User name Templon
Log entry time 16:15:47 on December 20,1999
Entry number 31610
keyword=cryotarg temp excursion
Beam went off and cryotarget alarms sounded. Reason: pressure too high
in loop. Reason: when beam went off, temperature dropped quickly and
HP heater came on to compensate. Time constant of heater seems to be
too small as heater overcompensates, thus pressure in cell loop goes from
about 106 psi (beam on) to 100 psi (beam off, heater not yet on) to about 115
psi (heater on at max). It just happened again during typing this message
and this time the alarm was on temperature not pressure (perhaps i misidentified
the previous error?) Temp goes up to about 7 K (setpoint 6.8 K) during event.
Don't feel confident to make change in PID parameters myself.