First-wall conditioning for enhanced confinement discharges and the DT experiments in TFTR
First-wall conditioning for enhanced confinement discharges and the DT experiments in TFTR
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增强约束放电的第一壁调节和 TFTR 中的 DT 实验
DOI：
10.1016/0022-3115(89)90263-8
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发表时间：
1989
影响因子：
3.1
通讯作者：
M. Zarnstorff
中科院分区：
文献类型：
--
作者：
H. Dylla;M. Ulrickson;M. Bell;D. Owens;D. Buchenauer;R. Budny;K. Hill;S. Kilpatrick;D. Manos;P. Lamarche;A. Ramsey;G. Schmidt;M. Zarnstorff
本文综述了1990-1991年将用于DT实验的TFTR第一壁结构的调节技术。主要感兴趣的是氦调节程序，该程序被开发用于控制来自石墨、内壁缓冲器限制器的类氢循环。对于气体燃料欧姆等离子体，TFTR在等离子体密度范围内运行，n =（2-5）× 10 19 m− 3，通常会导致类氢循环系数接近1。氦调节过程的使用产生了低至0.5的再循环系数，并在I P= 0.8 MA时将最小欧姆等离子体密度降低至n e= 0.5× 10 19 m− 3。低密度欧姆靶等离子体与低再循环条件下的增强约束（例如，“supershot”）的先决条件，中性束加热放电中观察到的TFTR在1986年至1987年，这是主要的模式被认为是在DT实验研究。由氦调节过程引起的再循环变化被认为是由限制器的近表面（< 20 nm）层的类氢物质的He和C离子解吸引起的石墨中的等离子体泵浦效应的结果。比较了有条件限制器泵送气体燃料、弹丸燃料和中性束燃料放电的能力。氦调节技术也有利于同位素交换和最大限度地减少容器内的氚库存。
The conditioning techniques applied to the TFTR first-wall configuration that will be in place for the DT experiments in 1990–1991 are reviewed. Of primary interest is the helium conditioning procedure that was developed to control hydrogenic recycling from the graphite, inner-wall bumper limiter. Operation of TFTR over the plasma density range for gas-fueled ohmic plasmas, n ̄ e=(2–5)× 10 19 m− 3, typically results in hydrogenic recycling coefficients near unity. The use of the helium conditioning procedure produced recycling coefficients as low as 0.5, and decreased the minimum ohmic plasma density to n ̄ e= 0.5× 10 19 m− 3 at I P= 0.8 MA. Low density ohmic target plasmas with low recycling conditions are prerequisite conditions for the enhanced confinement (eg,“supershot”), neutral-beam-heated discharges observed in TFTR during 1986–1987, which is the primary mode being considered for study in the DT experiments. The recycling changes induced by the helium conditioning procedure are believed to be the result of a plasma pumping effect in the graphite induced by He and C ion desorption of hydrogenic species from the near-surface (< 20 nm) layer of the limiter. The capacity of the conditioned limiter to pump gas-fueled, pellet-fueled, and neutral-beam-fueled discharges is compared. The helium conditioning technique is also beneficial for isotopic exchange and for minimizing the in-vessel tritium inventory.