem but also for the initial-value problem. © *2010 American Institute of Physics*

**Effect of local E×B flow shear on the stability of magnetic islands in tokamak plasmas**

R. Fitzpatrick and F.L. Waelbroeck

**Abstract**

The influence of local E×B flow shear on a relatively wide, constant-*ψ*, magnetic island embedded
in a large-aspect-ratio, low-*β*, circular cross-section tokamak plasma is examined, using a slab
approximation to model the magnetic geometry. It is found that there are *three* separate solution
branches characterized by low, intermediate, and high values of the shear. Flow shear is found to
have a *stabilizing* effect on island solutions lying on the low and high shear branches, via a nonlinear
modification of the ion polarization term in the Rutherford island width evolution equation, but to
have a *destabilizing* effect on solutions lying on the intermediate shear branch. Moreover, the effect
is *independent* of the sign of the shear. The modification of island stability by local E×B flow shear
is found to peak when the magnitude of the shear is approximately *v _{i} /L_{s},* where

**Comment on ‘Magnetic topology effects on Alcator C-Mod scrape-off layer flow’**

A.Y. Aydemir

**Abstract**

In their recent paper [1] Simakov et al (hereafter referred to as the authors) draw attention
to certain differences between their work and mine [2] and claim that my results contradict
an earlier work by Cohen and Ryutov [3] while theirs are in agreement, thus questioning the
validity of my work. The authors are wrong in their assertion. My work is correct and in
agreement with the relevant portions of Cohen and Ryutov’s. There are, however, serious
errors in the two primary authors’ earlier work [4] and its erratum [5] (the erratum itself is in
error) on which this paper [1] is based. *©* *2009 IOP Publishing Ltd*

DOI:10.1088/0741-3335-51-4-048001

**Generation of Fast Ions by Microclusters**

Alexey Arefiev, Boris Breizman, Vladimir Khudik, Xiaohui Gao, and Michael Downer

**Abstract**

Laser-irradiated microclusters can generate energetic ions that produce fusion reactions. The amount and spectrum of these ions depend on the cluster-size distribution, electron heating mechanism, and cluster expansion dynamics. This paper describes recent physics results pertinent to the items listed. It is shown that the size distribution of large clusters can be determined from absorption measurements in a pump-probe experiment. It is also shown how a laser can create a two-component electron distribution with a hot minority whose energies exceed the ponderomotive potential. The heating rate and the limitations on electron energy are examined. The hot electron component expands with an equal number of ions. A first-principle model is presented that describes ion acceleration by the hot electron pressure together with adiabatic cooling of the hot electrons.* © 2010 The Japan Society of Plasma Science and Nuclear Fusion Research*

**Relaxed states in relativistic multifluid plasmas**

Jesse Pino, Hui Li, and Swadesh Mahajan

**Abstract**

The evolution equations for a plasma comprising multiple species of charged fluids with relativistic bulk and thermal motion are derived. It is shown that a minimal fluid coupling model allows a natural casting of the evolution equations in terms of generalized vorticity, which treats the fluid motion and electromagnetic fields equally. Equilibria can be found using a variational principle based on minimizing the total enstrophy subject to energy and helicity constraints. A subset of these equilibria corresponds to minimum energy. The equations for these states are presented with example solutions showing the structure of the relaxed states.* © 2010 American Institute of Physics*

**Effect of dynamical friction on nonlinear energetic particle modes**

M. K. Lilley, B. N. Breizman, and S. E. Sharapov

**Abstract**

A fully nonlinear model is developed for the bump-on-tail instability including the effects of
dynamical friction (drag) and velocity space diffusion on the energetic particles driving the wave.
The results show that drag provides a destabilizing effect on the nonlinear evolution of waves.
Specifically, in the early nonlinear phase of the instability, the drag facilitates the explosive scenario
of the wave evolution, leading to the creation of phase space holes and clumps that move away from
the original eigenfrequency. Later in time, the electric field associated with a hole is found to be
enhanced by the drag, whereas for a clump it is reduced. This leads to an asymmetry of the
frequency evolution between holes and clumps. The combined effect of drag and diffusion produces
a diverse range of nonlinear behaviors including hooked frequency chirping, undulating, and steady
state regimes. An analytical model is presented, which explains the aforementioned diversity. A
continuous production of hole-clump pairs in the absence of collisions is also observed.* © 2010 American Institute of Physics*

**Parameter Optimization Studies for a Tandem Mirror Neutron**

W. Horton, X. R. Fu, A. Ivanov, and A. Beklemishev

**Abstract**

A basic plasma physics tandem mirror experiment
is proposed to develop the potential uses of magnetic
mirror confined plasmas for a neutron source. We consider
parameter variations from the currently operating symmetric
mirror plasma trap GDT in an attempt to optimize
the neutron source intensity while minimizing the expense
and complications of the system. The combined radial and
axial plasma loss rates are analyzed and shown to yield an
optimal operational point that minimizes the required
auxiliary heating power.* © Springer Science+Business Media, LLC 2010*

**Twisting Space-Time: Relativistic Origin of Seed Magnetic Field and Vorticity**

S. M. Mahajan, and Z. Toshida

**Abstract**

We demonstrate that a purely ideal mechanism, originating in the space-time distortion caused by the demands of special relativity, can break the topological constraint (leading to helicity conservation) that would forbid the emergence of a magnetic field (a generalized vorticity) in an ideal nonrelativistic dynamics. The new mechanism, arising from the interaction between the inhomogeneous flow fields and inhomogeneous entropy, is universal and can provide a finite seed even for mildly relativistic flows.

DOI:10.1103/PhysRevLett.105.095005

**The super X divertor (SXD) and a compact fusion neutron source (CFNS)**

M. Kotschenreuther, P. Valanju, S. Mahajan, L. J. Zheng, L. D. Pearlstein, R. H. Bulmer, J. Canik, and R. Maingi

**Abstract**

A new magnetic geometry, the superXdivertor (SXD), is invented to solve severe heat exhaust problems in high power
density fusion plasmas. SXD divertor plates are moved to the largest major radii inside the TF coils, increasing
the wetted area by 2–3 and the line length by 2–5. Two-dimensional fluid simulations with SOLPS (Schneider
*et al* 2006 SOLPS 2-D edge calculation code *Contrib. Plasma Phys.* 46) show a several-fold decrease in divertor
heat flux and plasma temperature at the plate. A small high power density tokamak using SXD is proposed, for
either (1) useful fusion applications using conservative physics, such as a component test facility (CTF) or fission–
fusion hybrid, or (2) to develop more advanced physics modes for a pure fusion reactor in an integrated fusion
environment.* © 2010 IAEA, Vienna, IOP Publishing Ltd.*

DOI:10.1088/0029-5515/50/3/035003

**Nonlinear travelling waves in energetic particle phase space**

B. N. Breizman

**Abstract**

An exact nonlinear solution is found for long-time behaviour of spontaneously formed phase space clumps/holes in
dissipative plasmas with a population of energetic particles. This solution represents a Bernstein–Greene–Kruskal
mode with slowly varying shape and velocity. It describes a continuous transformation of a plasma eigenmode
excited just above the instability threshold into an energetic particle mode with a significantly different frequency.
An electrostatic bump-on-tail instability is chosen to illustrate the analysis. However, generality of the resonant
particle dynamics makes the described approach applicable to other resonance-dominated instabilities, including
rapid frequency-sweeping events for Alfvénic modes in tokamaks.* © 2010 IOP Publishing Ltd.*

DOI:10.1088/0029-5515/50/8/084014

**Nonlinear magnetohydrodynamic effects on Alfvén eigenmode evolution and zonal flow generation**

Y. Todo, H. L. Berk and B. N. Beizman

**Abstract**

Nonlinear magnetohydrodynamic (MHD) effects on Alfvén eigenmode evolution were investigated via hybrid
simulations of an MHD fluid interacting with energetic particles. The investigation focused on the evolution of
an *n *= 4 toroidal Alfvén eigenmode (TAE) which is destabilized by energetic particles in a tokamak. In addition
to fully nonlinear code, a linear-MHD code was used for comparison. The only nonlinearity in that linear code
is from the energetic-particle dynamics. No significant difference was found in the results of the two codes for
low saturation levels, *δB/B ∼* 10^{−3}. In contrast, when the TAE saturation level predicted by the linear code is *δB/B ∼ *10^{−2}, the saturation amplitude in the fully nonlinear simulation was reduced by a factor of 2 due to the
generation of zonal (*n* = 0) and higher*-n* (*n* ≥ 8) modes. This reduction is attributed to the increased dissipation
arising from the nonlinearly generated modes. The fully nonlinear simulations also show that geodesic acoustic
mode is excited by the MHD nonlinearity after the TAE mode saturation.*© 2010 IOP Publishing Ltd.*

DOI:10.1088/0029-5515/50/8/084016

**Energetic-Particle-Driven Instabilities in General Toroidal Configurations**

D. A. Spong, B. N. Breizman, D. L. Brower, E. D'Azevedo, C. B. Deng, A. Konies, Y. Todo, and K. Toi

**Abstract**

Energetic-particle driven instabilities have been extensively observed in both tokamaks and stellarators. In order for such devices to ultimately succeed as D-T fusion reactors, the super-Alfvénic 3.5 Mev fusion-produced alpha particles must be sufficiently well confined. This requires the evaluation of losses from classical collisional transport processes as well as from energetic particle-driven instabilities. An important group of instabilities in this context are the discrete shear Alfvén modes, which can readily be destabilized by energetic particles (with velocities of the order of v_{Alfvén}) through wave-particle resonances. While these modes in three-dimensional systems have many similarities to those in tokamaks, the detailed implementation of modeling tools has required development of new methods. Recent efforts in this direction will be described here, with an emphasis on reduced models.* © 2010 WILEY-VCH VerlagGmbH & Co. KGaA, Weinheim*

**Relativistic Petschek reconnection with pressure anisotropy in a pair-plasma**

J. M. TenBarge, R. D. Hazeltine and S. M. Mahajan

**Abstract**

Reconnection of magnetic field lines for a wide range of parameters in the relativistic regime is considered. A newly developed covariant fluid model for magnetized plasmas, incorporating pressure anisotropy, is used to expand the study of the petschek-type reconnection in a pair-plasma governed by slow-mode shocks. The plasma parameters are found to be strongly modified by anisotropy on both sides of the shock.* © 2010 The Authors. Journal compilation ©* *2010 RAS*

DOI/10.1111/j.1365-2966.2009.16116.x

**Stable optical vortex solitons in pair plasmas**

V. I. Berezhiani, S. M. Mahajan, and N. L. Shatashvili

**Abstract**

It is shown that the pair plasmas with small temperature asymmetry can support existence of localized as
well as delocalized optical vortex solitons. Coexistence of such solitons is possible due to peculiar form of
saturating nonlinearity which has a focusing-defocusing nature—for weak amplitudes being focusing becoming
defocusing for higher amplitudes. It is shown that delocalized vortex soliton is stable in entire region of its
existence while single- and multicharged localized vortex solitons are unstable for low amplitudes and become
stable for relativistic amplitudes. *© The American Physical Society.*

DOI: 10.1103/PhysRevA.81.053812

**Application of Double Beltrami states to solar eruptions**

D. Kagan and S. M. Mahajan

**Abstract**

We show that the general class of Double Beltrami (DB) states, which are the lowest energy
equilibria of Hall magnetohydrodynamics, can have characteristics similar to those of active
regions in the solar corona and is capable of undergoing a catastrophe that can cause a solar
eruption, such as a flare or coronal mass ejection (CME). We then show that the qualitative
evolution of the DB state is consistent with that of a solar eruption. Finally, we make two
quantitative comparisons ofDBstates to CMEs,which are the simplest result of the catastrophe.
First, we show that the DB expansion by a factor of 1–2 before the catastrophe is consistent
with the increase in the height of the leading edges of Large-Angle Spectrometric Coronagraph
(LASCO C1) CMEs in the quasi-equilibrium stage. Secondly, we use the assumption that DB
states are randomly chosen from the allowed phase space of coronal structures to predict that
the probability of a coronal structure erupting is 0.046. Identifying active regions with DB
states and using observational constraints to estimate that the state is replaced every 60min
by emerging loops results in a CME rate of 11 d^{−1}, which is in reasonable agreement with the
actual rate of about 6 d^{−1} at solar maximum. *© 2010 The Authors. Journal compilation © 2010 RAS*

DOI:10.1111/j.1365-2966.2010.16741.x

**Two-fluid temperature-dependent relativistic waves in magnetized streaming pair plasmas**

A. R. Soto-Chavez, S. M. Mahajan, and R. D. Hazeltine

**Abstract**

A relativistic two-fluid temperature-dependent approach for a streaming magnetized pair plasma is considered.
Such a scenario corresponds to secondary plasmas created at the polar caps of pulsar magnetospheres. In
the model the generalized vorticity rather than the magnetic field is frozen into the fluid. For parallel propagation
four transverse modes are found. Two are electromagnetic plasma modes which at high temperature
become light waves. The remaining two are Alfvénic modes split into a fast and slow mode. The slow mode is
cyclotron two-stream unstable at large wavelengths and is always subluminous. We find that the instability
cannot be suppressed by temperature effects in the limit of large (finite) magnetic field. The fast Alfvén mode
can be superluminous only at large wavelengths, however it is always subluminous at high temperatures. In
this incompressible approximation only the ordinary mode is present for perpendicular propagation. For oblique
propagation the dispersion relation is studied for finite and large strong magnetic fields and the results are qualitatively described. *© The American Physical Society.*

DOI:10.1103/PhysRevE.81.026403

**Stable localized electromagnetic pulses in asymmetric pair plasmas**

V. I. Berezhiani, S. M. Mahajan, and N. L. Shatashvili

**Abstract**

It is shown that pair plasmas, through the new focusing-defocusing non-linearity generated by an "asymmetry" in initial temperatures of constituent species, can support multidimensional, stable, large-amplitude light bullets as well as bullets carrying vortices, *i.e.,* spinning bullets *© 2010 Cambridge University Press.*