In the experiments of actively triggering plasma disruption by massive gas injection, the externally applied resonant magnetic perturbation has been used to mitigate the hazard of runaway electron(RE). Motivated by th...In the experiments of actively triggering plasma disruption by massive gas injection, the externally applied resonant magnetic perturbation has been used to mitigate the hazard of runaway electron(RE). Motivated by the experiment of multimode coupling to suppress REs on J-TEXT, some typical simulation cases with non-ideal MHD with rotation-open discussion(NIMROD) code are carried out to explore the influential mechanism of different relative phases between m/n =2/1 and m/n = 3/1 magnetic islands on the confinement of REs. Results show that the RE confinement is drastically affected by the relative phase between 2/1 and 3/1 magnetic islands. When the O point phase of 2/1 and 3/1 magnetic islands is toroidal 330°, REs can be effectively lost. The fitting curve of the remaining ratio of REs vs. the relative toroidal phase is predicted to approximate a sine-like function dependence. Further studies indicate that the phase difference between coexisting 2/1 and 3/1 islands can affect the radial transport of impurities. The loss of runaway electrons is closely related to the deposition effect of impurity. The impurity is easier to spread into the core region with smaller poloidal phase difference between the radial velocity of impurity and the impurity quantity of Ar.展开更多
The application of resonant magnetic perturbation(RMP)coils could break the initial axisymmetry and change the magnetic topology in tokamak systems.To understand the plasma equilibrium response to the RMP fields,three...The application of resonant magnetic perturbation(RMP)coils could break the initial axisymmetry and change the magnetic topology in tokamak systems.To understand the plasma equilibrium response to the RMP fields,three-dimensional(3 D)non-linear magnetohydrodynamics equilibrium calculations have been carried out using the HINT code for an RMP field-penetration experiment on J-TEXT.The HINT code does not assume perfectly nested flux surfaces,and is able to consider directly the change of magnetic topology due to the RMP field penetrations.Correlations between 3 D equilibrium calculations and experimental observations are presented.The magnetic topologies calculated by HINT were compared with the field topologies obtained from a vacuum approximation method.It turns out that the effects of redistribution of plasma pressure and current due to the formation of magnetic islands at various resonant rational surfaces should be considered self-consistently for understanding the change of magnetic structure.Such changes include changes in the shape and size of magnetic islands,and the distribution of stochastic fields around the magnetic islands and at the plasma boundary,which plays an important role for plasma-wall interactions.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12175078 and 51821005)
文摘In the experiments of actively triggering plasma disruption by massive gas injection, the externally applied resonant magnetic perturbation has been used to mitigate the hazard of runaway electron(RE). Motivated by the experiment of multimode coupling to suppress REs on J-TEXT, some typical simulation cases with non-ideal MHD with rotation-open discussion(NIMROD) code are carried out to explore the influential mechanism of different relative phases between m/n =2/1 and m/n = 3/1 magnetic islands on the confinement of REs. Results show that the RE confinement is drastically affected by the relative phase between 2/1 and 3/1 magnetic islands. When the O point phase of 2/1 and 3/1 magnetic islands is toroidal 330°, REs can be effectively lost. The fitting curve of the remaining ratio of REs vs. the relative toroidal phase is predicted to approximate a sine-like function dependence. Further studies indicate that the phase difference between coexisting 2/1 and 3/1 islands can affect the radial transport of impurities. The loss of runaway electrons is closely related to the deposition effect of impurity. The impurity is easier to spread into the core region with smaller poloidal phase difference between the radial velocity of impurity and the impurity quantity of Ar.
基金supported by the National Key R&D Program of China(No.2018YFE0309100)by National Natural Science Foundation of China(No.51821005)。
文摘The application of resonant magnetic perturbation(RMP)coils could break the initial axisymmetry and change the magnetic topology in tokamak systems.To understand the plasma equilibrium response to the RMP fields,three-dimensional(3 D)non-linear magnetohydrodynamics equilibrium calculations have been carried out using the HINT code for an RMP field-penetration experiment on J-TEXT.The HINT code does not assume perfectly nested flux surfaces,and is able to consider directly the change of magnetic topology due to the RMP field penetrations.Correlations between 3 D equilibrium calculations and experimental observations are presented.The magnetic topologies calculated by HINT were compared with the field topologies obtained from a vacuum approximation method.It turns out that the effects of redistribution of plasma pressure and current due to the formation of magnetic islands at various resonant rational surfaces should be considered self-consistently for understanding the change of magnetic structure.Such changes include changes in the shape and size of magnetic islands,and the distribution of stochastic fields around the magnetic islands and at the plasma boundary,which plays an important role for plasma-wall interactions.
