A Novel Metastable Atom Source Based on DC Glow Discharge Pinch

详细

− Metastable atoms of noble gases have many applications in scientific research and industrial application. Though previously many such development of metastable atom sources are reported, in our endeavor for development of a source of this kind, we could develop a novel, simple structure, maintenance free glow discharge source that could produce metastable atoms of noble gases. This source is devised with two cathodes and a cylindrical anode paired with one permanent magnet. The electric field in between cathodes and the anode coupled with the magnetic field produce glow discharge in the centre of the source. The device was tested for various combination of anode voltage and filled helium pressure. The anode voltage was varied from 300 to 2000 V where as the filled pressure was varied from 450 mTorr to 1 Torr. The plasma extends to the outside of the source volume through the aperture in one of the cathode in form of a pinched glow. Due to this pinch, energetic electrons are generated and they excite the neutral atoms in their vicinity. The spectral lines of the glow discharge were observed by one optical spectrometer. Metastable helium atoms were observed at their transition wavelengths of 388.8 and 501.6 nm. The detail designing of the source and experimental results are reported in this article.