A peculiar first orbit loss type was found apart from the normal ones when we use ORBIT code to simulate fast ion orbits in the EAST tokamak. Fast ion orbits were studied in the presence of toroidal field （TF） rippl...A peculiar first orbit loss type was found apart from the normal ones when we use ORBIT code to simulate fast ion orbits in the EAST tokamak. Fast ion orbits were studied in the presence of toroidal field （TF） ripple and magnetohydro- dynamic （MHD） perturbations. We analyzed the properties of the drifted orbits in detail and compared their differences, finding that the combined effects of ripple and magnetic islands are much greater than the effects of either one of them alone. Then we investigated the orbitdeviations as a function of pitch angle in different radial positions. The modeling results demonstrate that the loss of trapped particles is mainly caused by the ripple, while MHD＇perturbation mainly plays an important role in the passing particles. Furthermore we modeled the loss rate using different equilibriums. Results prove that a higher beta can indeed improve the confinement of fast ions, while a little change in the q profile can make the topologies of magnetic islands become quite different and results in quite different total particle losses.展开更多
Energetic alpha particle losses with the toroidal field ripple and the Coulomb collision in the CFETR tokamak have been simulated by using the orbit-following code GYCAVA for the steady-state and hybrid scenarios.The ...Energetic alpha particle losses with the toroidal field ripple and the Coulomb collision in the CFETR tokamak have been simulated by using the orbit-following code GYCAVA for the steady-state and hybrid scenarios.The effects of the outer boundary and the ripple amplitude on alpha particle losses have been investigated.The loss fractions and heat loads of alpha particles in the hybrid scenario are much smaller than those in the steady-state scenario for a significant ripple amplitude.Some alpha particles in the plasma core are lost due to the ripple stochastic transport for a large ripple amplitude parameter.The heat loads with the last closed flux surface boundary are different from those with the wall boundary for the CFETR tokamak,which can be explained by typical alpha particle orbits.Discrete heat load spots have been observed in alpha particle loss simulations,which is due to the ripple well loss.The transition of the lost alpha particle behavior from the ripple stochastic diffusion to the ripple well trapping has been identified in our CFETR simulations.The Coulomb collision effect is responsible for this transition.展开更多
基金Project supported by the JSPS-NRF-NSFC A3 Foresight Program in the Field of Plasma Physics(NSFC Grant No.11261140328)
文摘A peculiar first orbit loss type was found apart from the normal ones when we use ORBIT code to simulate fast ion orbits in the EAST tokamak. Fast ion orbits were studied in the presence of toroidal field （TF） ripple and magnetohydro- dynamic （MHD） perturbations. We analyzed the properties of the drifted orbits in detail and compared their differences, finding that the combined effects of ripple and magnetic islands are much greater than the effects of either one of them alone. Then we investigated the orbitdeviations as a function of pitch angle in different radial positions. The modeling results demonstrate that the loss of trapped particles is mainly caused by the ripple, while MHD＇perturbation mainly plays an important role in the passing particles. Furthermore we modeled the loss rate using different equilibriums. Results prove that a higher beta can indeed improve the confinement of fast ions, while a little change in the q profile can make the topologies of magnetic islands become quite different and results in quite different total particle losses.
基金the support from the CFETR teamjointly supported by National Natural Science Foundation of China(Nos.12175034,12005063)+1 种基金the National Key R&D Program of China(No.2019YFE03030001)the Fundamental Research Funds for the Central Universities(No.2232022G-10)。
文摘Energetic alpha particle losses with the toroidal field ripple and the Coulomb collision in the CFETR tokamak have been simulated by using the orbit-following code GYCAVA for the steady-state and hybrid scenarios.The effects of the outer boundary and the ripple amplitude on alpha particle losses have been investigated.The loss fractions and heat loads of alpha particles in the hybrid scenario are much smaller than those in the steady-state scenario for a significant ripple amplitude.Some alpha particles in the plasma core are lost due to the ripple stochastic transport for a large ripple amplitude parameter.The heat loads with the last closed flux surface boundary are different from those with the wall boundary for the CFETR tokamak,which can be explained by typical alpha particle orbits.Discrete heat load spots have been observed in alpha particle loss simulations,which is due to the ripple well loss.The transition of the lost alpha particle behavior from the ripple stochastic diffusion to the ripple well trapping has been identified in our CFETR simulations.The Coulomb collision effect is responsible for this transition.
