Effects of CT injector acceleration electrode configuration on tokamak penetration
Effects of CT injector acceleration electrode configuration on tokamak penetration
复制标题
CT喷射器加速电极配置对托卡马克穿透力的影响
DOI：
10.1088/0029-5515/38/5/306
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发表时间：
1998
期刊：
影响因子：
3.3
通讯作者：
P. Bellan
中科院分区：
文献类型：
--
作者：
J. Yee;P. Bellan
通过 TEXT-U 托卡马克（BT simeq 10 kG 和 IP simeq 100 kA）上的紧凑环形（CT）注入实验表明，加速电极配置，特别是托卡马克环形场（TF）线圈附近的加速电极配置，对穿透性能有很大影响。在最初的实验中，在异常低的 TF 强度下，注射器内的 CT 过早停止。我们发现两项修改可以极大地提高性能：(a) 去除一部分内电极和 (b) 增加“漂移管”的直径（加速后引导 CT 进入托卡马克）。有人提出，减慢 CT 速度的主要阻力机制是环形通量捕获，当 CT 取代加速电极（或漂移管）通量守恒壁内捕获的横向 TF 时，就会发生这种情况。对于简单的二维 (2-D) 几何结构，静磁分析产生的 CT 动能要求为 1/2ρv2 ≥ α(B02/2μ0)，其中 α = 2/(1-a2/R2) 是一个无量纲数，取决于由漂移管半径 R 归一化的 CT 半径 a。对于典型的 CT，这可以大大增加所需的能量。 3-D 数值分析证实了长 CT 的分析结果（长度 L 使得 L/a gtrsim 10）。除了磁通捕获之外，CT 形状也会影响能量准则。这些发现表明，对 CT 穿透特定托卡马克 TF 所需动能的实际评估必须考虑磁场与注入器电极壁的相互作用。
Through compact toroid (CT) injection experiments on the TEXT-U tokamak (with BT simeq 10 kG and IP simeq 100 kA), it has been shown that the acceleration electrode configuration, particularly in the vicinity of the toroidal field (TF) coils of the tokamak, has a strong effect on penetration performance. In initial experiments, premature stopping of CTs within the injector was seen at anomalously low TF strengths. Two modifications were found to greatly improve performance: (a) removal of a section of the inner electrode and (b) increased diameter of the 'drift tube' (which guides the CT into the tokamak after acceleration). It is proposed that the primary drag mechanism slowing CTs is toroidal flux trapping, which occurs when a CT displaces transverse TF trapped within the flux conserving walls of the acceleration electrodes (or drift tube). For a simple two dimensional (2-D) geometry, a magnetostatic analysis produces a CT kinetic energy requirement of 1/2ρv2 ≥ α(B02/2μ0), with α = 2/(1-a2/R2) a dimensionless number that is dependent on the CT radius a normalized by the drift tube radius R. For a typical CT, this can greatly increase the required energies. A numerical analysis in 3-D confirms the analytical result for long CTs (with length L such that L/a gtrsim 10). In addition to flux trapping, the CT shape is also shown to affect the energy criterion. These findings indicate that a realistic assessment of the kinetic energy required for a CT to penetrate a particular tokamak TF must take into account the interaction of the magnetic field with the electrode walls of the injector.