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Turn-On Procedures for LAPTAG Plasma Device

Page history last edited by PBworks 11 years, 11 months ago






  1. Check for argon gas in the gas cylinder. Make sure both gauges read pressure; the one closest to the bottle reflects how much gas is left, while the 2nd one reads the pressure in the gas line. The gas line pressure should read between 15 and 20 psi.


  1. Check to make sure the vacuum is good – i.e. that no leaks have developed while the machine was not in use. Make sure filament is on, and the gauge reading high vacuum is “on the 6 scale”, which means reading some number X 10-6.  If the filament is not on, check the convectron gauge (the other one) to make sure it is reading approximately 0 mT. Only if this gauge reads approximately 0 is it ok to turn on the filament. 


  1. Once the pressure is verified to be acceptably low, turn off the vacuum gauge filament. This gauge will only read up to 9x10-4, and can be damaged by higher pressures that we will be operating at.


  1. Turn water on (chiller). Make sure water is flowing – there is a flow meter in the cabinet that should read something like 1.2, and a little rotor indicator thing on the chiller that spins when water is flowing.


  1. Using the manual leak valve, set the chamber pressure to around 28-32 mT. The pressure response is exponential, so settings between 113 to about ___ will set low pressure (which can be read on the high vacuum gauge, if the filament is on), but the pressure rises very rapidly after this. Currently, a setting of ___ will give 10 mT, and ___ will give ___ mT, but since this is mechanical these numbers may change.  Also this valve has mechanical hysteresis, so the pressure resulting from a given setting on the knob will be different if the knob is being turned clockwise or counterclockwise.  Note: this leak valve has a fragile mechanism that can be bent, so should never be closed past a setting on the dial of “113”.


  1. Make sure the gate driver power supply is on (currently the Loko unit) and reads 12 Volts.


  1. Check for green light on RF unit controller circuit board, indicating it has power.


  1. Turn on big power supply (Sorensen DC power supply).  If everything is OK, the gas should break down to form plasma at a voltage setting below 100 V, or so. If the gas does not break down, expect to see a red light on the controller circuit board next to the green one, and call Pat or Walter.




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