[en] We show that an often used relation between the radial particle flux and the divergence of the gyrotropic stress is an algebraic identity, unrelated to momentum conservation. Our calculation is completely general with regard to toroidal geometry and plasma collisionality. The result bears on the role of anisotropy in momentum relaxation and also clarifies certain methodological issues.

[en] The purpose of this Brief Communication is to emphasize the existence of a general relation between the parallel flows of heat and particles within flux surfaces and the transport of heat and particles across those flux surfaces predicted by neoclassical theory. The essential ingredients are a perspective that promotes the heat flow to the status of a fully independent dynamical variable and a unified treatment that makes no restriction regarding collisionality. Applied to well-known expressions from the literature, this approach provides a simple and explicit relation between parallel and radial flows that applies in all collisionality regimes

[en] In view of the recognized importance of electrostatic fields regarding turbulent transport, the radial electric field in a tokamak with magnetic field ripple is reconsidered. Terms in the ambipolarity condition involving the radial derivative of the field are derived from an extended drift-kinetic equation, including effects of second order in the gyroradius. Such terms are of interest in part because of their known importance in rotational relaxation equations for the axisymmetric case. The electric field is found to satisfy a nonlinear differential equation that is universal in a certain sense, and that implies spatial relaxation of the potential to its conventionally predicted value.

[en] It is pointed out that the viscosity coefficient describing radial transport of toroidal angular momentum is proportional to the second power of the gyro-radius—like the corresponding coefficients for particle and heat transport—regardless of any geometrical symmetry. The observation is widely appreciated, but worth emphasizing because some literature gives the misleading impression that asymmetry can allow radial moment transport in first-order

No abstract available

[en] Thermal fluctuations in a magnetized, anisotropic plasma are studied by applying standard methods, based on the Einstein rule, to the known thermodynamic potential of the system. It is found in particular that magnetic fluctuations become critical when the anisotropy p_∥−p_⊥ changes sign. By examining the critical region, additional insight on the equations of state for near-critical anisotropic plasma is obtained

[en] 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.

[en] An isothermal truncation of the electromagnetic gyrofluid model of Snyder and Hammett [Phys. Plasmas 8, 3199 (2001)] is shown to be Hamiltonian. The corresponding noncanonical Lie-Poisson bracket and its Casimir invariants are presented. The invariants are used to obtain a set of coupled Grad-Shafranov equations describing equilibria and propagating coherent structures.

[en] Noise theory is used to study the temporal correlations of stationary random fluctuations that are homogeneous in space. Statistical properties of the fluctuations, such as the power spectrum and the correlation function, are computed. The results are compared with the observed plasma density fluctuations from tokamak experiments

[en] Many astrophysical plasmas and some laboratory plasmas are relativistic: Either the thermal speed or the local bulk flow in some frame approaches the speed of light. Often, such plasmas are magnetized in the sense that the Larmor radius is smaller than any gradient scale length of interest. Conventionally, relativistic magnetohydrodynamics (MHD) is employed to treat relativistic, magnetized plasmas. However, MHD requires the collision time to be shorter than any other time scale in the system. Thus, MHD employs the thermodynamic equilibrium form of the stress tensor, neglecting pressure anisotropy and heat flow parallel to the magnetic field. Recent work has attempted to remedy these shortcomings. This paper re-examines the closure question and finds a more complete theory, which yields a more physical and self-consistent closure. Beginning with exact moments of the kinetic equation, we derive a closed set of Lorentz-covariant fluid equations for a magnetized plasma allowing for pressure and heat flow anisotropy. Basic predictions of the model, especially of the dispersion relation's dependence upon relativistic temperature, are examined