Particle-in-cell simulations have been conducted to investigate the parametric decay processes of radiofrequency waves in the ion cyclotron range of frequency in inhomogeneous plasmas. By choosing the parameters close to those in the ion Bernstein wave heating experiments on the HT-7 tokamak (Li et al 2001 Plasma Phys. Control. Fusion43 1227–38), decay channels similar to experimental observations have been found in simulations. It is shown that due to strong inhomogeneity of tokamak edge plasma, layers may exist where selection rules of the mode–mode coupling are satisfied, and resonant parametric decays can occur if the input wave power is sufficiently high. As a result, daughter waves at half-, second- and third-harmonic frequencies of the pump wave can be excited. The nonresonant parametric decay is also observed, and ions are heated via nonlinear Landau damping.
粒子模拟已被用于研究非均匀等离子体中离子回旋频率范围内射频波的参数衰变过程。通过选择与HT-7托卡马克上离子伯恩斯坦波加热实验（Li等人，2001年，等离子体物理与控制聚变，第43卷，第1227–1238页）相近的参数，在模拟中发现了与实验观测相似的衰变通道。结果表明，由于托卡马克边缘等离子体的强非均匀性，可能存在满足模-模耦合选择定则的层，并且当输入波功率足够高时，可以发生共振参数衰变。结果，可以激发泵波频率的半次、二次和三次谐波处的子波。还观察到了非共振参数衰变，并且离子通过非线性朗道阻尼被加热。