The main works on disruption mitigation including suppression and mitigation of runaway current on the J-TEXT tokamak are summarized in this paper.Two strategies for the mitigation of runaway electron(RE) beams are ap...The main works on disruption mitigation including suppression and mitigation of runaway current on the J-TEXT tokamak are summarized in this paper.Two strategies for the mitigation of runaway electron(RE) beams are applied in experiments.The first strategy enables the REs to be completely suppressed by means of supersonic molecular beam injection and resonant magnetic perturbation which can enhance RE loss,magnetic energy transfer which can reduce the electric field,and secondary massive gas injection(MGI) which can increase the collisional damping.For the second strategy,the runaway current is allowed to form but should be dissipated or soft landed within tolerance.It is observed that the runaway current can be significantly dissipated by MGI,and the dissipation rate increases with the injected impurity particle number and eventually stabilizes at 28 MA s^(-1).The dissipation rate of the runaway current can be up to 3 MA s^(-1)by ohmic field.Shattered pellet injection has been chosen as the main disruption mitigation method,which has the capability of injecting material deeper into the plasma for higher density assimilation when compared to MGI.Moreover,simulation works show that the RE seeds in the plasma are strongly influenced under different phases and sizes of 2/1 mode locked islands during thermal quench.The robust runaway suppression and runaway current dissipation provide an important insight on the disruption mitigation for future large tokamaks.展开更多
Recently,experimental studies on the soft landing of RE current by ohmic(OH)field have been performed in J-TEXT tokamak,as a possible auxiliary method to dissipate the RE current.With optimized horizontal displacement...Recently,experimental studies on the soft landing of RE current by ohmic(OH)field have been performed in J-TEXT tokamak,as a possible auxiliary method to dissipate the RE current.With optimized horizontal displacement control of the RE beam,the toroidal electric field has been scanned from 1.6 to—0.3 V m^-1 during the RE plateau phase.The growth rate of RE currents and the evolution of hard x-ray(HXR)emissions have been studied.It is found that when the toroidal electric field is less than 7-12 times the theoretical critical electric field,the decay of REs could be achieved.The dissipation rate by the ohmic field can reach a maximum value of 3 MA s^-1.Furthermore,the results of HXR spectra analysis indicate the different behaviors of HXR emissions under the condition of different toroidal electric fields.The analysis of the ionized argon emissions and magnetic fluctuations shows that under the condition of different toroidal electric fields,the physical process of RE generation may be different.展开更多
基金supported by the National MCF Energy R&D Program of China(Nos.2019YFE03010004,2018YFE0309103,2018YFE0310300,2018YFE0309100,2017YFE0302000,2017YFE0300501)National Natural Science Foundation of China(Nos.11775089,51821005,12205122,11905077 and 11575068)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.21KJB140025)
文摘The main works on disruption mitigation including suppression and mitigation of runaway current on the J-TEXT tokamak are summarized in this paper.Two strategies for the mitigation of runaway electron(RE) beams are applied in experiments.The first strategy enables the REs to be completely suppressed by means of supersonic molecular beam injection and resonant magnetic perturbation which can enhance RE loss,magnetic energy transfer which can reduce the electric field,and secondary massive gas injection(MGI) which can increase the collisional damping.For the second strategy,the runaway current is allowed to form but should be dissipated or soft landed within tolerance.It is observed that the runaway current can be significantly dissipated by MGI,and the dissipation rate increases with the injected impurity particle number and eventually stabilizes at 28 MA s^(-1).The dissipation rate of the runaway current can be up to 3 MA s^(-1)by ohmic field.Shattered pellet injection has been chosen as the main disruption mitigation method,which has the capability of injecting material deeper into the plasma for higher density assimilation when compared to MGI.Moreover,simulation works show that the RE seeds in the plasma are strongly influenced under different phases and sizes of 2/1 mode locked islands during thermal quench.The robust runaway suppression and runaway current dissipation provide an important insight on the disruption mitigation for future large tokamaks.
基金supported by the National Key R&D Program of China(No.2017YFE0302000)the National Magnetic Confinement Fusion Science Program of China(Nos.2015GB111002,2015GB104000)+1 种基金National Natural Science Foundation of China(Nos.11775089,51821005,71762031,11575068,11905077)the China Postdoctoral Science Foundation(2019M652615)。
文摘Recently,experimental studies on the soft landing of RE current by ohmic(OH)field have been performed in J-TEXT tokamak,as a possible auxiliary method to dissipate the RE current.With optimized horizontal displacement control of the RE beam,the toroidal electric field has been scanned from 1.6 to—0.3 V m^-1 during the RE plateau phase.The growth rate of RE currents and the evolution of hard x-ray(HXR)emissions have been studied.It is found that when the toroidal electric field is less than 7-12 times the theoretical critical electric field,the decay of REs could be achieved.The dissipation rate by the ohmic field can reach a maximum value of 3 MA s^-1.Furthermore,the results of HXR spectra analysis indicate the different behaviors of HXR emissions under the condition of different toroidal electric fields.The analysis of the ionized argon emissions and magnetic fluctuations shows that under the condition of different toroidal electric fields,the physical process of RE generation may be different.
