Coil current monitors
Currents in the equilibrium field coils are measured by Rogowski coils wrapped around the field coil leads at various points in the LTX test cell (L210/211), mostly near the Hoffman boxes, and also be integrated current sensors built into the power supplies.
Acquisition
Main Rogowski Coils
The coil current Rogowskis are commercial parts purchased from Rocoil, and are documented as having an instrument gain of 1.07x10-7 V/A.
Calibration testing in Jan. 2019 found that this nominal gain is generally accurate. Most Rogowskis that were tested fell within ~1% of the nominal gain. The largest deviation measured was the Internal coil Rogowski, which appeared to have a 5% higher gain when measured with a second wire run through the Rogowski next to the main coil lead. The 5% difference was deemed small enough to not bother conducting further experiments to test whether they persisted when driving current through the main coil lead itself.
| Coil | Rogowski | Integrator | Digitizer | |||||
|---|---|---|---|---|---|---|---|---|
| Location | Wrappings | Gain (Vs/A) | Chassis | Channel | Gain (1/s) | Chassis | Channel | |
| TF | On red lead at TF terminal plate | 3 | 1.07e-7 | 1 | 30 | 505.5 | Neos | 90 |
| OH | On OH bus above NBI | 1 | 1.07e-7 | 1 | 29 | 500.9 | Neos | 88 |
| Blue | at Hoffman box | 3 | 1.07e-7 | 1 | 13 | 1448 | Neos | 81 |
| Red | at Hoffman box | 2 | 1.07e-7 | 1 | 14 | 2952(?) | Neos | 82 |
| Orange (top) | at Hoffman box | 3 | 1.07e-7 | 1 | 12 | 4844 | Neos | 84 |
| Orange (bottom) | at Hoffman box | 4 | 1.07e-7 | 1 | 15 | 2287 | Neos | 85 |
| Yellow | Inside yellow cap bank rack | 1 | 1.07e-7 | 1 | 32 | 503.4 | Neos | 83 |
| Green | above green cap bank rack | 4 | 1.07e-7 | 1 | 31 | 2289 | Neos | 87 |
| Internal | at Hoffman box | 3 | 1.07e-7 | 1 | 16 | 2887 | Neos | 86 |
Extra/Undocumented Rogowski Coils
| Name | Rogowski | Integrator | Digitizer | |||||
|---|---|---|---|---|---|---|---|---|
| Location | Wrappings | Gain (Vs/A) | Chassis | Channel | Gain (1/s) | Chassis | Channel | |
| "OH rog" | ? | ? | ? | ? | ? | ? | Neos | 89 |
| "Yellow current" | ? | ? | ? | ? | ? | ? | Neos | 80 |
| "Green current" | ? | ? | ? | ? | ? | ? | Neos | 79 |
Power Supply Monitors
- Blue: Power supply T1 is recorded in Helios input 44.
- Internal: Power supply T2 is recorded in Helios input 45.
- Orange (T + B): Power supply T3 is recorded in Helios input 46.
- Green: Power supply T4 is recorded in Helios input 47.
- Red: Power supply DF is recorded in Helios input 64.
- TF: Power supply IF is recorded in Helios input 48.
Related Pages
Equilibrium field coils - lists parameters of the eight field coils Coil current monitor testing - brief calibration experiments to verify the coil current monitors' accuracy
Diagnostics
Magnetics (Local): Reentrant array | Toroidal array | Saddle coils | Shell eddy sensors
Magnetics (Areal): Poloidal flux loops | Loop voltage | Diamagnetic loop | IP Rogowski
Spectroscopy: Thomson scattering | ChERS | X-ray spectroscopy | Spectrometry | Vacuum UV spectroscopy
Microwaves: Reflectometry | Interferometry
Physical Probes: HFS edge probes | LFS SOL probes | RFEA
Operational Diagnostics: Ion gauges | Coil current monitors | Thermocouples | RTDs
