In the HL-2A 2004 experiment campaign, pulsed molecular beam injection (MBI) and strong hydrogen gas puffing under the divertor configuration were used for gas fueling. The experimental results show that the MBI of ...In the HL-2A 2004 experiment campaign, pulsed molecular beam injection (MBI) and strong hydrogen gas puffing under the divertor configuration were used for gas fueling. The experimental results show that the MBI of hydrogen can reduce the heat flux to the divertor target plate. The electron temperature measured by the Langmuir probe array decreases significantly during the injection of the molecular beam whereas the electron density increases. This indicates that the plasma pressure near the target plates tends to be constant at a new equilibrium level. In the divertor plasmas with strong hydrogen gas puffing a high plasma density up to 4.4 × 10^19 m^-3 was achieved. In addition, a phenomenon similar to the partially detached divertor regime was observed, which is being studied in open divertor tokamaks such as DIII-D to reduce the peak heat flux on the target plates near the separatrix. After a strong gas puffing the electron temperature measured on the outer divertor target plate near the separatrix decreases till below 5 eV or even lower, but that of the farther outer divertor target plate does not change obviously; and the CIII and the Ha emissions at the plasma edge decrease as expected, but the Ha emission near the Xpoint increases. These results reflects some interesting characteristics, which needs to be studied by further modeling and experiments.展开更多
One of the critical issues to be solved for HL-2M is the power exhaust.Divertor target plate geometry strongly influences the plasma profiles by controlling the neutral recycling pattern,which in turn has a strong eff...One of the critical issues to be solved for HL-2M is the power exhaust.Divertor target plate geometry strongly influences the plasma profiles by controlling the neutral recycling pattern,which in turn has a strong effect on the symmetry and stability of the divertor plasma and finally on the whole edge region.The numerical simulation SOLPS5.0 package is used to design and explore the divertor target plates for HL-2M.We start with the choice of a proper target plate geometry,which has a smaller incidence angle in the permissible space,and then discuss the method of gas puffing to reduce the heat flux density on the target and the effects of gas puffing on the divertor plasma performance.展开更多
The gas puffing performance plays a key role in repeatable discharges in the Sino- UNited Spherical Tokamak (SUNIST) experiments. In this paper, temporal evolution of the gas pressure in the vacuum vessel and the de...The gas puffing performance plays a key role in repeatable discharges in the Sino- UNited Spherical Tokamak (SUNIST) experiments. In this paper, temporal evolution of the gas pressure in the vacuum vessel and the dependence of the repeatability of plasma discharges on different timing arrangements between the gas puffing pulse and the Ohmic field have been experimentally investigated. The results show that, after a fast rising phase, the gas pressure becomes quasi-stationary. In the regime of the discharges being started up when the gas pressure has already reached the quasi-stationary state for about 37 ms, an improved repeatability of the plasma discharges is achieved.展开更多
The design of the pumping stations and the gas injection systems for the inner Chamber and the cryostat on HT-7U superconducting tokamak is described in this paper.
Recent ion cyclotron resonance frequency(ICRF) coupling experiments for optimizing ICRF heating in high power discharge were performed on EAST. The coupling experiments were focus on antenna phasing and gas puffing,...Recent ion cyclotron resonance frequency(ICRF) coupling experiments for optimizing ICRF heating in high power discharge were performed on EAST. The coupling experiments were focus on antenna phasing and gas puffing, which were performed separately on two ports of the ion cyclotron resonance heating(ICRH) system of EAST. The antenna phasing was performed on the I-port antenna, which consists of four toroidally spaced radiating straps operating in multiple phasing cases; the coupling performance was better under low wave number ∣k;∣(ranging from 4.5 to 6.5). By fuelling the plasma from gas injectors, placed as uniformly spaced array from top to bottom at each side limiter of the B-port antenna, which works in dipole phasing, the coupling resistance of the B-port antenna increased obviously.Furthermore, the coupling resistance of the I-port antenna was insensitive to a smaller rate of gas puffing but when the gas injection rate was more than a certain value(>1021 s;), a sharp increase in the coupling resistance of the I-port antenna occurred, which was mainly caused by the toroidal asymmetric boundary density arising from gas puffing. A more specific analysis is given in the paper.展开更多
基金supported in part by the JSPS-CAS Core University Program in the field of Plasma and Nuclear Fusion
文摘In the HL-2A 2004 experiment campaign, pulsed molecular beam injection (MBI) and strong hydrogen gas puffing under the divertor configuration were used for gas fueling. The experimental results show that the MBI of hydrogen can reduce the heat flux to the divertor target plate. The electron temperature measured by the Langmuir probe array decreases significantly during the injection of the molecular beam whereas the electron density increases. This indicates that the plasma pressure near the target plates tends to be constant at a new equilibrium level. In the divertor plasmas with strong hydrogen gas puffing a high plasma density up to 4.4 × 10^19 m^-3 was achieved. In addition, a phenomenon similar to the partially detached divertor regime was observed, which is being studied in open divertor tokamaks such as DIII-D to reduce the peak heat flux on the target plates near the separatrix. After a strong gas puffing the electron temperature measured on the outer divertor target plate near the separatrix decreases till below 5 eV or even lower, but that of the farther outer divertor target plate does not change obviously; and the CIII and the Ha emissions at the plasma edge decrease as expected, but the Ha emission near the Xpoint increases. These results reflects some interesting characteristics, which needs to be studied by further modeling and experiments.
基金supported by the National Magnetic Confinement Fusion Science Program of China(No.2009GB104008)National Natural Science Foundation of China(Nos.10975048,11175061)
文摘One of the critical issues to be solved for HL-2M is the power exhaust.Divertor target plate geometry strongly influences the plasma profiles by controlling the neutral recycling pattern,which in turn has a strong effect on the symmetry and stability of the divertor plasma and finally on the whole edge region.The numerical simulation SOLPS5.0 package is used to design and explore the divertor target plates for HL-2M.We start with the choice of a proper target plate geometry,which has a smaller incidence angle in the permissible space,and then discuss the method of gas puffing to reduce the heat flux density on the target and the effects of gas puffing on the divertor plasma performance.
基金supported by National Natural Science Foundation of China(Nos.10990214,11175103,11261140327 and 11075092)Ministry of Science and Technology(MOST)of China(Nos.2013GB112001 and 2010GB107002)Tsinghua University Initiative Scientific Research Program
文摘The gas puffing performance plays a key role in repeatable discharges in the Sino- UNited Spherical Tokamak (SUNIST) experiments. In this paper, temporal evolution of the gas pressure in the vacuum vessel and the dependence of the repeatability of plasma discharges on different timing arrangements between the gas puffing pulse and the Ohmic field have been experimentally investigated. The results show that, after a fast rising phase, the gas pressure becomes quasi-stationary. In the regime of the discharges being started up when the gas pressure has already reached the quasi-stationary state for about 37 ms, an improved repeatability of the plasma discharges is achieved.
文摘The design of the pumping stations and the gas injection systems for the inner Chamber and the cryostat on HT-7U superconducting tokamak is described in this paper.
基金National key Research and Development program (Grant Nos. 2016YFA0400600 and 2016YFA0400601)National Magnetic Confinement Fusion Science Programme (Grant Nos. 2015GB101001 and 2013GB106001B)+1 种基金National Natural Science Foundation of China under Grant Nos. 11375235, 11675213 and 11375236JSPS-NRF-NSFC A3 Foresight Program in the field of Plasma Physics (NSFC no. 11261140328)
文摘Recent ion cyclotron resonance frequency(ICRF) coupling experiments for optimizing ICRF heating in high power discharge were performed on EAST. The coupling experiments were focus on antenna phasing and gas puffing, which were performed separately on two ports of the ion cyclotron resonance heating(ICRH) system of EAST. The antenna phasing was performed on the I-port antenna, which consists of four toroidally spaced radiating straps operating in multiple phasing cases; the coupling performance was better under low wave number ∣k;∣(ranging from 4.5 to 6.5). By fuelling the plasma from gas injectors, placed as uniformly spaced array from top to bottom at each side limiter of the B-port antenna, which works in dipole phasing, the coupling resistance of the B-port antenna increased obviously.Furthermore, the coupling resistance of the I-port antenna was insensitive to a smaller rate of gas puffing but when the gas injection rate was more than a certain value(>1021 s;), a sharp increase in the coupling resistance of the I-port antenna occurred, which was mainly caused by the toroidal asymmetric boundary density arising from gas puffing. A more specific analysis is given in the paper.