Magnetic Confinement of Cryogenic Plasma Produced by Pulsed Discharges in Superfluid Liquid Helium

超流液氦中脉冲放电产生低温等离子体的磁约束

• 批准号: 12680475
• 负责人: MINAMI Kazuo
• 金额: $ 1.98万
• 依托单位: Niigata University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12680475/
• 关键词: Liquid Helium; Superconducting Coil; Pulsed Discharge; Stark Broadening; Magnetic Confinement; Mirror Field; Cusp Field; Needle Electrodes; 超伝導マグネット; 超流動; 極低温; プラズマ; 磁場閉じ込め; ミラー磁界; カスプ磁界; 磁気圧

The effect of magnetic confinement has been investigated on the density decay of afterglow plasma produced by pulsed discharges between needle electrodes embedded in a split type superconducting coils with maximum magnetic field 2 T immersed in superfluid liquid helium (LHe). A pair of needle tungsten electrodes in mirror- or cusp-types magnetic field in LHe are fired by high voltage pulses of 20 kV, current 50 A, and time width 1.0μs. The Stark broadening of spectral line 587.6 nm from neutral helium atoms in plasma is observed to measure local plasma density. At time t=0.5μs after the discharge, the plasma density n=10^<18>cm^<-3>, and electron temperature Te=32,000 K. For a period until t=3.0μs after the dischagges, the estimated beta value defined by the ratio of plasma and magnetic pressures changes from 0.28 to 0.014. Effects of applied magnetic field are assumed to be evident. Somewhat surprisingly, no changes in density decays with and without magnetic field can be detected until t=3.0μs for both mirror- and cusp-type cases. We observe total light intensity until t=18 ms for detecting the difference. No differences with and without the magnetic field are detected. Reducing the pressure and temperature of LHe results in no difference.

磁性限制的作用已被刺激在脉冲放电中产生的余辉等离子体的密度，这些杆嵌入了分裂型的超导卷管中，并具有最大的磁场2在超级流体液体氦气中的时间（LHE）中。通过20 kV的高电压脉冲，目前50 a，观察到血浆中中性氦原子的ctral线587.6 nm在排放后的时间t =0.5μs。 ^<18> cm^<-3> til t =3.0μs，截止后，估计的beta值由等离子体和磁性的比例从0.28到0.014 ，对于两种镜子和尖锐的情况，我们的密度没有变化。

项目成果

K. Minami, Y. Yamanishi, C. Kojima, M. Shindo and O. Ishihara: "Very Slowly Decaying Afterglow Plasma in Cryogenic Helium Gas"IEEE Transactions Plasma Sciene. vol.31,no.3(in printing). (2003)

K. Minami、Y. Yamanishi、C. Kojima、M. Shindo 和 O. Ishihara：“低温氦气中缓慢衰变的余辉等离子体”IEEE Transactions Plasma Sciene。

E.Minami, Y.Yamanishi, C.Kojima, M.Shindo, O.Ishihara: "Very Slowly Decaying Afterglow Plasma in Cryogenic Helium Gas"IEEE Transactions Plasma Science. 31(印刷中). (2003)

E. Minami、Y. Yamanishi、C. Kojima、M. Shindo、O. Ishihara：“低温氦气中缓慢衰变的余辉等离子体”IEEE Transactions Plasma Science 31（出版中）。