Improved confinement regime in the current ramp down phase of Frascati tokamak upgrade plasmas
Improved confinement regime in the current ramp down phase of Frascati tokamak upgrade plasmas
复制标题
弗拉斯卡蒂托卡马克升级等离子体当前减速阶段的改进约束机制
DOI：
10.1088/0029-5515/42/11/302
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
L. Gabellieri
中科院分区：
文献类型：
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作者：
M. May;M. Finkenthal;H. Moos;K. Fournier;W. Goldstein;M. Mattioli;D. Pacella;G. Mazzitelli;M. Leigheb;L. Gabellieri
弗拉斯卡蒂托卡马克升级等离子体的电流斜坡下降阶段已被发现表现出非常不同的粒子输运比这是在欧姆加热稳态阶段观察到的。电流斜降阶段的特征在于中心（r/a 0.5），其输运减少2 - 3倍。内部区域的温度随小半径的变化呈类高斯形状。在外部区域中，温度大致具有单一值（~100 eV），没有急剧的梯度，这意味着没有梯度驱动的输运。为了研究粒子输运，通过使用激光吹离技术将铁引入到斜坡下降阶段。用光谱法测量了铁的几种电荷态的时间行为，以确定等离子体中不同空间位置的输运。在斜降阶段的电荷州线发射的时间历程已被观察到衰减慢得多，比在稳态阶段，这意味着在半半径处的传输势垒的存在。杂质电荷状态的行为已经建模与MIST运输代码使用最新的原子物理速率来推断粒子的运输。
The current ramp down phase of the Frascati Tokamak Upgrade plasma has been found to exhibit very different particle transport than that which is observed in the Ohmically heated steady state phase. The current ramp down phase can be characterized by a central (r/a 0.5) that has transport two to three times less. The temperature in the inner region had a Gaussian-like shape as a function of minor radius. In the outer region, the temperature had roughly a single value (~100 eV) with no sharp gradients which implied no gradient driven transport. To study the particle transport, iron was introduced into the ramp down phase by using the laser blow off technique. The time behaviour of several charge states of iron have been measured spectroscopically to determine the transport in the different spatial locations in the plasma. The time histories of the charge state line emission in the ramp down phase have been observed to decay much more slowly than in the steady state phase which implied the existence of a transport barrier at the half radius. The behaviour of the impurity charge states has been modelled with the MIST transport code using up to date atomic physics rates to infer the particle transport.