Hitchhiker's Guide to the Dilution Refrigerator - Harvard University ...

have positive bias on all of your gates, and may cool down. However, if you want to give a
thorough diagnostic, it is best to first test gate leakage for each gate separately. Follow the same
procedure as above, but only put one gate to bus at a time. That is, connect the unused channel
and put it onto bus. Put ONE gate channel to bus, remove its grounding cap, and turn up the
positive bias. Record the room temperature value on the DMM. Turn down the bias again, replace
the grounding cap, and take the gate channel off bus. Repeat with all gates. Each gate should
have a room-temperature gate leakage on the order of MOhms or higher. If much lower, it's a
sign that something's wrong with your gates, your ohmics, your breakout box, or your wiring.
Once you've checked each gate individually, follow the above procedure for putting all gates onto
positive bias. The total value on the DMM should be slightly lower than the sum of individual gate
values. Now you're ready to cool.
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