Plasma Dynamics in a High-Power Helicon Source
type: CreativeWork
description: The magnetically confined plasma in the ITER fusion reactor must reach temperatures over 100 million kelvin to sustain fusion reactions. Neutral Beam Injectors (NBIs) will provide most of the heating power by accelerating negative ions to energies of 1 MeV, where they are then neutralised to penetrate the magnetic confinement fields. Negative ions, as opposed to positive ions, are required due to their higher neutralisation efficiency at these energies but are much more challenging to produce in sufficient quantities. Present designs for generating negative ions use Inductively Coupled Plasmas (ICPs) at high powers up to 100 kW. Previous studies have shown that Helicon Coupled Plasmas (HCPs) can generate higher plasma densities at lower powers, and hence, could be used to improve the efficiency of these systems. However, limited studies have been performed that compare ICPs and HCPs at powers greater than 3 kW for pressures less than 10 mTorr with a focus on negative ion production. In this research, we use the MAGnetised Plasma Interaction Experiment (MAGPIE) device to investigate and compare several plasma parameters for these two methods of RF coupling for powers up to 20 kW at a pressure between 3 mTorr and 7 mTorr in hydrogen. Electron dynamics have been measured using an RF-compensated Langmuir probe axially along the chamber operated with and without an expanding magnetic field. Several non-invasive spectroscopic techniques have been implemented such as Tuneable Diode Laser Absorption Spectroscopy (TDLAS) to determine atomic temperatures, Cavity Ring-Down Spectroscopy (CRDS) for direct negative ion density measurements, and an absolute intensity calibrated Optical Emission Spectroscopy (OES) method in conjunction with the YACORA Collisional Radiative Model and an extended global model. OES is used to determine molecular translational, vibrational and rotational temperatures while considering surface recombination effects. It is also used to obtain the electro…
abstract: The magnetically confined plasma in the ITER fusion reactor must reach temperatures over 100 million kelvin to sustain fusion reactions. Neutral Beam Injectors (NBIs) will provide most of the heating power by accelerating negative ions to energies of 1 MeV, where they are then neutralised to penetrate the magnetic confinement fields. Negative ions, as opposed to positive ions, are required due to their higher neutralisation efficiency at these energies but are much more challenging to produce in sufficient quantities. Present designs for generating negative ions use Inductively Coupled Plasmas (ICPs) at high powers up to 100 kW. Previous studies have shown that Helicon Coupled Plasmas (HCPs) can generate higher plasma densities at lower powers, and hence, could be used to improve the efficiency of these systems. However, limited studies have been performed that compare ICPs and HCPs at powers greater than 3 kW for pressures less than 10 mTorr with a focus on negative ion production. In this research, we use the MAGnetised Plasma Interaction Experiment (MAGPIE) device to investigate and compare several plasma parameters for these two methods of RF coupling for powers up to 20 kW at a pressure between 3 mTorr and 7 mTorr in hydrogen. Electron dynamics have been measured using an RF-compensated Langmuir probe axially along the chamber operated with and without an expanding magnetic field. Several non-invasive spectroscopic techniques have been implemented such as Tuneable Diode Laser Absorption Spectroscopy (TDLAS) to determine atomic temperatures, Cavity Ring-Down Spectroscopy (CRDS) for direct negative ion density measurements, and an absolute intensity calibrated Optical Emission Spectroscopy (OES) method in conjunction with the YACORA Collisional Radiative Model and an extended global model. OES is used to determine molecular translational, vibrational and rotational temperatures while considering surface recombination effects. It is also used to obtain the electro…
author: Strachan, Campbell
language: en_AU
date published: 2024
date modified: 2026-07-24T00:54:30Z
provider: Australian National University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Australian National University

PropertyValue
property ID: Handle
value: http://hdl.handle.net/1885/311823