Coupling between multiple antennas through a plasma cylinder

TL;DR

This paper investigates how a plasma cylinder enhances electromagnetic coupling between multiple antennas, combining experimental measurements with theoretical analysis to inform plasma source and thruster design.

Contribution

It provides detailed experimental data and theoretical insights into antenna coupling through plasma, a novel investigation relevant for plasma-based propulsion systems.

Findings

Plasma column significantly increases antenna coupling.

Experimental mutual induction currents are quantitatively measured.

Theoretical models confirm the coupling mechanism.

Abstract

The coupling physics between multiple antennas separated axially along a plasma cylinder is investigated. Experiments are carried out on a recently built device: Physics ANd Thruster oriented HElicon Research (PANTHER), with an upgrade of second-stage antennas. Mutual induction currents are measured in detail. It is found that the existence of plasma column going through these antennas increase the coupling effects among them significantly. Theoretical analyses from the perspectives of transformer and magnetic permeability and moment confirm the reasonability of this phenomenon. This work is of particular interest for electrodeless plasma source or thruster which employs multiple antennas for ionisation and acceleration.