Neutral bremsstrahlung measurement in an atmospheric-pressure radio frequency discharge

Neutral bremsstrahlung emission spectrum is measured in an atmospheric-pres sure radio frequency (rf) capacitive discharge for a gas mixture of helium (99.5%) and oxygen (0.5%) using a high resolution triple monochromator betw een 450 and 1000 nm. Good agreement is obtained for spectral variation and absolute intensity between the observed neutral bremsstrahlung and theoreti cal emissivity calculated using electron-neutral momentum cross sections. B ased on a theoretical fitting, the discharge is characterized by a time ave raged electron density of 2.9x10(11) cm(-3) and an electron temperature of 1.9 eV for an input power density of 28 W/cm(3). (C) 2000 American Institut e of Physics. [S1070-664X(00)03808-8].