Issues related to the Vector Fridge at the moment
Sorb Temp readout on Ch0
Ch0 may not be accurate...
Even after the sorb heater is turned on and set to 35-40mA, the temperature on Ch0 does not go up as it should...but stays at ~4K.
We know the sorb heater is working because the IVC pressure goes up when the heater current is turned on.
Also, probing the Fischer shows that the Resistor is working.
The cryostat is not isolated from the gas cabinet as its supposed to be...
- Plugging in the 7-pin Fischer for the heaters grounds the cryostat
- The Big Fridge line is not isolated fully from the cabinet, and the rubber insulation is actually 500 Ohms
- The cabinet is also being grounded through the USB connection to the AVS47 computer interface (as well as being grounded through its own mains connection)
With the current probe design, vibrations from the room are picked up by the probe.
This could cause problems if the sample is moving within the field
Also, the sample may be picking up electrical noise due to vibrations which show up in sensitive measurements. eg. random jumps in resistance in SdH
- When sweeping the magnet, the shunt resistor has to be measured as well to get an accurate value of the field around
- Hysteresis problems!
- When condensing mixture, the program automatically turns the mixture compressor off as soon as the dump is empty without giving the fridge time to stabilise, so it crashes unless the compressor is manually turned back on quickly.
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