Effects of E × B drift on electron transport across the magnetic field in a miniature microwave discharge neutralizer

Abstract

Using a three-dimensional particle-in-cell model, electron transport across a magnetic field has been investigated by obtaining the time-varying electric field and plasma parameters in a miniature microwave discharge neutralizer. The size of the neutralizer is 20 × 20 × 4 mm 3. Inside is a ring-shaped antenna producing 4.2 GHz microwaves, and permanent magnets for xenon plasma discharges. There are four orifices for electron extraction. The simulation area consists of both the discharge chamber and the vacuum region for the extraction. The numerical results show that radial striped patterns occur where the peak electron density is obtained, and the patterns seem to rotate in the azimuthal direction. This characteristic

Numerical Analysis of a Miniature Microwave-discharge Ion Thruster Using Water as the Propellant

“…These stripped patterns and the time-averaged vectors of the electric field, such as those shown in Fig. 7(b), were also confirmed in a previous study, 19) and similar electron extraction can be expected in view of the plasma structure, where the azimuthal electric field and the radial magnetic field lead to electron transport across the magnetic field.…”

Effects of negative ions on discharge characteristics of water plasma source for a miniature microwave discharge ion thruster

“…The distributions exhibited characteristic striped patterns rotating clockwise with time; a similar physical phenomenon was observed and investigated in the xenon plasma source in the previous work. 34 Moreover, the clockwise rotation showed the dependence on the grad-B and…”

“…An E Â B drift velocity in the positive z-direction was found to play an important role in the cross-B field transport in a miniature ECR xenon plasma source. 34 Such a velocity is composed of the azimuthal electric field induced by the plasma potential fluctuation and the radial magnetic field of the permanent magnets. Meanwhile, the neutralizer in the water ion thruster employs the same plasma source as the ion source.…”

Electron extraction enhancement via the magnetic field in a miniature microwave discharge neutralizer

“…The 3D PIC-MCC simulations were based on our previous papers. 8,[22][23][24] In the simulations, we employed the following assumptions: (i) only singly charged xenon ions and electrons are treated as particles;…”

“…Using a 3D particle model in a previous study, we found that the fluctuations in the azimuthal electric field and the mirror magnetic confinement in the radial direction caused an E × B drift velocity in the positive z-direction, contributing to the electron transport across the magnetic field inside the discharge chamber. 8 This type of result cannot be obtained using two-dimensional models, which have often been employed to model other E × B devices, such as Hall thrusters 9-14 and magnetron discharges. 15,16 In addition, we numerically investigated the electron extraction mechanisms through the orifices of the neutralizers, which is also difficult to measure experimentally, and found that the E × B drift caused electron extraction mainly on one side of each orifice 17 and that electrons were also extracted along magnetic field lines.…”