Excitation of chorus-like waves by temperature anisotropy in dipole research experiment (DREX): A numerical study

Abstract

Due to their significant roles in the radiation belts dynamics, chorus waves are widely investigated in observations, experiments, and simulations. In this paper, numerical studies for the generation of chorus-like waves in a launching device, dipole research experiment (DREX), are carried out by a hybrid code. The DREX plasma is generated by electron cyclotron resonance (ECR), which leads to an intrinsic temperature anisotropy of energetic electrons. Thus the whistler instability can be excited in the device. We then investigate the effects of three parameters, i.e., the cold plasma density n c , the hot plasma density n h , and the parallel thermal velocity of energetic electrons, on the generation of chorus-like waves under the DREX design parameters. It is obtained that a larger temperature anisotropy is needed to excite chorus-like waves with a high n c with other parameters fixed. Then we fix the plasma density and parallel thermal velocity, while varying the hot plasma density. It is found that with the increase of n h , the spectrum of the generated waves changes from no chorus elements, to that with several chorus elements, and then further to broad-band hiss-like waves. Besides, different structures of choruslike waves, such as rising-tone and/or falling-tone structures, can be generated at different parallel thermal velocities in the DREX parameter range.

Measurement of electron energetics in the equatorial and polar planes of a compact dipole plasma driven at steady state

“…These devices are, however, large in size and usually operated in pulsed wave mode, where space resolved and steady state measurements of plasma parameters were difficult. Some of their important research outcomes are confinement of high-β plasma [18], hot electron interchange instability [26,27], turbulent transport of plasma [17], the interaction of high speed neutral gas flow with dipole magnetized plasma for aerospace applications [28][29][30] and excitation of chorus-like waves owing to temperature anisotropy [31].…”

Design of HCN laser based interferometer on the Space Plasma Environment Research Facility (SPERF)

“…In the SPERF, there are two density regions for different research requirements. The low density regime is for the wave-particle interaction investigation and the high density regime is to generate the desired "Alfvén" waves [3,4]. Therefore, it is very important to provide the density information for different research.…”