The rapid response of 2/1 tearing mode to electrode biasing in J-TEXT experiments

Wang, Tong; Chen, Zhipeng; Hu, Qiming; Liu, Hai; Yu, Q.; Yang, Jie; Huang, Mingxiang; Li, Da; Shen, Chengshuo; Huang, Yuan; Xia, Minghui; Cheng, Zhifeng; Gao, Li; Zhang, Yang; Zhu, Lizhi; Ding, Yonghua; Wang, Nengchao; Shi, Peng; Zhuang, G.; Liang, Yun-Feng

doi:10.1088/1361-6587/ab1470

Cited by 3 publications

(4 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…If the EB current is sufficiently negative, the local plasma as well as the 3/1 mode is forced to rotate, which will in turn pull the locked 2/1 mode toward mode unlocking via mode coupling. This mechanism is distinctive with those mentioned before, and could be response for the fast response of mode frequency to EB current shown in figure 2 and the experimental results in the previous work [39,40] . In general, the interaction between the locked island and RMP can be seen as braking torque in the unlocking process, while the interaction between the locked island and EB as driving torque.…”

Section: Discussionsupporting

confidence: 76%

“…No delay in the change of the locked mode phase is seen from figure 1(c) after the EB current is turned on. Such a fast response of the 2/1 mode to EB current is more evident in experiments without applying RMPs [39,40]. An experimental example is shown in figure 2 with I P = 150 kA, B t = 1.6 T, n e = 1.3 × 10 19 m −3 .…”

Section: Unlocking Locked Modementioning

confidence: 80%

“…In J-TEXT tokamak， an electrode biasing (EB) system has been designed and constructed [37] , which is used to improve confinement and drive local rotation at plasma edge. The previous works show that the application of EB can not only enhance the constraint of edge turbulence by the radial Er [38] , but also modulate the tearing mode frequency to stable or unstable state [39,40] .…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

First observation of unlocking the locked mode by electrode biasing on J-TEXT tokamak

Chen¹,

Wang²,

et al. 2020

Nucl. Fusion

Self Cite

View full text Add to dashboard Cite

Major disruptions, often caused by locked m/n = 2/1 modes (m/n is the poloidal/toroidal mode number), are great threat to a tokamak fusion reactor and should be mitigated or avoided. The locked 2/1 modes have been unlocked by electrode biasing (EB) for the first time in J-TEXT tokamak experiments. The application of a sufficiently negative EB voltage in plasma edge region quickly changes the phase and amplitude of the locked 2/1 mode and drives the mode to rotate in about 10–30 ms. For a larger EB current or a smaller locked mode amplitude, the mode is more easily to be unlocked, revealing a new method for mode unlocking and avoiding plasma disruptions.

show abstract

Section: Discussionsupporting

confidence: 76%

Section: Unlocking Locked Modementioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

First observation of unlocking the locked mode by electrode biasing on J-TEXT tokamak

Chen¹,

Wang²,

et al. 2020

Nucl. Fusion

Self Cite

View full text Add to dashboard Cite

show abstract

“…References [38][39][40] show that mode-locking and disruptions can be mitigated by the application of an electrode biasing. Observations of Wang et al [41] show that a rapid response of the 2/1 tearing mode to electrode biasing is a possible method of avoidance of mode locking and disruption. Runway electrons also could be controlled by the application of electrode biasing [18,42].…”

Section: Introductionmentioning

confidence: 99%

Edge biasing and its impact on the edge and SOL turbulence

Shankar¹,

Bisai²,

Raj³

et al. 2022

Nucl. Fusion

View full text Add to dashboard Cite

A theoretical study is made of the effect of edge biasing on the dynamics of the interchange turbulence in the edge and scrape-off layer (SOL) regions. A linear analysis of a set of model fluid equations shows that biasing stabilizes the small ky modes. The model equations are next solved numerically, using the BOUT++ framework, to explore the nonlinear dynamics in the presence of positive or negative bias and compared to results in the absence of bias. Positive biasing is found to lead to a larger increment in plasma density and temperature as compared to negative biasing. It is further observed that cross-correlation between density and poloidal electric field at different radial positions decreases for positive biasing and in the case of negative biasing it is almost similar to that of no biasing. Plasma density and poloidal electric field fluctuations have been investigated which show that the density fluctuations increase (decrease) for positive (negative) biasing but the radially outward flux for these biasing cases always decreases mainly due to the decrease of cross-correlation between density and poloidal electric field fluctuations.

show abstract

Controlling the rotation of drift tearing modes by biased electrode in ADITYA-U tokamak

et al. 2021

View full text Add to dashboard Cite

The influence of background plasma poloidal rotation on the rotation frequency of the m/n = 2/1 drift tearing mode (DTM) has been studied in ADITYA-U tokamak. The poloidal rotation velocity of the background plasma in the ion diamagnetic direction is increased or decreased by inducing an outward or inward radial electric field, respectively, through a biased-electrode placed in the edge region of the plasma. The rotation frequency of the preexisting drift tearing mode, rotating in the electron diamagnetic direction, concomitantly decreased or increased with the application of bias depending on its polarity. The positive-bias increases the background plasma rotation in the ion-diamagnetic direction from its pre-bias value, hence decreasing the DTM rotation frequency, whereas the negative bias reduces the plasma rotation velocity in the ion-diamagnetic direction, hence increasing the mode rotation. In addition to that, a short gas puff introduced during the positive and negative bias pulse further reduces the mode frequency, however, with different amplitudes in different bias-polarities. These observations suggest that the background plasma rotation contributes significantly toward the rotation of DTMs, and the rotation frequency of the magnetohydrodynamic modes can be modified by varying the poloidal rotation of the background plasma and/or the diamagnetic drift frequency.

show abstract

The rapid response of 2/1 tearing mode to electrode biasing in J-TEXT experiments

Cited by 3 publications

References 38 publications

First observation of unlocking the locked mode by electrode biasing on J-TEXT tokamak

First observation of unlocking the locked mode by electrode biasing on J-TEXT tokamak

Edge biasing and its impact on the edge and SOL turbulence

Controlling the rotation of drift tearing modes by biased electrode in ADITYA-U tokamak

Contact Info

Product

Resources

About