Electrical Asymmetry Effect In Inhomogeneously Magnetized Capacitively Coupled Plasmas

The electrical asymmetry effect combined with the magnetic asymmetry effect in a geometrically symmetric argon discharge is investigated using a one-dimensional particle-in-cell simulation with a Monte Carlo collision model. Both the asymmetry effects can induce an asymmetric plasma response with a consequent dc self-bias. It is found that these two asymmetry effects work independently of each other to some extent, which greatly enhances the flexibility for controlling the ion properties of interest, e.g. ion flux Gamma(i) and mean ion energy < E-i > at electrodes on the weak magnetic field side. On one hand, Gamma(i) can be modulated by tuning the gradient of the magnetic field, while the angle distribution on electrodes remains approximately unaffected for a fixed phase angle theta on the weak magnetic field side with a small shift in ion energy peak. On the other hand, < E-i > can be modulated by adjusting theta, while Gamma(i) only slightly fluctuates at a fixed gradient of magnetic field. Besides, the confinement effect of magnetic field on electron motion induces enhanced ionization rate and plasma density near the sheath edge on the strong magnetic field side.