Microfabricated inductively coupled plasma generator

The design, fabrication, and characterization of a surface micromachined pl asma generator is described for the first time in this paper. The plasma is sustained without electrodes by inductively coupling a 450-MHz current int o a region of low-pressure gas. Both argon and air plasmas have been genera ted over a range of gas pressures from 0.1 to 10 torr (13.3-1333 Pa). Typic ally, the power used to sustain the plasma is 350 mW, although similar to 1 .5 W is required to initiate the discharge. Network analysis of the plasma generator circuit shows that over 99% of the applied RF power can be absorb ed by the device. Of this, similar to 50% is absorbed by the plasma and the remainder of the power is dissipated as ohmic heating. An argon ion curren t of up to 4.5 mA/cm(2) has been extracted from the plasma and the electron temperature is 52 000 K at 0.1 torr, This plasma source is intended for el ectronic excitation of gas samples so that the presence of impurities and t oxins may be detected using optical emission spectroscopy.