Upper hybrid resonance heating experiments by X-mode microwaves on electron cyclotron resonance ion source

Yushi Kato; Takuya Nishiokada; Kouta Hamada; Koji Onishi; Tatsuto Takeda; Kazuki Okumura; Takayuki Omori; Wataru Kubo; Masaki Ishihara; Shuhei Harisaki

doi:10.1063/1.5127315

Upper hybrid resonance heating experiments by X-mode microwaves on electron cyclotron resonance ion source

Rev Sci Instrum. 2020 Jan 1;91(1):013315. doi: 10.1063/1.5127315.

Authors

Affiliation

¹ Division of Electrical, Electronic and Information Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita-shi, Osaka 565-0871, Japan.

PMID: 32012523
DOI: 10.1063/1.5127315

Abstract

We have considered the accessibility condition of electromagnetic and electrostatic waves propagating in an electron cyclotron resonance (ECR) ion source (ECRIS) plasma and then investigated experimentally their correspondence relationships with production of multicharged ions. It has been clarified that there exists an efficient configuration of ECR zones for producing multicharged ion beams and has been suggested that a new resonance, i.e., upper hybrid resonance (UHR), must have occurred. We have been trying to perform advanced experiments with 4-6 GHz X-mode microwaves to the 2.45 GHz ECRIS plasma, and we have succeeded in enhancing the production of multicharged ions by launching X-mode microwaves of these bands. Furthermore, at the same time, we have observed sharp increases in electron energy distribution functions in the ECRIS plasma by means of probe methods. It has been concluded that the UHRs must have occurred when applying multiplex microwaves with their frequencies away from those frequencies for ECR in the ECRIS. In this paper, we will describe in brief the theoretical background and the results of these new experiments.