Soft X-ray emissions by high-current vacuum discharges

Soft X-ray emissions by Z-pinch discharge between vacuum spark electrodes are examined. Mainly aluminum and molybdenum were utilized to generate soft X-rays, and emissions resulted for pulse currents of about 150 kA. These emissions increased as the discharge current increased. A large X-ray intensity was obtained when a spherical anode and a conical cathode were used. A stable spot plasma was produced for an electrode separation distance of 2 mm. For molybdenum, the X-ray emission of the 0.52-nm line and continuous X-rays of 0.65-1.2 nm were observed. The X-ray continuum was assumed to be a recombination continuum. For aluminum alloy containing magnesium, the 0.62-, 0.66-, 0.72-, 0.78-, and 0.92-nm lines were observed. The experimental results indicate that vacuum spark is a potential exposure source for X-ray lithography