Formation of spherical tokamak equilibria by ECH in the LATE device
Formation of spherical tokamak equilibria by ECH in the LATE device
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DOI：
10.1088/0029-5515/45/11/026
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发表时间：
2005-10
期刊：
影响因子：
3.3
通讯作者：
T. Maekawa;Y. Terumichi;H. Tanaka;M. Uchida;T. Yoshinaga;S. Yamaguchi;H. Igami;M. Konno;K. Katsuura;K. Hayashi;Y. Abe;J. Yamada;S. Maebara;T. Imai
中科院分区：
文献类型：
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作者：
T. Maekawa;Y. Terumichi;H. Tanaka;M. Uchida;T. Yoshinaga;S. Yamaguchi;H. Igami;M. Konno;K. Katsuura;K. Hayashi;Y. Abe;J. Yamada;S. Maebara;T. Imai
低纵横比环面实验 (LATE) 装置的主要目标是演示在没有中心螺线管的情况下仅通过电子回旋加速器加热 (ECH) 形成球形环面 (ST) 等离子体，并建立其物理基础。通过注入 2.45 GHz 微波脉冲 4 s，在 Bv = 12 G 的弱稳定垂直场下，P = 5 kW 自发引发 1.2 kA 的等离子体电流，然后随着 Bv 的缓慢上升而缓慢上升，以实现等离子体环路的平衡，最后在 Bv = 70 G 时 P = 30 kW 达到 6.3 kA。该电流相当于线圈总电流的 10%。 60 kA 流过环形场的中心柱。磁测量表明，在放电的最后阶段，已产生并维持了 0.5 s 的 ST 平衡，其最终闭合通量表面的纵横比为 R0/a ≃ 20.4 cm/14.5 cm ≃ 1.4，伸长量为 κ ≃ 1.5，qedge ≃ 37。在稳定 Bv 场下自发形成 ST 平衡也是有效的，其中等离子体电流在几毫秒的时间尺度内快速增加，并且通过 5 GHz 微波脉冲（130 kW，60 ms）自发产生 6.8 kA 的等离子体电流并维持在 Bv = 85 G。在这两种情况下，等离子体中心都位于第二或第三谐波 EC 共振层附近，并且线平均电子密度显着超过等离子体截止密度，这表明模式转换电子伯恩斯坦波的谐波 EC 加热支持等离子体。
The main objective of the Low Aspect Ratio Torus Experiment (LATE) device is to demonstrate the formation of spherical torus (ST) plasmas by electron cyclotron heating (ECH) alone without a centre solenoid and establish its physical bases. By injecting a 2.45 GHz microwave pulse for 4 s, a plasma current of 1.2 kA is spontaneously initiated by P = 5 kW under a weak steady vertical field of Bv = 12 G and then ramped up slowly with a slow ramp-up of Bv for the equilibrium of the plasma loop and finally reaches 6.3 kA by P = 30 kW at Bv = 70 G. This current amounts to 10% of the total coil currents of 60 kA flowing through the centre post for the toroidal field. Magnetic measurements show that an ST equilibrium, having the last closed flux surface with an aspect ratio of R0/a ≃ 20.4 cm/14.5 cm ≃ 1.4, an elongation of κ ≃ 1.5 and qedge ≃ 37, has been produced and maintained for 0.5 s at the final stage of discharge. Spontaneous formation of ST equilibria under steady Bv fields, where plasma current increases rapidly in the time scale of a few milliseconds, is also effective and a plasma current of 6.8 kA is spontaneously generated and maintained at Bv = 85 G by a 5 GHz microwave pulse (130 kW, 60 ms). In both cases, the plasma centre locates near the second or third harmonic EC resonance layer and the line averaged electron density significantly exceeds the plasma cutoff density, suggesting that the harmonic EC heating by the mode-converted electron Bernstein waves supports the plasma.