摘要:

The fields excited by a short dipole antenna in a hot uniaxially anisotropic plasma(B0→∞)have been studied. When&ohgr;<&ohgr;p, the dipole effectively excites two propagating waves, a slow wave and a fast wave, inside a cone of half‐cone anglesin−1(&ohgr;/&ohgr;p). Inside the cone a characteristic interference structure in the angular distribution of the fields is noted. Outside the cone fields fall off exponentially. The appearance of the cone and the characteristic interference structure in the field is useful from the viewpoint of laboratory diagnostics.

ISSN:0031-9171    

DOI:10.1063/1.1694176

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Under certain conditions of electron temperature and mean free path the attenuation of an electromagnetic wave incident on a vacuum‐plasma boundary cannot be described in terms of the usual complex conductivity. In a cylindrical plasma with an electron density lying between 1010and 1012cm−3, and an electron temperature of 2.2 eV measurements of the attenuation of a small amplitude wave show resonance phenomena due to interaction between the wave and the moving electrons. A theory of this resonance for the case of a plasma slab is compared to the experimental results.

ISSN:0031-9171    

DOI:10.1063/1.1694177

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Equations are derived for near‐equilibrium transport of plasma in a strong magnetic field. These equations reduce to the collision dominated (fluid) equations, and to the collisionless (Chew‐Goldberger‐Low) equations in the respective limits.

ISSN:0031-9171    

DOI:10.1063/1.1694179

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The variational technique for calculating all the neoclassical transport processes in the banana regime, developed by Rosenbluth, Hazeltine, and Hinton for the case of tokamak with small rotational transform and large aspect ratio, is generalized to arbitrary axisymmetric toroidal systems with a small fraction of trapped particles. The use of the scalar magnetic potential as a coordinate, as in Rutherford's treatment of the Lorentz model, is eliminated by the use of a coordinate‐free solution procedure, allowing the treatment of nonvacuum fields. As an example, results are given for doublet II.

ISSN:0031-9171    

DOI:10.1063/1.1694180

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Statistical mechanics is developed for a two‐dimensional guiding center plasma. Because there is no kinetic energy associated with guiding center motion, this development is unconventional. Thermal equilibrium is discussed, and an interesting limiting case is noted. Using the random phase assumption, a kinetic equation for the density fluctuations is obtained, which has thermal equilibrium and its limiting form as the only stationary states. However, despite the phase averaging this kinetic equation is reversible and when disturbed the system oscillates about equilibrium. Similar oscillatory behavior appears in the microscopic correlation function of the fluctuations, and the oscillation frequencies are obtained explicitly; however, these oscillations do not significantly change the macroscopic diffusion coefficient derived earlier by McNamara and Taylor.

ISSN:0031-9171    

DOI:10.1063/1.1694155

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The error incurred through the customary neglect of the velocity dependence of the Coulomb logarithm was evaluated by reexamining the problem of the deceleration of a test particle in a plasma. Numerical results indicate that a neglect of this velocity dependence results in an underestimation of the energy deposited by a test particle in the ion field of a plasma.

ISSN:0031-9171    

DOI:10.1063/1.1694156

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A statistical method for describing the collisionless (in general non‐Maxwellian) equilibria and the stability of inhomogeneous Vlasov plasmas is proposed and applied to various electrostatic cases. By means of this method the entropy and the other thermodynamic potentials can be calculated. The entropy principle allows the calculation of the electrostatic equilibria which are preferably chosen by the plasma. It is shown that the Bernstein‐Greene‐Kruskal sinusoidal wave is a maximum of the entropy provided dissipative processes are neglected. Examples are given of the general property of a collisionless system to evolve toward the marginal stability point. In one example the evolution of a bump‐in‐tail distribution toward a plateau is easily shown. It also follows from the theory that the collisionless dissipative processes always imply the excitation of short wavelength modes.

ISSN:0031-9171    

DOI:10.1063/1.1694157

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A general mechanism of large‐amplitude stabilization of the drift instability is investigated. For slab geometry, a drift‐wave potential of the form&phgr; = &PHgr; cos(kxx) cos(kyy+kzz−&ohgr;t)is used wherexis the direction of plasma density inhomogeneity andzis the direction of a uniform field. It is assumed thatkx∼ky≫kzand&ugr;i≪&ohgr;/kz≪&ugr;e. Studies of the exact guiding‐center particle trajectories in the drift‐wave potential show the existence of time‐average,y‐direction velocities whose magnitudes increase with the amplitude of the drift wave. As the wave grows, these velocities shift parts of the resonance region away from&ugr;z = &ohgr;/kzand finally into the bulk of the ion distribution. Thus, the original instability is stabilized by strong ion Landau damping. Stabilization will occur around the wave amplitude satisfying the condition,ckx&PHgr;/B=&ohgr;/ky.

ISSN:0031-9171    

DOI:10.1063/1.1694159

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Axially symmetric toroidal plasma equilibria with spherical or near‐spherical plasma‐vacuum boundaries are examined when variations in the distribution function produce anisotropic pressures. A separable analytic solution is found when the pressure deviation from isotropy is small; the degree of anisotropy is used as an expansion parameter in the perturbation scheme. In general, the plasma‐vacuum boundaries deform slightly and spherical boundaries cannot be maintained by externally applied fields that remain finite at large distances. Whenp⊥>p‖, the plasma becomes a prolate spheroid and whenp‖<p⊥it becomes oblate.

ISSN:0031-9171    

DOI:10.1063/1.1694160

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The relaxation of anisotropic collisionless plasma distributions due to whistler mode instabilities is calculated through quasilinear theory, for various values of background magnetic field strength. The results are compared with previous computer simulation experiments and with the predictions of classical (collision dominated) transport theory.

ISSN:0031-9171    

DOI:10.1063/1.1694161

出版商:AIP    

年代:1973

数据来源: AIP