Showing papers by "Tilmann D. Märk published in 1978"

Cross Section Ratios for the Electron Impact Production of Singly and Multiply Ionized Rare Gas Ions

Abstract: Electron impact ionization of He, Ne, Ar, Kr and Xe has been studied with a double focussing mass spectrometer Varian MAT CH5. Ratios of various multiple ionization cross sections with respect to single ionization cross sections for He, Ne, Ar, Kr and Xe at electron energies of 50, 100 and 150eV are given. These cross section ratios are compared with previous determinations.

Some investigations of the ignition and development of breakdown in cylindrical hollow cathode glow discharges

Abstract: The breakdown behaviour of a hollow cathode glow discharge is investigated in a cylindrical, hollow cathode structure having an internal diameter of 2 cm. The anode is a plane electrode across one end of the cathode cylinder. Pressures of argon between 20 and 107 Pa were used (0.15 to 0.80 torr), and applied voltages between 800 and 2500 V. It is shown that the statistical time lag for breakdown is in the range of ∼ 1 ms and depends on the applied voltage, the gas pressure, and the history of operation of the discharge tube. The rise time of the discharge current ranges from about 10 ns at high pressure and voltage to about 200 ns at the lowest pressure and voltage used. The discharge propagates along the cathode axis at a speed of about 108 cm s−1. From the obtained data, a qualitative model of the first stage of the discharge is derived. Based on this model, a simple calculation gives values of Townsend modified first coefficient η at high values of E/N, 104 < E/N < 8 · 104 Td which fit well at the lowest E/N, where they approach the data of PENNING and KRUITHOF in argon. In contrast to the extremely short initial current-rise times, in the submicrosecond range, the discharge currents reach steady-state values only after about 300 μs.