Ion current measuring was tried during the day. At the outer shell of the spherical
deflector (SD), a current about 70uA was observed with electron beam on, and
0 uA without the beam, regardless of the adjustment of the voltages which can
steer the ion beam.
Attempts to measure the ioncurrent from the plates of Wien Filter and Faraday Cup
were also failed. Couldn't see any change at the nA meter when changing the HV's
which should steer the ion beam if it exists.
After 10:00pm, attempt to monitor the current from the split lense just before the
Spherical Deflector was made. Without gas in the cell, druing electron beam filling,
the current varied from 20 uA to 100uA ( with HV setting at 2.5 kV ). Then these two
channels were destroyed ---- the HV outputs could not stay at the setting point;
one dropped to about 2.4kV, another dropped below 1kV, and very unstalble.
Suggestion:
1. LOwer down the hv setting of these lenses and SD which can see the electron
beam directly during the filling;
2. Or use other HV supplies, eg. EG&G, which can source / sink more current.
Yuan
This archive was generated by hypermail 2.1.2 : Mon Feb 24 2014 - 14:07:29 EST