Some tests and characteristic noise of the RH drivers: https://dcc.ligo.org/LIGO-E1000785-v1
The documentation shows noise measurements of ring heater drivers over 0-1.6 kHz span, it would be nice to have have more resolution at LF.
Key points about the TCS Ring Heater Driver:
- Conversion 0.08A/V (as is, although this can be adjusted)
- ~0.07 µA/√Hz @ 100 Hz for 100 mA
- ~0.16 µA/√Hz @ 100 Hz for 600 mA
What it does show is increasing noise as the current is increased across the load. It is low compared to expected driving currents for the tank (0.6 A, for 50Ω total load) but maybe note for the shields (~24 mA for refcav shields, for 50Ω heater load).
It doesn't seem to include a characterization of the thermal sensing circuit's noise.
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Here's the RH driver PCB for aLIGO:
https://dcc.ligo.org/DocDB/0021/D1002529/006/Driver_RingHeater.pdf
It uses this power amp: https://www.digchip.com/datasheets/download_datasheet.php?id=508953&part-number=LM12CLK
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