Investigation of collective properties in hydrogen pair-ion plasma and verification of ion binary system

2020 Fiscal Year Final Research Report

• Project/Area Number: 18H01195
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 14010:Fundamental plasma-related
• Research Institution: Yamaguchi University
• Principal Investigator: Oohara Wataru 山口大学, 大学院創成科学研究科, 教授 (80312601)
• Co-Investigator(Kenkyū-buntansha): 吉田 雅史 山口大学, 大学院創成科学研究科, 助教 (80638825)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: プラズマ・核融合 / ペアイオンプラズマ / 水素負イオン

Outline of Final Research Achievements

In order to realize a hydrogen ionic plasma consisting of positive and negative ions without negative-ion collapse, the voltage conditions of positive-ion acceleration voltage and ion control-grid voltage that can suppress negative-ion collapse have been clarified. Although the existence of the rotating pair structure of atomic hydrogen positive and negative ions, which was hypothesized as the cause of negative-ion collapse, could not be clearly shown, the next candidate substance, aluminum hydride negative ions, was found. By exciting and propagating electrostatic waves, the details of the dispersion relation of 1 MHz or less were clarified. It became clear that there are traveling waves (phase velocity is positive), reverse waves (phase velocity is negative), and backward waves (group velocity is negative), and the frequency band and attenuation rate of these modes depend on the positive ion energy.

Free Research Field

プラズマ理工学

Academic Significance and Societal Importance of the Research Achievements

ペアプラズマは粒子運動に関連した時空間対称性を有する独特の媒体なので，その物性解明が世界的に注目されてきた．ペアプラズマに類似する水素イオン性プラズマが実現され，従来に比べて1桁以上高周波数まで，伝搬波の分散関係が明らかになったことは大きな進歩である．また，通常の伝搬波である進行波だけでなく，物理的に理解し難い逆進行波の存在が明らかになったことは，集団物性の解明という基礎研究に新たな知見もたらしたと言える．