The planar Multipole Resonance Probe: a functional analytic approach

TL;DR

This paper presents the first analytical model of the planar Multipole Resonance Probe (pMRP) using functional analytic methods, enabling plasma diagnostics without perturbing the plasma, and shows good agreement with previous simulations.

Contribution

It introduces a novel analytical model for the pMRP based on a cold plasma description, advancing plasma diagnostic techniques.

Findings

Explicit spectra with convergence analysis are provided.

Resonance frequencies match previous simulation results.

The model enables non-perturbative plasma diagnostics.

Abstract

Active Plasma Resonance Spectroscopy (APRS) is a well known diagnostic method, where a radio frequency probe is immersed into a plasma and excites plasma oscillations. The response of the plasma is recorded as frequency dependent spectrum, in which resonance peaks occur. By means of a mathematical model plasma parameters like the electron density or the electron temperature can be determined from the detected resonances. The majority of all APRS probes have in common, that they are immersed into the plasma and perturb the plasma due to the physical presence of the probe. To overcome this problem, the planar Multipole Resonance Probe (pMRP) was invented, which can be integrated into the chamber wall of a plasma reactor. Within this paper, the first analytic model of the pMRP is presented, which is based on a cold plasma description of the electrons. The general admittance of the probe-plasma system is derived by means of functional analytic methods and a complete orthonormal set of basis functions. Explicit spectra for an approximated admittance including a convergence study are shown. The determined resonance frequencies are in good agreement with former simulation results.