2012-09-10 

Arrive 09:40

The interface program left running on 2012-09-07 had crashed at 08:39 on 2012-09-08
This was due to an error in the "process_digits.py" script, which failed to recognise a '0', and caused the program to hang.
I had intended the script to retry if it failed to get a digit, but forgot to remove older code that paused the program and showed the digit to the user.
I have now removed the older section of code. Hopefully if the problem occurs again, the "process_digits.py" script will fail.
"get_pressure.sh" should then take a new photo and try again.

Prepared plots of gun focusing done on 2012-09-07 for Sergey.

File names (under each directory in focus, deflection, accel, venault)
i-v_curves.png - Show all the I-V curves taken varying that electrode
tcs.png - Show the TCS (derivative) of the I-V curves
i-v_max.png - Show maximum I for each electrode setting, and V at which it occurs
tcs_max.png - Show maximum TCS for each electrode setting
tcs_max_position.png - Show position of maximum TCS for each electrode setting

In some cases, also plotted the closest to optimum curves, since there are quite a lot.

Also plot comparison between curves at 11am and 4pm - NOTE: NOT AT OPTIMUM POTENTIALS

And comparison between first curve at optimum potentials on 2012-09-07 and last curve taken before crash on 2012-09-08
"compare_2012-09-07_vs_2012-09-08.png" saved in folder "2012-09-07", symlink in this folder

Noted significant difference, not just in maximum value, but in shape of curve...
Compare TCS as well.

Talked to Sergey
 - Parameters aren't necessarily optimum (I know this), best way to optimise is with a cyclical adjustment (I did one cycle only)
 - Not much I can do to optimise further, due to time dependence of curves, and long time taken to do a single cycle

Plan:

- Take control measurements of current sample
- Evaporate Au at e-8 mbar for 30min
- Take more measurements, compare
- TURN OFF FILAMENT, turn off turbopump, fill chamber with He gas 
- Prepare Black Au (on top of shiny Au) at e-2 mbar for 30min
- Pump down chamber to e-6 mbar
- Take measurements of Black Au 
- Compare Black to Shiny Au


Control Measurements
Curves do not resemble curves from 2012-09-07 - slope is far from constant in plateau
- Electrode potentials (Va, Vf, Vd) have changed slightly!
- Reset to optimum values, try again
Va = 126.7V (from 128.8)
Vd = 2.50V (from 2.48)
Vf = -5.50V (from -5.48)
Vv = 23.2V (unchanged)

Shape still looks wierd; extra maxima/minima in derivative.

Manually adjust.
Try:
Va - 126.8V
Vd = 2.69V
Vf = -6.00V
Vv = 23.2V

Still looks wrong, as good as I am going to get.
I hate this experiment.

Record pressure whilst evaporating.