Formation and Sustainment of Spherical Tokamak by Electron Cyclotron Heating

电子回旋加热球形托卡马克的形成和维持

• 批准号: 13480125
• 负责人: TANAKA Hitoshi
• 金额: $ 5.63万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13480125/
• 关键词: Spherical Tokamak; Electron Bernstein Wave; Electron Cyclotron Heating; モード変換

Experiments on start-up and formation of spherical tokamak plasmas were carried out on the LATE device by electron cyclotron heating alone without Ohmic heating, and following results were obtained.[1] A plasma current UP to 3 kA was generated and maintained for 1 sec by injecting a 2.45 GHz, 5 kW microwave power. Magnetic measurement showed that closed flux surfaces were formed. The electron density was more than the plasma cutoff density, suggesting that electron Bernstein wave (EBW) heating occurred.[2] In order to form closed flux surfaces, it was necessary that (1) the gas pressure was 2 - 4 x 10^<-3> Pa, and that (2) the n index of the vacuum vertical magnetic field was more than 0.18.[3] The mechanism of current drive before formation of closed flux surfaces were investigated on the basis of electron density and temperature profiles measured by electrostatic probes. Th estimated value of driven current was in fairly good agreement with the observed value.[4] By injecting 2GHz/0.1s, 50 kW microwave pulse and increasing the vertical magnetic field after formation of closed flux surfaces, the plasma current increased up to 5 kA. The strength of the vertical field had to be controlled to maintain the MHD equilibrium. Additional gas puffing during the discharge increased the density more than 6 times the cutoff density.[5] We found the method to calculate the polarization of incident electromagnetic waves which maximized the mode conversion efficiency to EBW for arbitrary density gradient and injection angle, and made the calculation code. The new result was obtained that the mode conversion efficiency more than 90 % can be obtained by optimizing the polarization even in the condition where previous theory predicted bad conversion efficiency.

在LATE装置上进行了无欧姆加热的电子回旋加热球形托卡马克等离子体的启动和形成实验，得到了以下结果。[1]通过注入2.45 GHz、5 kW的微波功率，产生高达3 kA的等离子体电流并维持1秒。磁测量表明，封闭的磁通表面形成。电子密度大于等离子体截止密度，表明发生了电子伯恩斯坦波（EBW）加热。[2]为了形成封闭的磁通表面，必须（1）气体压力为2 - 4 × 10 - 4 <-3>Pa，（2）真空垂直磁场的n指数大于0.18。[3]根据静电探针测量的电子密度和温度分布，研究了封闭磁通面形成前的电流驱动机制。驱动电流的估算值与实测值吻合较好。[4]通过注入2GHz/0.1s，50 kW的微波脉冲，并在形成闭合磁通面后增加垂直磁场，等离子体电流增加到5 kA。必须控制垂直场的强度以保持MHD平衡。放电过程中额外的气体喷吹使密度增加到截止密度的6倍以上。[5]找到了在任意密度梯度和入射角下，使模式转换效率最大的入射电磁波偏振态的计算方法，并编制了计算程序。得到了新的结果，即使在以前的理论预测转换效率差的情况下，通过优化偏振也可以获得90%以上的模式转换效率。

项目成果

田中仁, 檜垣謙一, 吉永智一, 伊神弘恵, 打田正樹, 前川孝: "LATEにおけるECH電流駆動実験"電気学会研究会資料. PST-01-75. 53-57 (2001)

Hitoshi Tanaka、Kenichi Higaki、Tomokazu Yoshinaga、Hiroe Igami、Masaki Uchida、Takashi Maekawa：“ECH 电流驱动实验”IEEJ 研究组材料（2001 年）。

H.Tanaka, K.Higaki, T.Yoshinaga, H.Igami, M.Uchida.T.Maekawa: "Formation of ECH Spherical Tokamak on LATE"Proc. 29^<th> EPS Conf. on Plasma Phys. and Contr. Fusion, Montreu, Switzerland. P-5.050 (2002)

H.Tanaka、K.Higaki、T.Yoshinaga、H.Igami、M.Uchida.T.Maekawa：“ECH 球形托卡马克在 LATE 上的形成”Proc。

M.Uchida, K.Higaki, T.Yoshinaga, H.Igami, H.Tanaka, T.Maekawa: "Formation and Sustainment of Low Aspect Ratio Torus Plasma by ECH in the LATE Device"J. Plasma Fusion Res. SERIES. 5(印刷中).

M.Uchida、K.Higaki、T.Yoshinaga、H.Igami、H.Tanaka、T.Maekawa：“LATE 装置中 ECH 的低纵横比环面等离子体的形成和维持”J。 （在新闻）。

H. Tanaka, K. Higaki, T. Yoshinaga, H. Igami, M. Uchida, T. Maekawa: "Experiment of ECH Current Start-up and Sustainment on LATE"Supplements for Workshop of IEEJ. PST-01-75 (in Japanese). 53-57 (2001)

H. Tanaka、K. Higaki、T. Yoshinaga、H. Igami、M. Uchida、T. Maekawa：“ECH 当前启动和 LATE 维持实验”IEEJ 研讨会补充材料。

T.Maekawa, H.Tanaka, M.Uchida, H.Igami, T.Yoshinaga.K.Higaki: "Start-up and Formation of ST Plasmas by ECH on the LATE Device"Proc. 19^<th> IAEA Fusion Energy Conf., Lyon, France. IAEA-CN-94/EX/P4-16 (2002)

T.Maekawa、H.Tanaka、M.Uchida、H.Igami、T.Yoshinaga.K.Higaki：“在 LATE 设备上通过 ECH 启动和形成 ST 等离子体”Proc。