Influence of ion cyclotron range of frequencies heating on neutron emission rate in HL-3 tokamak

Abstract

BackgroundIon cyclotron range of frequencies (ICRF) heating is one of the most widely used auxiliary heating methods in tokamaks. The HL-3 tokamak plans to equip a 6 MW ICRF heating system to conduct discharge experiments of high-performance plasma.PurposeThis study optimizes the parameters of ICRF using numerical simulations with the purpose of supporting the reactor-level plasma in HL-3 in future.MethodsOn the basis of NBI heating in the HL-3 device, ICRF heating was considered, and the TRANSP code was employed to explore the influence of ICRF frequency and power in HL-3 on the neutron emission rate, as well as the distribution of fast ions. The ICRF frequency range was between 25 MHz and 40 MHz, and the ICRF power range was between 1 MW and 6 MW. The neutron signals based on the concept of neutron camera diagnosis were also simulated.ResultsThe simulation results show that the ICRF frequency and power significantly influence the neutron emission rate. The neutron emission rate is directly proportional to the ICRF heating power at a fixed ICRF frequency whilst the increase in the neutron emission rate significantly depends on the ICRF frequency when the ICRF heating power is fixed. Among the investigated parameters, the ICRF with a frequency of 30 MHz yields the maximum increase in the neutron emission rate. The simulation results of fast ions demonstrate that the synergetic heating of neutral beam injection and ICRF can heat fast ions up to 1 MeV after considering ICRF heating, which effectively increases the neutron emission rate. The simulation results of neutron camera indicate that neutron camera can effectively measure the changes in neutron emission rate and distribution profile caused by ICRF heating.ConclusionsThe simulation results demonstrate that the appropriate selection of the ICRF frequency and power can effectively increase the neutron emission rate in HL-3 experiments, the optimal combination of ICRF frequency/power is 30 MHz/6 MW for the scenario analyzed in this study. The simulation of neutron camera for HL-3 provides a reference for designing future neutron camera systems and measuring neutron spatial distributions.

Keywords

• ion cyclotron range of frequencies
• fusion neutrons
• fast ions
• hl-3 tokamak