J-TEXT 学术报告第54期

时 间： 2016年10月20日（周四） 14:00

地 点： 二楼会议室

汇报人1：李复名（HUST）

题目：Detection of high Frequency Magnetic Perturbations using FRMP during Density Limit on the J-TEXT tokamak

摘要：

This report shows the experimental results in last term. The main purpose is to measure the high frequency magnetic perturbations during the themal quench before density limit disruption on J-TEXT tokamak. And the details will be showed in the report . The analysis about the reason of the self-oscillation in the FRMP magnetic signals will also introdued in this report.

汇报人2：刘海（HUST）

题目：The experimental results about the effect of electrode biasing on m/n = 2/1 tearing modes

摘要：

The effects of electrode biasing (EB) on the m/n = 2/1 tearing mode have been experimentally studied in J-TEXT tokamak discharges. It is found that for a negative bias voltage, the mode amplitude is reduced, and the mode frequency is increased accompanied by the increased toroidal plasma rotation speed in the counter-Ip direction. For a positive bias voltage, the mode frequency is decreased together with the change of the rotation velocity towards the co-Ip direction, and the mode amplitude is increased. Statistic results show that the variations in the toroidal rotation speed, the 2/1 mode frequency and its amplitude linearly depend on the bias voltage. The threshold voltages for complete suppression and locking of the mode are found. The experimental results suggest that applied electrode biasing is a possible method for the avoidance of mode locking and disruption.

汇报人3：胡启明（HUST）

题目：Summary of the spring experiment in 2016

摘要：

1) The penetration of m/n=3/1 RMPs is studied in J-TEXT tokamak, it is found that the electron density increases after 3/1 RMP penetration and the spontaneous penetration-unlocking circles happens when the RMP amplitude is not strong enough.

2) Previous experimental results reveal that the negative electrode biasing (EB) can accelerate the plasma rotation and hence stabilize the 2/1 tearing mode. Accordingly, negative EB is proposed to drive the locked island. In the experiment, static RMP is applied firstly to cause locked mode, then negative EB is applied. It is found that strong enough EB can drive the plasma rotation and avoid the mode locking as well as the associated disruption. However, when the mode is completely locked by RMP, it is difficult to unlock the mode. Further studies will be carried out in the coming campaign.

3) It is well know that the RMP penetration threshold depends linearly on plasma rotation. When deceasing the plasma rotation by EB, the penetration threshold will also be decreased. Based on this idea, the penetration threshold is scanned for different EB voltage, and it is found that the penetration threshold depends on the EB voltage. However, the EB is not strong enough to approach the zero penetration threshold.

汇报人4：李建超（HUST）

题目：Experimental results of Study the effect of 1/1 and/or 2/2 RMPs

摘要：

1/1&3/1 RMPs and 2/2 RMPs have been applied to study plasma response. It is observed that precursor m=1 modes have been suppressed slightly by 1/1&3/1 RMPs with n_e>2′10¹⁹m^-3 and q_a~2.3. When 2/2 RMPs are applied, sawtooth period grows with n_e=10¹⁹m^-3 while no effect is observed in case of that with higher density. It is possible that Dy makes influences on sawtooth, which needs more researches.

欢迎各位老师同学参与讨论！