Experiments on Echoes in Nonneutral Plasmas

Research Project

Project/Area Number	09680463
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	プラズマ理工学
Research Institution	KYOTO UNIVERSITY
Principal Investigator	TANAKA Hitoshi Kyoto Univ., Energy Science, Associate Professor, エネルギー科学研究科, 助教授 (90183863)
Co-Investigator(Kenkyū-buntansha)	MOHRI Akihiro Kyoto Univ., Integrated Human Studies, Professor, 名誉教授 (10025926) ASAKAWA Makoto Kyoto Univ., Science, Assistant, 理学研究科, 助手 (30280704) TERUMICHI Yasushi Kyoto Univ., Science, Professor, 理学研究科, 教授 (50025384) MAEKAWA Takashi Kyoto Univ., Energy Science, Professor, エネルギー科学研究科, 教授 (20127137)
Project Period (FY)	1997 – 1998
Project Status	Completed (Fiscal Year 1998)
Budget Amount *help	¥2,800,000 (Direct Cost: ¥2,800,000) Fiscal Year 1998: ¥1,100,000 (Direct Cost: ¥1,100,000) Fiscal Year 1997: ¥1,700,000 (Direct Cost: ¥1,700,000)
Keywords	Non-neutral plasma / Echoes / Nonlinear Waves / Electrostatic Mode Waves
Research Abstract	Using with a Multi-Ring Electrodes Trap, the "quiet" pure electron plasmas necessary for the echo experiments are produced, and applying electrostatic wave packets to this plasma, below results are obtained. (1) The Quadrapole electrostatic potential field for trapping is produced by applying the voltage to the 41 ring electrodes as V(z_j) = V_<well>z_j^2/L^2, and the spheroidal pure electron plasmas are formed. The Field Emitter Array cathode is used for the electron source. The electron density is controlled by multi-pulse stacking method. The electron temperature is changed by heating with axisymmetric electrostatic mode (1 = 1, 2, ...). At the magnetic field strength of 400 G, pure electron plasmas with the length 40 - 50 cm, the density 10^6 - 10^7 cm^3, the temperature 0.2 - 8 eV are confined very "quietly". (2) Two burst wave packets are applied to the end electrode with some time interval and the electrostatic perturbations are observed at different electrodes using with broad band and high gain amplifies. They are recorded by the 4 ch high speed digital storage scope and the frequency spectra are obtained. The results show that after the second wave packets are damped away new electrostatic waves are excited, i.e. echo phenomena. There occur exclusive transitions from one mode to one other and the phenomena include complicated processes. The newly excited mode is identified to the Trivelpiece-Gould mode in the pure electron plasmas.