A method to decrease the igniting power of microwave microplasma through adding magnetic field is proposed to further miniaturize low-power microwave micro-plasma source. Simulation on a planar microstrip tapered spiral antenna at 2.45 GHz is performed to obtain the optimal structure. Values of S parameters are measured through applying the ring magnets of 360
990 and 2 840 Gs on the spiral antenna. Finally
the excitation effects of low-power microwave micro-plasma are investigated by changing the magnetic field strength and the magnetic orientation. Experimental results show that both the igniting and the extinguishing of microwave microplasma changes with the changes in the strength and the orientation of the added magnetic fields at the air pressure of 666.6 Pa. The S-pole outward of the ring magnet motivates to ignite microwave micro-plasma more easily
and the igniting power decreases as the strength of added magnetic field increases. A comparison with the igniting power without adding magnetic field shows that the minimum igniting power with adding magnetic field reduces about 15%. It can be concluded that the proposed method has potential applications in the fields of micro-chemical-analysis system and surface processing of small-scale materials.
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