Integrators
D-LTX 133
32-channel integrator module with differential input. Each channel consists of a two-pin LEMO input and two-pin LEMO output. The circuit schematics are available here. Of each pair, the input is on top and output below, and the "positive" polarity is with the signal on the female pin of the cable connecting to the integrator (e.g therefore the male pin of the integrator jack).
The front panel has a shared momentary "integrate" button for all channels, as well as a shared TTL logic (0V/5V) BNC "integrate gate" input. The front panel also has a BNC "integrate TP" (TP = test point) which reads off of the internal integrate on/off logic. The integrator channels have a ±15V supply on both input and output.
Integrator gain differs considerably between channels, typically by only 1-2% between similar channels, but with blocks of channels covering a range from ~70 to ~70,000 with most set ~10,000.
- Integrator 1: Toroidal array, coil current Rogowski coils, plasma current Rogowski coil, top off-radial re-entrant Mirnov coils.
- Integrator 2: Lower poloidal array of re-entrant Mirnov coils
- Integrator 3: Upper poloidal array of re-entrant Mirnov coils
- Integrator 4: Shell-mounted and center-stack poloidal flux loops, diamagnetic flux loop
- Integrator 5: Shell eddy sensor array, saddle coils, bottom off-radial re-entrant Mirnov coils
A more detailed mapping of diagnostics to integrator channels can be found here.
Calibration
The updated calibration spreadsheet can be found here, including a comparison against the old calibration data.
Due to the design of the input circuitry, an unbalanced (i.e. ground-referenced) input signal will short out one of the two nominally matched RC circuits, which may lead to a less accurate calibration if the matching is imperfect. To improve the fidelity of a square wave driving signal, a DC isolation circuit has been assembled and used.
As of July 16th 2018, one channel is blocked by a LEMO connector that could not be removed from the output (i1c14), and one channel appears to be damaged (i4c30).
As of August 23th 2018, 2 of 5 D-LTX 133s (#3 and #4) are calibrated. The other three (#1, #2, and #5) are having gain values changed. Due to a shortage of 15kΩ, 0.25W resistors, 0.1W resistors were used. Since these are rated to tolerate 40V sustained, whereas the integrator circuit is only designed for 15V, this was deemed a safe compromise.
E1939
Adjustable single-channel integrator module, typically racked in sets of 6 or 12 plus one timing module.
Integrator Module
Has "Input A" and "Input B" with 3-pin LEMO connectors, as well as A and B outputs with same connectors. Toggle sets to either Integrator or Amplifier mode, and knob sets integrator timescale ("INT-tc (ms)": 10, 5, 2, 1, 0.5, 0.2, 0.1) or amplifier gain ("AMP-gain": 1, 2, 5, 10, 20, 50, 100). Input is differential with an RC-opamp circuit on each leg. Supply is 7.5V, with a 10V output amplifier and auto-zeroing while not actively integrating.
Timing Module
Separate integration time (presumably length of integrating period) labeled for modules 1-6 and 7-12 set with 3-digit thumb wheel switch (in seconds). Activated by start/stop toggle switch and "trig" input on 3-pin LEMO. NB: As of Oct. 4th 2018, it is not entirely clear how these devices are properly triggered, although it appears to require a high-voltage (~50-100V) input signal.
3-pin LEMO pinout
Facing the front of the module, based on an existing triggering cable from a BNC source, it would appear that the "top" pin (red dot) is the shield pin, the "right" pin (clockwise from the shield pin) is signal -, and the "left" pin (counterclockwise from the shield pin) is signal +.
