Procedure for using the Thermal Evaporator (carbon-rods).
Note: Several of the lights on the front panel are burned out, however the switches still work (up = on).
1. Behind the evaporator, check the water chiller to be sure that the water flows to the evaporator is on (gauge on the right- the float should be at approximately 14-20). This is almost always on, and therefore should only be checked (for potential problems).
2. On the evaporator, be sure that the following conditions are met (all of the following are on the left side of the evaporator):
Manifold - closed
Main Valve - closed
Pump Air inlet – closed (down)
Bell Jar Air Inlet – closed (down)
3. On the front panel, turn on the Main switch (light is broken but the switch reads ON).
4. On the front panel, turn on the Mechanical Pump (light is broken but the switch reads ON).
5. On the left side of the evaporator, move the arm for the Manifold Valve to Backing Open.
6. Turn on the Diffusion Pump (front panel).
7. Wait about 20 minutes for the diffusion pump to warm up. Adding liquid nitrogen at this time may help to reduce pump down time. During this time you can proceed with Steps 8 through 12.
8. Sharpen an electrode (they can be sharpened using the electrode sharpener located above the pencil sharpener in the main laboratory).
9. Install the sharpened carbon electrode You will need a flat-head screwdriver for this. Be sure that the tip of the electrode is flush against the C block, AND that the spring on the electrode is compressed (so that when the tip is evaporated, it stays in contact with the C-block)
10. Place your samples on the coating surface (round disk-holds 4 thin sections or ~6 1” round epoxy mounts)
11. Place the bell jar over the apparatus (be sure to place it symmetrically about the seal to ensure that the vertical posts do not pierce the jar). The jar is heavy, and lifting it can be awkward. If you are unsure of the best way to do this, ask).
12. Place the black screen/shield over the bell jar.
13. If you have waited 20 minutes since step 7, move the Manifold Valve to Roughing Open.
14. On the front panel, turn the Discharge Gauge on (to position 1). It could take up for a minute for the vacuum gauge to read properly.
15. When the pressure drops below 100 milltorr (takes about 3 minutes), move the Manifold Valve to Backing Open, and the Main Valve to Open (in rapid succession). Note that there are two scales on the gauge: the needle starts on the left, then moves to the right post, and then back to the left (as the vacuum gets better).
16. When the pressure drops below 0.1 millitorr, turn the Filament Heater on.
17. Increase the Autotransformer slowly (by turning it clockwise) until material begins to evaporate (be sure not to look directly at the electrode as it turns to orange).
18. When the material has evaporated, rotate the Autotransformer counter-clockwise (until it stops).
19. Turn the Filament Heater off (it may have turned off during the analysis).
20. Turn the Discharge Gauge off.
21. On the left side of the evaporator, turn the arm on the Main Valve to Closed.
22. Open the bell jar air inlet (left side). When the hissing stops, remove the cage.
23. Remove the bell jar (being sure not to push it into the posts).
24. Close the bell jar air inlet (black toggle should be down).
25. Remove Samples.
If you want to coat additional samples, return to step 8. If not, continue to step 26.
26. Turn the Diffusion Pump off.
27. Wait 30 minutes while the diffusion pump cools.
28. Move the Manifold Valve to the Closed position.
29. Turn off the Mechanical Pump and Immediately Open the Pump Air inlet.
30. Turn the Main Switch off.
31. Close Pump Air Inlet.