55 lines
2.9 KiB
Markdown
55 lines
2.9 KiB
Markdown
# CPD User Guide
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## Changing the sample
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1. Stop the turbopump:
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1. Press the stop button on the control panel
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2. Close the valve between pump and chamber (on top of the turbo pump), by screwing it into the pump
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2. Ventilate the chamber
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1. Open the gate valve
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2. Carefully open the needle valve (usually less than 1/8 turn)
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3. When the chamber can be moved, close both valves again
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3. Take off the chamber
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1. Make some space to put the chamber (mind the grease on the bottom edge)
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2. Carefully lift the chamber. Good places to grab it are the tubing on the left and the right bottom edge.
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***Caution***: The tube connecting the chamber with the pump will exert a force to the right!
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**Make sure you do not crash the chamber into the sample tray!**
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4. Move the sample away from the gold mesh
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1. Move the tray fully down by turning the upper micrometer screw *counterclockwise*
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2. Move the tray fully to the left using the larger micrometer screw
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3. Loosen the screw on the clamp holding the sample in place and remove the sample
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5. Prepare the new sample
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1. Put the sample on the tray and place the clamp on it.
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2. Tighten the clamp screw (you might need to grab the nut on the bottom side)
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3. Move the tray in x-position using the large micrometer screw.
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The gold mesh should be well aligned with the sample surface
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4. Carefully move the tray up by turning the small micrometer screw *clockwise*.
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Leave about half a millimeter of space between the sample and the gold mesh
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**Do not crash the sample into the gold mesh!**
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6. Put the chamber back on
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1. Put the chamber back on and align it on the two posts on the bottom and right
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2. Check the backside to make sure that no cables are sticking out
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7. Vacuum the chamber
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1. Make sure the nitrogen venting valves are closed
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2. **Make sure the turbopump is not spinning anymore**
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3. When the turbopump has fully stopped, very slowly open the valve on top of the pump
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4. Fully open the valve **TODO: hier noch irgendwelche checks?**
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5. **Wait** until the vacuum is in the lower $10^{-2}$ range (read the value from the sensor attached to the turbopump)
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6. Only when this target pressure is reached, turn on the turbopump (control panel on top)
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7. Wait until the desired vacuum for measurement is reached (usually $10^{-5}$)
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- $10^{-4}$: **TODO**
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- $10^{-5}$: **TODO**
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- $10^{-6}$: after 1-2 days
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If the pressure does not drop enough: Use isopropanol to inspect for leaks
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## CPD Controller Calibration
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**TODO**
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This process is not always necessary.
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1. Set CPD Controller to Manual, Offset=Gold Work Function, Filter off (so you can see what happens immediately), Oscillator to ~2
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2. Move the micrometer screw close until a signal appears
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3. Set Automatic offset so that the output is 0V
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Calibration: Fresh graphite probe
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## cpdctrl-gui Software
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**TODO**
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