The Effect Of A Weak DC Magnetic Field On Discharge Characteristic In A Radio-frequency Inductively Coupled Plasma

In recent years, inductively coupled plasma (ICP) has been widely used in laboratory and industrial research. Inductively coupled plasma source has two discharge modes:one characteristics has a low plasma density, low luminous intensity, uneven spatial distribution of plasma,called as electrostatic(E) mode; another one characteristics has a high plasma density, high luminous intensity, even spatial distribution of plasma, called as electromagnetic(H)mode. In the past, our experimental team have researched the discharge process mode transition, at the same time also studyed the discharge instability. On the basis of this work, our experimental team study on plus Helmholtz coil under the action of a direce current (dc) weak magnetic field, analysis of the radio frequency inductive coupling plasma discharge characteristics, plasma discharge characteristics of different conditions are discussed and analyzed. In drder to more clearly comprehend a direct current (dc) weak magnetic field influence the characteristics of the radio frequency inductive coupling plasma discharge.This paper,by using the teslameter, voltage prober, current probe, LeCroy digital oscilloscope, Langmuir probe and the Z-Scan measuring system, measure the Helmholtz coil dc magnetic field spatial distribution, plasma antenna voltage, plasma antenna current, plasma absorbed power and plasma dissiated power, smith chart, the forced oscillation,and a variety of parameters, research and analysis the impendance matching network, power, dc weak magnetic field, air pressure and other factors on the E and H discharge mode characteristics,mode transformation behavior,power transfer efficiency and the influence of plasma discharge characteristics. In the experiments in the first place to measure the equivalent resistance of the radio frequency (rf) antenna coil and r impedance matching network, calculate the net absorption of plasma power and power transfer efficiency. In the experiments,the concepts of positive and negative feedback regions are established basing on the influencing of stray capacitor in r impedance matching work to the output power of radio-frequency power supply. It is found that jump mode transition easily exists and many parameters including critical power of jump mode transition, width of hysteresis of jump mode transition, mode transition and a series of discharge characteristics under the action of a dc weak magnetic field obviously changes as altering impedance matching network at the same conditions when plasma discharge is in positive feedback region; In negative feedback region, its influence on plasma changes little. Research also found that the dc magnetic field is certain influence to the improvement of power transfer efficiency and diminished the forced oscillation of nonlinear evolution of rf power behavior.