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4.2.2 Operation of the Detector with the MCP Front Side connected to a Reference Voltage
Follow this procedure for all later operation starts, when operating the detector with the front side of
the MCP stack connected to an external high voltage potential
• Finish the complete cabling as described in
and as described in the manual of the Single HV
Supply.
• Connect the external reference voltage to the “MCP-F” connector. DO NOT APPLY ANY HIGH VOLTAGE
yet.
• Turn on the TDC.
• Start your end-user software (e.g. GUI software) and within this software the rate meter (if available).
For details see your end-user software manual.
• Be sure, that the vacuum pressure at the detector is remarkably below 1E-6 mbar, otherwise the micro
channel plates might be damaged by a local discharging (in general: the lower the pressure, the longer
the lifetime of the MCPs).
• Turn off all sources for electrons, ions, light or X-rays that might hit the detector.
• Increase the detector voltage for “MCP-B” to the specified operation voltage stepwise within a couple
of minutes.
• Turn off all sources for electrons, ions, light or X-rays that might hit the detector.
• Now increase the external reference voltage until reaching the desired voltage for “MCP-F”. (Important:
Respect the maximum reference voltage for “MCP-F”. It is given within the specification sheet.) The
voltage increase should not exceed 400V per minute, when operating the detector with an external
high voltage applied to “MCP-F” for the first time. Otherwise turn up the high voltage carefully and
stepwise within a couple of minutes to the operation voltage.
• The voltage increase should not exceed 400V per minute, when operating the detector with an external
high voltage applied to “MCP-F” for the first time. Otherwise turn up the high voltage carefully and
stepwise within a couple of minutes to the operation voltage.
• Increase the external reference voltage until reaching the desired voltage for “MCP-F”.
• Now turn up the the high voltage carefully and stepwise within a couple of minutes to the operation
voltage. The starting operation voltage is specified in the specification sheet of the detector.
• A schematic sketch on how to ramp the voltages is given in
• 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).
High voltage sparks may seriously damage the detector anode/meander or the MCPs.
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.). Start the “Start-Up” procedure again with an increased ramp time. Turn off the high
voltage completely, stop the procedure and call your provider for further assistance, if is
it not possible to reach the operation voltage without sparking.
DLD8080 R4.30 & R4.31 Manual | Surface Concept GmbH