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PEM (Center)
tatsuki.washimi - 18:31 Monday 10 March 2025 (32939) Print this report
Test of the Large Coil Amplifier 

[Federico (remote), Irene, Washimi]

We connected the amplifier (KEPCO BOP72-6D) to the Large Coil for magnetic injection, and also the KAGRA ADC channels.
The channel names are:

  • K1:PEM-EXCITATION_IY0_RACK_1_EXC  : DAC output [counts]
  • K1:PEM-PORTABLE_IYC_RACK_IY0_ADC0_DSUB5_OUT_DQ  : Amplifire input voltage [V]
  • K1:PEM-PORTABLE_IYC_RACK_IY0_ADC0_DSUB6_OUT_DQ  : Amplifier output voltage monitoring [V]
  • K1:PEM-PORTABLE_IYC_RACK_IY0_ADC0_DSUB7_OUT_DQ  : Amplifier output current monitoring [A]
  • K1:PEM-PORTABLE_IYC_RACK_IY0_ADC0_DSUB8_OUT_DQ  : Magnetometer at the center of the coil [pT]

 

We measured the calibration factors between the monitoring ports (V_mon, I_mon) and the applied voltage and current on the coil (displayed on the front panel) by operating the amplifier in a DC power supplier mode.
Now the calibration factors are applied to each channel on the MEDM.

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Comments to this report:
tatsuki.washimi - 20:13 Monday 10 March 2025 (32941) Print this report

I measured the transfer functions:

  • Fig.2: DAC output -> Amp V_in, V_out, I_out
  • Fig.3: Amp V_in -> Amp V_out -> Amp I_out -> Magnetic Field @ Coil Center
  • Fig.4: Magnetic Field @ Coil Center -> Magnetic Field @ BS Magnetometer X/Y/Z

During this test, the excitation amplitude was 20 counts, and the height of the BS Magnetometer ASD was about 1e2~1e3 pT/√Hz << about 1e4pT/√Hz @60Hz(w/o injection).

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tatsuki.washimi - 9:04 Tuesday 11 March 2025 (32948) Print this report

I compared the measured transfer function of V_moin -> I_mon with a theoretical expectation, I/V = 1/(R + iωL), where  R = 8.5 Ω and L = 116 mH (klog32420).

The result was not consistent. Is it due to the input/output impedance of the amplifier and ADC?

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tatsuki.washimi - 19:23 Tuesday 11 March 2025 (32963) Print this report

[Irene, YokzaWashimi]

Today we changed the power supplier for the temporal magnetometer from the portable one (PSU1) to KAGRA's whitening filter.

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