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Research on modeling of peripheral plasma in a field-reversed configuration

场反转配置中的外围等离子体建模研究

基本信息

批准号：
11680492
负责人：
TOMITA Yukihiro
金额：
$ 1.41万
依托单位：
National Institute for Fusion Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

1) The motion of a plasma ion gyrating around separatrix of a field-reversed configuration (FRC) is studied. Numerical studies showed that the action integral of a particle changes abruptly when a particle passes through the vicinity of a field null Xpoint. This phenomena is understood as collisionless stochastic scattering of the pitch angle. In the case of a particle with positive canonical angular momentum Pe, the resultant correlation coefficients of the action integral between before and after the scattering appear to be stochastic in some cases. In this studies the magnetic flux function inside the separatrix is defined positive. As the action integral increases foe a particle with negative PQ, its motion tends to be adiabatic. If the negative PQ of a particle approaches zero, a stochastic motion is observed. 2) The stable sheath formation in an expanding magnetic field to a divertor plate was studied by a one dimensional analysis. The requirement for flow velocity of ions at a plasma-sheath boundary is more restricted than that of the uniform magnetic field, which should be greater than the ion sound speed. The difference, however, between both cases is an order of the Debye length to plasma radius, which is negligibly small. The requirement for ion flow velocity inside a quasi-neutral plasma was obtained by taking into account the effects of the plasma source. Without plasma source in the quasi-neutral plasma, the ion flow velocity at an injection point should be much greater than the ion sound speed. The ion source inside the quasi-neutral plasma, such as electron impact ionization, considerably mitigates this requirement.

1)研究了等离子体离子绕场反转位形分界线的回旋运动。数值研究表明，当粒子通过零场X点附近时，粒子的作用量积分发生突变。这种现象被理解为俯仰角的无碰撞随机散射。在正正则角动量Pe的粒子的情况下，散射前后的作用积分的相关系数在某些情况下似乎是随机的。在本研究中，分界线内的磁通量函数被定义为正。对于具有负PQ的粒子，随着作用量积分的增加，其运动趋于绝热。如果粒子的负PQ接近零，则观察到随机运动。2)本文用一维分析方法研究了偏滤器板在扩展磁场作用下稳定鞘层的形成。对等离子体鞘层边界处的离子流速的要求比均匀磁场的要求更严格，其应大于离子声速。然而，这两种情况之间的差异是德拜长度对等离子体半径的数量级，这是可以忽略不计的小。通过考虑等离子体源的影响，得到了准中性等离子体中离子流速度的要求。在准中性等离子体中没有等离子体源时，注入点处的离子流速应远大于离子声速。准中性等离子体内部的离子源，例如电子碰撞电离，大大减轻了这一要求。