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High voltage sparks may seriously damage the detector. Observe the chamber pressure
carefully every time the high voltage is turned on. Switch off the high voltage immediately
in case of a temporary pressure rise by an order of magnitude or more. This indicates
high voltage sparking.
If sparking occurs, turn down the high voltage immediately and wait some time (up to 5
min.). Check for shorts, start the “Start-Up” procedure again with and increase voltage in
small steps. Turn off the high voltage completely, stop the procedure and call SURFACE
CONCEPT for further assistance, if is it not possible to reach the operation voltage without
sparking.
• After finishing the previous steps with a satisfying result, you may now start carefully with a charged
particle or light source observing the detector output.
Turn off the high voltage, close the software and turn off the controller before performing
any changes of the cabling.
4.2 Standard Operating Procedure
Use this procedure later on for all operations when the detector has already been operated in vacuum
before and has not been vented in between.
• Connect the CEM 4230 Detector Setup as described in chapter 3.
• Be sure that the vacuum pressure at the detector is below the specified maximum operating pressure.
• Turn off all sources for electrons, ions, light or X-rays that might hit the detector.
• Turn on the power for all devices.
• Switch on any HV supply.
• If possible, watch the vacuum pressure while increasing the high voltage; turn the voltages back, if an
unusual increase is observed in the pressure (indicator for high voltage sparking).
• Increase the voltage step wise up in a couple of minutes to the operation voltage of the CEM. It is given
in the specification sheet of the detector.
• Switch on your charged particle or light source observing the detector output.
Turn off the high voltage, close the software and turn off the controller before performing
any changes of the cabling.
