Discharge structure hierarchy of highly electronegative plasma and the implication on nuclear fusion at low pressure and quasi-cold ions approximation

Abstract

In this paper, the discharge structure of an Ar/SF6 inductively coupled plasma (ICP) at the low pressure, 10 mTorr, is investigated by the fluid simulation at the quasi-cold ions approximation, i.e., room temperature. The structure is found to be hierarchal and in this simulated hierarchy, the stratification, the parabola profile in the stratified core, the double layer, and the coagulated profile in the core center are examined. This fluid simulation version and a quasi-fluid simulation of an Ar/CF4 ICP given by the HPEM code, cooperatively enlighten the discharge structure of highly electronegative ICPs and meanwhile suggest the potential applications of them. It is found that when the ions are cold the hierarchy is predicted and when the ions are thermalized the simple discharge structure appears. In the simulated hierarchy, the double layer formed at the interface of halo and core is given by the ionic and acoustic vibrations. The simulated cations flux and potential at the two sides of the double layer are double-valued and the simulated double layer is modelled as the dipole microscopically and as the capacitor macroscopically. The evolution of discharge structure hierarchy is presented, in which the harmony among many processes in the hierarchy are achieved and the charm of self-coagulation is exhibited, i.e., the bigger is the coagulated volume, the denser is the coagulated mass. This provides insights for creating possibly the free nuclear fusion by means of self-coagulation, and this type of nuclear fusion without the inertial and magnetic constrictions is achieved by means of the compressible heating scheme. The self-coagulation helps people re-recognize the anions Boltzmann balance, and meanwhile it turns the discharging and collisional plasmas into the collisionless and astrophysical plasmas, in which the double layer and ionization instability occur.