High beta plasma confinement study on a small torus device with a floating high temperature superconductor coil

我们的目标是在一个带有高温超导线圈的小型环面装置上研究高β等离子体。从等离子体实验和器件操作的角度出发，我们采用了一种高温超导电缆Bi-2223，与低温超导体相比，它具有更大的热容量。这是高温超导线圈应用于聚变等离子体器件的第一个挑战，高温超导线圈的反馈悬浮几乎没有挑战。我们已经开始了内部线圈设备Mini-RT的几个研发问题；例如，用微型装置FB-RT进行悬浮的演示，持续电流开关（PCS）的设计和制造以及持续电流操作的演示，以及可拆卸转移管和电流馈通的开发。在Mini-RT装置中，我们成功地在一小时内以10微米的精度悬浮高温超导体线圈。由于内部线圈周围的典型磁场为0.1T，因此采用2.45 GHz的微波电子回旋加热（ECH）产生并加热等离子体。等离子体密度为（5-7）× 10^<16> m^<-3>，达到微波的截止密度。密度曲线在内部线圈附近有一个峰值。电子温度为10 eV，离子温度为1 eV。

We are aiming at studying high-beta plasmas on a small torus device with a high temperature superconductor coil. From the viewpoint of plasma experiment and device operation, we have employed a high temperature superconducting cable Bi-2223, which has a large heat capacity in comparison with a low temperature superconductor. This is a first challenge for applying the high temperature superconductor coil in fusion plasma devices, and there are few challenges for the feedback levitation of the high temperature superconductor coil.We have started several R&D issues for the internal coil device Mini-RT ; e.g., the demonstration of the levitation with the miniature device FB-RT, the design and fabrication of the persistent current switch (PCS) and the demonstration of the persistent current operation, and developments of demountable transfer tube and current feed-through.In the Mini-RT device, we have successfully levitated the high temperature superconductor coil with an accuracy of 10 micrometer during a hour. Since the typical magnetic field is 0.1T around the internal coil, the plasma is produced and heated by the Electron Cyclotron Heating (ECH) with the microwave of 2.45 GHz. The plasma density is (5-7)x10^<16> m^<-3>, and is reaching at the cut-off density of the microwave. The density profile has a peak near the internal coil. The electron and ion temperatures are 10 eV and 1 eV, respectively.