Density and potential profiles of non-neutral electron plasmas in a magnetic mirror field

Abstract

Low-energy non-neutral electron plasmas were confined with an electrostatic potential and a magnetic mirror field of the mirror ratio up to 5. Using a conventional phosphor screen and the unique multiring trap, both radial and axial density profiles of plasmas were measured. With the present experimental parameters, it was confirmed that a plasma density increased at higher field with an electrostatic confinement and that it decreased at higher field with a magnetic mirror confinement. The electrostatic potentials along the magnetic field were estimated with computer simulations.

Electrostatic Oscillations Observed in Non-Neutral Electron Plasmas Confined in a Magnetic Field Gradient

“…And it is seen from Fig. 2 (b) that the confined plasma had a hollow profile as reported previously [2,3]. This is referred to as a magnetic mirror confinement (MMC).…”

“…In case of NNPs in a uniform magnetic field, the resonance frequency is almost proportional to n e and the oscillation phase is uniform along the field in an azimuthal direction. However, in a magnetic mirror confinement, n e changes along a magnetic field line [3]. In experiments, the signals observed with five azimuthally segmented electrodes along a curved magnetic field were almost in phase with each other.…”

Simultaneous confinement of low-energy electrons and positrons in a compact magnetic mirror trap

“…Simulations with a particle-in-cell (PIC) code Warp [34] werealso conducted to understand the initial stages of the mixing process. Warp has been used to predict and study various non-neutral plasma experiments and phenomena [35][36][37][38][39]. As a matter of course, the electrodes inside the vacuum chamber and the magnetic mirror field shown in figures 1(a) and (b) are included in the simulations.…”

Simulations on the Mixing Processes of Electrons and Positrons in a Magnetic Mirror Trap

“…For example, space potentials of non-neutral electron plasmas in a magnetic field gradient were obtained previously [22]. In case of particle simulations, it is easy to understand charged particle distributions in phase space, space potential distributions, particle trajectories, and so on, which are much more difficult to obtain in experiments.…”