25 04 2010

Last night I controlled the fusor from LabView. I put together a simplified version of Andrew Seltzman’s Marc III controller. So far I can:

  • graph the chamber pressure in realtime
  • enable/disable fuel
  • set the fuel flow in SCCM
  • see actual fuel flow rate from mass flow controller
  • enable/ disable high voltage
  • set frequency and duty cycle for high voltage

The HV duty cycle lets us do fusion trials without melting the grid.

Something I’ve noticed: when the plasma becomes unstable and sparks… it crashes the data acquisition card. I’m guessing the sparks are creating powerful EMFs. We may need shielding.



3 responses

25 04 2010
Raymond Rogers

You undoubtedly need protection diodes on the inputs if you have arcs.
Having said that:
You should trace/visualize how far off ground your computer is with respect to anything the wiring is close too. Remember the grounding system has inductance and therefore impedance to fast high current disturbances.
Aside from generically putting in protection circuitry you should experiment ( I am presuming “crashing” means recoverable) by disconnecting the acquisition card and then reconnecting wire by wire; or circuit by circuit, the point is to find the problems.
I have no idea how hard it is, or dangerous, to reproduce the arcing though.
I also recommend putting aside the physics and doing this now. Control and knowledge of your instrumentation will undoubtedly make your like easier later.

25 04 2010

can you send me a schematic showing where you put the protection diodes? I have my guesses, but nothing is as clear as a schematic.

6 06 2010
QUADRUPLE BUBBLE!!!! « Prometheus Fusion Perfection

[…] we were having problems with transient voltages spikes or EMFs crashing the data acquisition (DAQ) card. Today was a big test for the new transient […]

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