Electrostatic Ion Cyclotron and Ion Plasma Waves in a Symmetric Pair-Ion Plasma Cylinder

Abstract

Complicated wave behavior observed in the cylindrical pair-ion (fullerene) experiments by Oohara and co-workers are now identified to be low harmonic ion cyclotron waves combined with ion plasma oscillations inherent to kinetic theory. The electrostatic dispersion equation derived is based on an approximation for the current from the exact solutions of the characteristic cylindrical geometry form of the Vlasov plasma equation in a uniform magnetized plasma cylinder surrounded by a larger metal boundary outside a vacuum gap, which thus differs from that in unbounded plasmas. Positive and negative ions, differing only in the sign of their charge, respond to a potential in the same time scale and cooperate to reflect the enhanced kinetic orbital behaviors to the macroscopic propagation characteristics. In addition, the experimental value of the Larmor radius (comparable to the discharge radius but small enough to make the analytic approximation useful) makes higher harmonic ion cyclotron effects both observable and calculable with the appropriate approximation for the kinetic theory.

Debye length and plasma skin depth: two length scales of interest in the creation and diagnosis of laboratory pair plasmas

“…Electrostatic modes investigated. Gyroradius ≈ plasma radius (Oohara & Hatakeyama 2003;Oohara, Date & Hatakeyama 2005;Kono, Vranjes & Batool 2014).…”

New longitudinal mode and compression of pair ions in plasma

“…Pair (pi) plasmas consisting of only positive and negative ions, produced in laboratory, have received considerate [1][2][3][4][5][6][7][8][9][10][11] attention for the reason that such plasmas have allowed the investigation of many classic problems of physics by opening a door for the scientists curious to understand the phenomena occurring hundred of light years away in the astrophysical environment, this motivates us to address this an advancement in the "laboratory astrophysics".…”

“…A basic requirement for long time scale experiments will be that the pair annihilation time scale is many orders of magnitude larger than the plasma period. However, the disagreement between experimental observations and basic fluid theory is yet to be resolved and has divided the concerned scientific community [4][5][6][7].…”

“…In Japan, Hatekayama and Oohara [24,25] succeeded in creating lighter pair plasma with hydrogen; however, efforts are being made to accomplish its improved quality. In parallel, for the theoreticians it's a challenge to explain some of the results and some attempts have been made with kinetic theory taking into account the boundary effects [7].…”

Gyro-viscosity and linear dispersion relations in pair-ion magnetized plasmas

“…The pioneering experimental studies on propagation properties of electrostatic waves in pair-ion plasmas 1−5 have been explained by a kinetic theory 6,7 , which shows the importance of the finite Larmor radius effects and suggests that a fluid theory can reproduce the experimental results so long as the fundamental waves are concerned if the finite Larmor radius effects are properly taken into account. The main point of the experiment is backward waves which had been left unexplained after a number of theoretical works 8−14 .…”