Direct path from microscopic mechanics to Debye shielding, Landau damping and wave-particle interaction
The derivation of Debye shielding and Landau damping from the N-body description of plasmas is performed directly by using Newton’s second law for the N-body system. This is done in a few steps with elementary calculations using standard tools of calculus and no probabilistic setting. Unexpectedly, Debye shielding is encountered together with Landau damping. This approach is shown to be justified in the one-dimensional case when the number of particles in a Debye sphere becomes large. The theory is extended to accommodate a correct description of trapping and chaos due to Langmuir waves. On top of their well-known production of collisional transport, the repulsive deflections of electrons are shown to produce shielding, in such a way that each particle is shielded by all other ones, while keeping in uninterrupted motion.
Summary of the fundamental plasma physics session in the first AAPPS-DPP conference
Understanding of fundamental plasma physics contributes to progress in plasma science in many fields, such as magnetic confinement fusion, solar/space physics and application of plasma techniques. Intersecting common fundamental problems stimulate cross-fertilization of different topical areas. This paper summarizes the highlights of progress reported in the Fundamental Plasma Physics Session of the first conference of the Association of Asia Pacific Physical Societies-Division of plasma physics. Progress in the following fields is reviewed: (1) basic plasma theory; (2) self-organization; (3) reconnection and particle acceleration; (4) magneto-hydrodynamic instabilities and energetic particle physics; (5) magnetic confinement physics fundamentals; and (6) exploiting fundamentals for performance.
A study of the local tissue reactions in man to cortisone and compound F. VI. Histopathological studies of the local effect of compound F in normal and pathologic skin of man.
After our previous negative studies (1) of the local effect of cortisone acetate in the skin of man, a year ago, a parallel study of 17-hydroxycorticosterone-21-acetate, Compound F, was outlined. Theoretically, Compound F should be the active steroid. It was so suggested by Rothman (2), that in all probability Compound F and not cortisone would be active locally in the skin of man.