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Abstract

THE CLASSICAL PHENOMENON OF ELECTRON PLASMA OSCILLATIONS WAS INVESTIGATED. THE APPLICABILITY OF STANDARD NORMAL MODE ANALYSIS OF PLASMA PERTURBATIONS WAS JUDGED FROM COMPARISONS WITH EXACT, NUMERICAL CALCULATIONS FOR BOTH MAXWELLIAN AND NON-MAXWELLIAN VELOCITY DISTRIBUTIONS. THE CORRESPONDING LARGE DEBYE DISTANCE (LDD) DAMPING WAS FOUND TO DOMINATE OVER LANDAU DAMPING. THE PHYSICS OF LDD DAMPING AND ITS CLOSE CONNECTION TO LARGE LARMOR RADIUS (LLR) DAMPING IS DISCUSSED. A MAJOR FINDING CONCERNED PERTURBATIONS OF PLASMAS WITH NON-MAXWELLIAN, BUMP-IN-TAIL, VELOCITY DISTRIBUTION FUNCTIONS F(W), WHERE THE PLASMA RESPONDED BY DAMPING PERTURBATIONS WHICH WERE INITIALLY UNSTABLE IN THE LANDAU SENSE, IE WITH PHASE VELOCITIES INITIALLY IN THE INTERVAL WHERE F(W)>=0. IT WAS FOUND THAT THE PLASMA RESPONDS THROUGH SHIFTING THE PHASE VELOCITY ABOVE THE UPPER VELOCITY LIMIT OF THIS INTERVAL. THIS WAS SHOWN TO BE DUE TO A RESONANCE WITH THE DRIFTING ELECTRONS OF THE BUMP, AND EXPLAINS THE PENROSE CRITERION.

Additional information

Authors: SCHEFFEL J, ROYAL INSTITUTE OF TECHNOLOGY, STOCKHOLM, SWEDEN;LEHNERT B ROYAL INSTITUTE OF TECHNOLOGY, STOCKHOLM, SWEDEN, ROYAL INSTITUTE OF TECHNOLOGY, STOCKHOLM, SWEDEN
Bibliographic Reference: REPORT TRITA-PFU-88-06, 1988, AVAILABILITY: ROYAL INSTITUTE OF TECHNOLOGY, STOCKHOLM
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