(Mounted on 2 /4" UHV Flange)

The Model 2 Ultrasoft X-ray Source illustrated above was developed for use in the radiometric calibration of grazing incidence spectrometers, and its design features have made it useful in other applications as well. A special feature is that two equivalent output beams are provided, from two views of the single emitting spot where the electron beam from the hairpin filament collides with the replaceable anode cap. This spot is between 0.2 and 2 mm in diameter, depending on the voltage and current. The centerlines of the two output beams lie in a plane containing the e- beam, which is along the axis of the source, and they are at equal angles of 45° to the beam (or 60° as a special). Since the e beam is along a normal to the anode surface symmetry requires that the two output beams be of equal radiant intensity, and indeed this has proven to be the case within about 2% at Mg-K, O-K, C-K, B-K, and Be- K. This accuracy in beam ratio measurement was achieved by repeated measurements in which the apertures and detectors were interchanged to reduce systematic errors. The source output within each of these five bands reached more than 1011 photons s-1 sr-1 at the maximum anode loading of 5 watts, and was 1012 photons s-1 sr-1 for the C-K band at 4.2 watts. This geometry is intended to allow monitoring of one beam by our absolute photon counter while the other beam is used to calibrate the instrument or provide a known flux for some other purpose.

The source mounts on a tapped rotatable 2-3/4" UHV flange on the customer's vacuum system, and is bakeable to 350°C. Spare filament assemblies and anode caps are included, as is our Model 3B X-ray Source Control which provides a cathode heating supply, self-bias beam control, metering of the heating current and beam emission current, and cabling, mounted on a 19" x 8-3/4" panel for rack-mounting. A 12' HV cable with connector mating that on the source is provided, to the other end of which the customer will attach the connector which mates to his HV supply. A regulated and filtered l0 KV supply such as the Bertan Model 205B-1OR is recommended.

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Austin Instruments, Inc.
10 Temple Street Reading MA 01867-2830
Tel: (800) 818-7403 Fax: (800) 818-7403 e-mail: