Always ensure that the BEAM STOP is in place before activating any X-ray measurement with a transparent sample. This beam stop prevents direct exposure of the Image Plate by the primary X-ray, which over time will damage the image plate.
The Rigaku DMAX/Rapid is generally left ON and ready to use. If the Rigaku system is Powered Down, the Tube Voltage is set at 20 kV and the Tube Current at or between 2 and 10 mA. If the tube is relatively new, you must warm it up slowly, called Aging the Tube. If you have been told the tube has been aged adequately, you can skip the following section.
It is a good idea to check the operation of the chilled water supply system, which cools the X-ray tube. Without water pressure or at high temperature, the X-ray generator system will shut down and not be able to restarted. Nevertheless, check the temperature of the cooling water by looking at the recording High/Low thermometer on the wall behind the Goniometer cabinet (Figure 5). The temperature should be between 68° and 72°F, but the high and low values are recorded. Please advise George Harlow if you see that there have been excursions beyond these values.
Figure 5 Recording thermometer
AGING THE X-RAY TUBE
Aging the X-Ray tube is a slow build up of power to the tube, up to its Operating Power. To accomplish this, first, increase slowly, the tube voltage from 20 kV, up to 46 kV. Do this by pushing the UP button repeatedly marked kV on the Control Panel. Slowly increase up to 46 kV. Alternatively, you can let the RINT Control do this automatically upon commencing X-ray exposure. See Figure.
Follow this by increasing the tube current to 10 mA from the power down setting of between 2 kV and 10kV. Let the Rigaku System dwell at these two settings for about ten minutes.
The next step in aging the tube is to increase the tube current to 20 mA. Let the system dwell here for an additional ten minutes. This is the slow, aging process.
After aging the tube at 20 mA, increase the tube current now to 30 mA for another ten minutes. At the end of this time, increase the tube current to 40 mA. This is the maximum mA for tube current.