First EC-DC on HT-7

X. GAO, Y. W. YU, Y. YANGMay 1, 2007

Outline

Investigation Parameters Procedure Diagnostics Prospect

Investigation ECRF (Electron Cyclotron Range of Frequencies) may be u

sed for heating, non-inductive current drive, start-up and burn-though, plasma control, and wall conditioning.

The reference process for wall conditioning involves … and EC-DC or IC-DC (see below) with toroidal field using D2 and He.－ ITER Technical Basis (PDD2-7)

Investigation

B∅=B0R0/R

ω=neB∅/me

Radial plasma density profile,ne ~ zero at R < Rresonance;

nearly constant density ~ 1016

m-3 at R > Rresonance.

ion flux or “plasma loss” is distributed over a very large area of the wall at R > Rresonance.

--Alcator C-Mod Mini-Proposal

Investigation

C-Mod: localize B film growth to

a) produce thicker B films on the outer divertor shelf for a given duration of ECDC

b) avoid B film growth in the antennae. in-situ tile conditioning and surface heating

--Alcator C-Mod Mini-Proposal (2007)

Investigation

TRIAM-1M the wall conditioned by only ECR-DC is good in

both OH and LHCD plasmas. ECR-DC has no problems with thermal insulation

and is suitable for operation in a steady magnetic field.

--Wall conditioning using 2.45 GHz ECR-DC on superconducting tokamak TRIAM-1M

Parameters Parameters (HT-7 Apr. 30, 2007):

Working Gas Species: Helium Toroidal Field: ~0.09 T(~200A) Vertical Field: No Pressure: 1.3E-2 Pa RF Power: 10 KW, 8 KW

Diagnostics QMS （王厚银） OMA （符佳、王光祺）

Procedure （一） 内真空室用＃ 1 机组分子泵，其他全部关闭 设定充气压强 1.3E-3 Pa ，冲入氦气 投入 LHW10 KW 等离子体点亮并持续 10 分钟

Procedure （二） 保持其他参数不变，降低 LHW 功率至 8 KW 等离子体点亮 持续 9 分钟后因 LHW 电源故障停止

Diagnostics-Video 等离子体被点亮 等离子体位于低场侧

Side view Top view

LFSHFS

Diagnostics -QMS

10 KW 8 KW

清洗效果不明显

Diagnostics -QMS

真空室内气体成分前后比较

Diagnostics-OMA

Diagnostics-OMA

在硼化过程中出现了明显的 H 峰，而 ECRH 中的 H 峰不明显

Preliminary results

实现了 LHW D.C. 用于清洗的参数有待优化 观察到有利于硼化控制的局域化的等离子体

Prospect

清洗 改变纵场强度 调整气压 加入垂直场

硼化 尝试用于硼化