Simulation of the Plasma Density Evolution during Electron Cyclotron Resonance Heating at the T-10 Tokamakстатья
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Дата последнего поиска статьи во внешних источниках: 29 мая 2019 г.
Аннотация:In ohmically heated (OH) plasma with low recycling, an improved particle confinement (IPC)
mode is established during gas injection. However, after gas injection is switched off, this mode is retained only for about 100 ms, after which an abrupt phase transition into the low particle confinement (LPC) modeoccurs in the entire plasma cross section. During such a transition, energy transport due to heat conductiondoes not change. The phase transition in OH plasma is similar to the effect of density pump-out from theplasma core, which occurs after electron cyclotron heating (ECH) is switched on. Analysis of the measured
plasma pressure profiles in the T-10 tokamak shows that, after gas injection in the OH mode is switched off,the plasma pressure profile in the IPC stage becomes more peaked and, after the peakedness exceeds a certain critical value, the IPC−LPC transition occurs. Similar processes are also observed during ECH. If the pressure profile is insufficiently peaked during ECH, then the density pump-out effect comes into play only after the critical peakedness of the pressure profile is reached. In the plasma core, the density and pressure profiles are close to the corresponding canonical profiles. This allows one to derive an expression for the particle flux within the canonical profile model and formulate a criterion for the IPC−LPC transition. The time evolution of the plasma density profile during phase transitions was simulated for a number of T-10 shots with ECH and high recycling. The particle transport coefficients in the IPC and LPC phases, as well as the dependences of these coefficients on the ECH power, are determined.