Characteristic Kα emission of electron cyclotron resonance ion source plasmas
This thesis presents the results of an investigation of the volumetric Kα emission rate/inner shell ionization rate from an Electron Cyclotron Resonance Ion Source (ECRIS) plasma tuned predominantly for high charge state ion production. The experimental work include four complimentary studies covering the inﬂuence of a parametric sweep of the four source tune parameters i.e microwave power, neutral gas ﬂow, biased disc voltage and magnetic ﬁeld on the volumetric Kα emission rate, an investigation into the gas mixing effect, an investigation into the effectiveness of double-frequency heating mode and ﬁnally an investigation into microwave induced electron losses (relative and direct) from the ECRIS plasma. The parametric sweeps revealed that only the microwave power and neutral gas ﬂow has a signiﬁcant impact on the volumetric Kα emission rate. From the study it was concluded that this observation is presumably dictated by the plasma energy content. It is also argued that this novel plasma parameter i.e. the volumetric inner shell ionization rate can be used to benchmark numerical simulations on ECRIS plasmas as this plasma parameter can easily be reproduced by most simulation codes. The investigation into the gas mixing concluded that the ion cooling effect is in all likelihood the mechanism responsible for the favourable inﬂuence of the gas mixing. One of the mechanism responsible for the favourable inﬂuence of double-frequency heating was found to be due to the increasing electron density, based on the results of the various diagnostic probes. The latter two investigations were combined with optical emission spectroscopy to directly probe the ion density of different charge states. Finally, the electron losses from an ECRIS plasma were shown to correlate with the microwave power in both CW and pulsed operations. This investigation combined a number of diagnostic methods to develop the current understanding of this scarcely studied plasma process which predominantly affects the heated electron populations of the plasma. ...
PublisherUniversity of Jyväskylä
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Influence of axial mirror ratios on the kinetic instability threshold in electron cyclotron resonance ion source plasma Toivanen, V.; Bhaskar, B. S.; Koivisto, H.; Maunoury, L.; Tarvainen, O.; Thuillier, T. (American Institute of Physics, 2022)Electron Cyclotron Resonance (ECR) ion source plasmas are prone to kinetic instabilities. The onset of the instabilities manifests as emission of microwaves, bursts of electrons expelled from the plasma volume, and the ...
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Komppula, Jani (University of Jyväskylä, 2015)
The biased disc of an electron cyclotron resonance ion source as a probe of instability-induced electron and ion losses Tarvainen, O.; Kronholm, R.; Kalvas, T.; Koivisto, H.; Izotov, I.; Skalyga, V.; Toivanen, V.; Maunoury, L. (American Institute of Physics, 2019)Electron Cyclotron Resonance Ion Source (ECRIS) plasmas are prone to kinetic instabilities resulting in loss of electron and ion confinement. It is demonstrated that the biased disk of an ECRIS can be used as a probe to ...