We present a Penning discharge as a possible radiometric transfer standard source in the vacuum UV, primarily in the spectral region below 20 nm. Following the concept of Finley et al., we have designed a Penning source using NdFeB permanent magnets. Emphasis was put on simple operation, quick electrode exchangeability, and easy source readjustment. The radiant intensities of the emission lines from different ionization stages of both buffer gas atoms and atoms sputtered from the cathodes have been studied in various discharge conditions. For selected Al and buffer gas emission lines we determined the absolute radiant intensities by a comparison with the calculable spectral radiant power of the Berlin Electron Storage Ring. A comparison with data from our hollow-cathode transfer standard source is given.
If a permanent magnet has both a homogeneous polarization inside the material and a linear demagnetization characteristic in external fields, its magnetic field can be expressed using a surface pole model. For magnets satisfying these conditions and, in addition, having a rectangular shape, the fields at any given-point in space can be calculated analytically. An algorithm for this calculation is presented in a form that can easily be implemented into a computer program. In our experiments we used Nd,Fe,,B magnets to support low pressure glow discharges by magnetic fields. The magnets can be seen as composed of elementary magnets with rectangular shape, for which the magnetic field distribution is calculable. We present results of field calculations for various configurations of permanent magnets that we used in hollow cathode and Penning discharges.
A Monte Carlo simulation code is described that is suitable for modelling low-pressure glow discharges that possess cylindricaLsymmetry, but are of otherwise completely variable geometry. In this single-particle simulation in 3 space and 3 velocity dimensions, an entire discharge including the cathode fall can be modelled with or without magnetic fields of arbitrary shape. Electric and magnetic fields are given externally and are not adjusted self-consistently. Collision processes are modelled in great detail, and cathode sputtering phenomena are also included in the simulation.This simulation code is applied to hollow cathode discharges with and without superimposed magnetic fields and to a Penning discharge. Exemplary results are shown that include density profiles of cathodesputtered atoms, energy distribution functions of electrons and cathode sputtering effects for a Penning discharge. Comparisons to results from experiment and other simulations are given.
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