Density limits in TEXTOR-94 auxiliary heated discharges
Density limits in TEXTOR-94 auxiliary heated discharges
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DOI：
10.1088/0029-5515/39/6/305
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发表时间：
1999-06
期刊：
影响因子：
3.3
通讯作者：
J. Rapp;P. Vries;F. C. Schüller;M. Tokar;W. Biel;R. Jaspers;H. Koslowski;A. Krämer-Flecken;A. Kreter;M. Lehnen;A. Pospieszczyk;D. Reiser;U. Samm;G. Sergienko
中科院分区：
文献类型：
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作者：
J. Rapp;P. Vries;F. C. Schüller;M. Tokar;W. Biel;R. Jaspers;H. Koslowski;A. Krämer-Flecken;A. Kreter;M. Lehnen;A. Pospieszczyk;D. Reiser;U. Samm;G. Sergienko
在托卡马克等离子体中，可达到的最大密度是有限的。密度太高将导致放电剧烈结束。可以区分两种类型的密度极限破坏：(a) 如果辐射功率超过输入功率，则不纯且适度加热的放电；(b) 清洁的辅助加热放电，其中遇到格林沃尔德极限。人们发现，在 TEXTOR-94 中，这两个密度限制因等离子体边界中的辐射不稳定性而不同，而等离子体边界在破坏之前。在第一种类型之前观察到对称的辐射地幔和脱离，而格林沃尔德极限有一个 MARFE 前兆。对杂质含量、边缘和回收特性的控制可防止 MARFE 的生长，并使 TEXTOR-94 中的格林沃尔德极限超过 2 倍以上。通过正常供气方式获得了高密度。已获得最大中心密度 ne(0) = 1.3 × 1020 m-3。可实现的最大密度与输入功率和等离子体电流成比例。 L 模式下产生了无中断放电，其静态 (t > 25 τE) 密度比格林沃尔德极限高出 1.93 倍。在整个高密度阶段，辐射损耗和杂质浓度一直保持在相对较低的水平。
In a tokamak plasma the maximum achievable density is limited. A too high density will result in a violent end of a discharge. Two types of density limit disruption can be distinguished: (a) impure and moderately heated discharges, if the radiative power exceeds the input power, (b) clean, auxiliary heated discharges, where the Greenwald limit is encountered. It has been found that in TEXTOR-94 these two density limits differ by the radiative instability in the plasma boundary, which preceeds the disruption. A symmetric radiative mantle and a detachment are observed prior to the first type, while the Greenwald limit has a MARFE precursor. Control of the impurity content, edge and recycling properties prevents the growth of the MARFE and makes it possible to exceed the Greenwald limit in TEXTOR-94 by more than a factor of 2. High densities have been obtained by means of normal gas feed. Maximum central densities of ne(0) = 1.3 × 1020 m-3 have been obtained. The maximum achievable density scales with the input power and plasma current. Non-disruptive discharges, with a stationary (t > 25 τE) density a factor of 1.93 above the Greenwald limit have been produced in L mode. The radiative losses and impurity concentration have been maintained at a relatively low level during the entire high density phase.