Particle Simulation Of Non-resonant Heating Plasmas By Low-Frequency Alfvén Waves

The interaction of Alfvén waves and charged particles is a very important researchtopic in controlled fusion plasma physics and space plasma physics. It’s usuallybelieved that the effect of non-resonant interaction between low-frequency Alfvénwaves and charged particles is very small in the low-beta plasma. Considering thehigher order nonlinear effect, the effect of non-resonant interaction betweenlow-frequency Alfvén waves and charged particles will not be negligible. In thispaper, we study the non-resonant heating of plasmas via low-frequency Alfvén waveswith a particle simulation method.The single particle model simulation results show that when Alfvén wavesfrequency is far lower than the ion cyclotron frequency, i.e. the resonance condition isnot met, ions are heated by low-frequency Alfvén waves through the non-resonantheating. At the stage of non-resonance heating, the ions in the direction ofperpendicular and parallel to the magnetic field are heated significantly. The heatingeffect in perpendicular is more remarkable than that in parallel, and the anisotropictemperature comes into being. When considering non-resonant heating effect of twolow-frequency Alfvén waves with different initial phases, it is found that the phasedifference have certain influence on heating effect. The heating effect changesperiodically with the phase difference, and this effect can be ignored when thefrequency ratio up to2times. When the Alfvén waves amplitude meet the stochasticheating shreshold, the non-resonance heating will overlap in the phase space and ionorbit becomes chaos, which results in the stochastic heating. The final effect ofheating is only dependent on the ratio of the background magnetic field energydensity and plasma density, and has no relevance with the Alfvén waves frequencyand amplitude.On the other hand, we set up a3-D physics model of low-frequency Alfvén wavesnon-resonant heating plasma in the self-consistent field. The solution of electromagnetic field in particles simulation are strictly derived using FDTD (FiniteDifference Time Domain). We also give a specific particle simulation programprocess. The results show that the self-consistent field has a certain shield toelectromagnetic field of Alfvén wave, and can weaken the anisotropic temperature.The effect of particle acceleration in parallel direction disappears, but the total heatingeffect is unaffected. The plasmas are heated significantly by low-frequency Alfvénwaves through non-resonant interaction.