Vi = 1.86V
Is = 0.232e-8A
-Now going to adjust deflection and record sweep, for fixed other electrodes. Results in folder "deflection".
+Now going to adjust deflection and record swee, for fixed other electrodes. Results in folder "deflection".
+
+Data suggests Vd = 2.00V is actually better than Vd = 2.38V
+Vd = 2.50V is the best.
+
+Now adjust focus electrode for Vd = 2.50V. Results in folder "focus".
+Results suggest Vf = -5.50V is the best.
+
+Now adjust accelerating electrode. Results in folder "accel".
+Results show that Va = 126.7 is probably the best, although some uncertainty in last digit.
+
+Now adjust venault voltage. Results in folder "venault". Results show Vv = 23.2 is the best. Changing venault alters height of curve, but does not significantly affect position or width.
+
+Noted that shape of curve at optimum values seems to have changed. Restore all values to originally quoted above. Compare with first data files. Results in "reset" folder.
+
+Yes, they did change. Even when normalised. The derivatives appear very similar though.
+
+Didn't notice any "overshooting" today. Maybe because I increased Va from ~40V to ~130V. If Va is too small, electrons reflected off the sample might not be recollected on the accelerating electrode => space charge effect (gas near sample becomes charged, affects potential seen by incoming electrons, affects current). If Va is large enough, almost all reflected electrons will be collected on the Va electrode.
+
+Going to set everything to optimum values:
+Va = 126.7V
+Vd = 2.50V
+Vf = -5.50V
+Vv = 23.2V
+
+Increase resolution of sweeps to 10 DAC steps (~0.05V). Monitor temperature (ADC0) over weekend.
+On monday, evaporate more gold onto surface, see if spectrum changes.
+Then evaporate black gold onto surface.
+
+Going home now.
+
+
+
git.ucc.asn.au / matches / honours.git / blobdiff
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