Experinuital Study of Large-Scale Emu Release by Transient and Intermittent Magnetic Reconnection

瞬态间歇磁重联大规模释放鸸鹋的实验研究

• 批准号: 14380208
• 负责人: ONO Yasushi
• 金额: $ 10.82万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14380208/
• 关键词: Magnetic Reconnection; Transient Reconnection; Plasmoid; Current-Sheet Ejection; Anomalous Resistivity; Solar Corona; Numerical Simulation; Magnetosphere Plasmas

The large-scale energy release of transient and intermittent magnetic reconnection has been studied in the TS-3/4 device using two merging plasma toroids with arbitrary colliding speeds. Two plasma toroids with major radii R^-0.2m (TS-3) were collided and merged together in the axial direction by the help of compression force provided by external acceleration coils. The magnetic reconnection transformed the magnetic energy of reconnecting magnetic field first through the outflow energy finally to the thermal energy, increasing the plasma beta up to 30-50%, A new finding is that the transient effect of magnetic reconnection causes the fast merging speed as well as the high-power heating, even if effective resistivity of the current sheet is as low as classical. Their heating energy increases significantly with their reconnection speed, because the heating is cased by the reconnection outflow. The plasma colliding (inflow) speed was varied from zero to 30% of the Alfven speed V_A using c … More ompression coil/ PF coil currents. When the inflow speed was slower than 0.05 V_A, the plasma inflow flux balanced with the outflow flux, indicating the quasi-steady reconnection (dB/dt^- dn/dt^-0) like the MRX experiment. When the inflow speed exceeded 0.1-0.2V_A, the inflow flux exceeded the outflow flux in the early reconnection phase, causing clear pileup of plasma and magnetic flux in the current sheet. When the inflow speed was increased over 0.2V_A, two types of fast reconnection mechanisms were observed to appear in the late reconnection phase. When the gyro-radius p_i was relatively large, the fast inflow compressed the sheet width δ shorter than p_i, causing the anomalous increase in the effective current sheet resistivity and the reconnection speed. A question is how the inflow speed increases if the fast inflow over-compresses the current sheet whose effective resistivity η is as low as the classical one η_<cl>. When the condition : δ>>p_i maintained η^-η_<cl>, the inflow flux was observed to pileup around the current sheet, causing the rapid growth and peaking of the current sheet. When the flux pileup exceeded the critical limit, the sheet was ejected mechanically from the squeezed X-point area. The reconnection speed was relatively slow during the flux-pileup and became drastically fast during the ejection, in agreement with the solar corona observations. The sheet ejection was found to occur twice or three times. if we increases the initial reconnecting flux sufficiently large. These facts indicate that the plasma inflow fluxes larger than the plasma outflow fluxes transformed the quasi-steady reconnection though the transient one, finally to the intermittent one under the low resistivity condition (p_i<<δ). It is concluded that the growth and ejection of current sheet both increase plasma inflow (reconnection speed) due to its mass accumulation and ejection, respectively. Based on these results, the transient shaping effect of current sheet is concluded to makes the reconnection (and outflow) faster, even if the sheet resistivity stays as low as the classical one. Less

在TS-3/4装置中，利用任意碰撞速度的两个合并等离子体环面，研究了瞬态和间歇磁重联的大规模能量释放。在外部加速线圈提供的压缩力的帮助下，两个主要半径为R^-0.2m （TS-3）的等离子体环面在轴向上发生碰撞并合并在一起。磁重联首先将重联磁场的磁能通过流出能最终转化为热能，使等离子体β提高了30-50%。新的发现是，即使电流片的有效电阻率与经典一样低，磁重联的瞬态效应也会导致快速的合并速度和高功率加热。它们的加热能量随着重联速度的增加而显著增加，因为加热是由重联出口引起的。使用c…More压缩线圈/ PF线圈电流，等离子体碰撞（流入）速度从0到Alfven速度V_A的30%变化。当流入速度低于0.05 V_A时，等离子体流入通量与流出通量平衡，表明与MRX实验类似的准稳定重联（dB/dt^- dn/dt^-0）。当流入速度超过0.1 ~ 0.2 v_a时，在重联初期流入通量超过流出通量，导致电流片内等离子体和磁通量明显堆积。当注入速度增加到0.2V_A以上时，在重连后期出现了两种快速重连机制。当陀螺半径p_i较大时，快速流入压缩片宽δ小于p_i，导致有效电流、片电阻率和重联速度异常增大。一个问题是，如果快速流入过度压缩有效电阻率η与经典的η_<cl>一样低的电流片，流入速度如何增加？当δ>>p_i保持η^-η_<cl>时，流入通量在流片周围堆积，导致流片快速增长并达到峰值。当熔剂堆积超过临界极限时，板材被机械地从挤压的x点区域弹出。在通量堆积期间，重联速度相对较慢，在抛射期间，重联速度急剧加快，这与太阳日冕观测结果一致。发现钢板抛射发生了两次或三次。如果我们将初始重接通量增大到足够大。说明在低电阻率条件下（p_i<<δ），等离子体流入通量大于等离子体流出通量使准稳态重联由瞬态重联转变为间歇重联。结果表明，电流片的生长和喷出分别由于其质量积累和喷出而增加了等离子体流入（重联速度）。基于这些结果，得出了电流片的瞬态整形效应，即使电流片的电阻率保持与经典电阻率一样低，也会使重联（和流出）更快。少

项目成果

Heating Properties of Merging/ Reconnection Startup of High-Beta ST

High-Beta ST 合并/重连启动的加热特性

• 发表时间: 2005
• 期刊: IEEJ Transactions on Fundamentals and Materials 125-A (11)
• 作者: Y. Ono;M. Inomoto
• 通讯作者: M. Inomoto

Numerical Simulation and Experiment of Magnetic Reconnection Outflow under Neutral Particles

中性粒子下磁重联流出的数值模拟与实验

• 发表时间: 2004
• 期刊: IEEJ Transactions on Fundamentals and Materials Vol.124-A, No.2
• 作者: Y.Murata;Y.Ono
• 通讯作者: Y.Ono

Chapter 5 : Laboratory Experiments of Magnetic Reconnection (Physics of Magnetic Reconnection in High Temperature Plasmas)

第5章：磁重联实验室实验（高温等离子体磁重联物理）

• 发表时间: 2004
• 期刊: Research Signpost Co.
• 作者: N.Arita;S.Sakurai;H.Kurisu;S.Yamamoto;M.Matsuura;S.Fukada;Y.Ono
• 通讯作者: Y.Ono

Radial Velocity Profile Reconstruction by Ion Doppler Spectroscopy Measurements

通过离子多普勒光谱测量重建径向速度分布

• 发表时间: 2003
• 期刊: European Physical Journal D 125-A
• 作者: A.L.Balandin;Y.Ono;Y.Murata
• 通讯作者: Y.Murata

球状卜カマク立ち上げ時の巨視的不安定

发射球形卡马克时的宏观不稳定性

• 发表时间: 2005
• 期刊: 電気学会論文誌A. 125-A
• 作者: 住川隆;河森栄一郎;小野靖
• 通讯作者: 小野靖