The Model 634 is a continuous Penning discharge source for use in many laboratory applications. Unlike a standard gas discharge source the Model 634 utilizes an intense magnetic field to confine electrons emitted by the cathode allowing higher electron energies to be achieved. These higher electron energies excite emission lines in the soft X-ray region of the source gas and the ionized material sputtered from the cathode.
Source operation is simple, it requires a supply of cooling water, a supply of non-hazardous gas (He, Ne, A, etc.) and a high voltage supply suitable for providing at least 0.5 Angstroms at 2000 V. Aluminum and magnesium cathodes are provided with the source, and replacements or alternate materials are available. Three inch quick connect flanges provided for attachment to the customers instrument or vacuum system. The pressure in the source is about 20 microns when first lit, operating pressure is typically 10-4 to 10-5 torr.
A 150 liter per second pump is adequate to maintain operating pressure. When necessary isolation of downstream components such as spectrometers or detectors can be provided by thin film filters, low conductance apertures or differential pumping.
With a limited number of cathode materials and gases this source provides nearly forty usable lines between 50 and 300 Angstroms. These are available by using single gas-cathode combinations. The source is quiet, continuous, and stable over most of the cathode lifetime. It is well suited to calibration of photon counting systems. Although the cathodes eventually fail because of the erosion caused by sputtering, their longevity is sufficient for even long calibration runs.
