Abstract
A new type of ion source, micro gas jet (MGJ) ion source, was proposed, which can achieve high transport efficiency in the beam focusing optics system with a very small ion beam at the starting point. The MGJ ion source consists of an anode, a cathode, and an extractor. The anode has a micro aperture as a material gas inlet, and separates between a high pressure and a high vacuum areas. The material gas jet going out from the aperture is ionized by DC voltage applied between the anode and the cathode, and then extracted by an extraction voltage. We reported experimental results on the discharge phenomena in the vicinity of the micro aperture. A relationship was found between the threshold voltage for the discharge in the inhomogeneous pressure region and effective pd (where p is the pressure, d is the distance between electrodes), which was not just pd, like Pashen's law.
