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Electronics System I & II. Electronics System I & II. Overview. Electronics System I & II. Overview (Cont’d). Electronics System I & II. System I Chose one spot and apply some breakdowns to clean the surface. All paths that have nothing to do with FE are physically disconnected:
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Electronics System I & II Breakdown 28th September 2010 R. Santiago Kern
Electronics System I & II • Overview Breakdown 28th September 2010 R. Santiago Kern
Electronics System I & II • Overview (Cont’d) Breakdown 28th September 2010 R. Santiago Kern
Electronics System I & II • System I • Chose one spot and apply some breakdowns to clean the surface. • All paths that have nothing to do with FE are physically disconnected: • switches S1, S2 & S6 • Overshoot capacitor C2 • Apply a defined voltage V for several runs: • Apply V (wait 1sec for current to stabilize) • Read FE current after 1sec (Keithley 617) • Read FE current after 60 secs • Turn off V (for 15 secs) Breakdown 28th September 2010 R. Santiago Kern
Electronics System I & II • High periodicity not observed • First FE current values higher than the trend • FE current increases according to applied voltage • FE currents after 60secs are all in the pA range • System I (cont’d) Breakdown 28th September 2010 R. Santiago Kern
Electronics System I & II • System II • Chose one spot and apply some breakdowns to clean the surface. • All paths that have nothing to do with FE are physically disconnected: • switches S1, S2 & S6 • Overshoot capacitor C2 • Apply a defined voltage V for several runs: • Apply V (wait 1sec for current to stabilize) • Read FE current after 1sec (Keithley 6517A or 617) • Read FE current after 60 secs • Turn off V (for 15 secs or 10min) Breakdown 28th September 2010 R. Santiago Kern
Electronics System I & II • System II (cont’d) • Keithley 6517A • Highly periodic behaviour: Keithley? • Usually first FE current values do not follow the normal trend • High stdev • FE current response depends on what has been applied before (see 1000V) Measured same day Measured different day Breakdown 28th September 2010 R. Santiago Kern
Electronics System I & II • System II (cont’d) • Keithley 6517A • FE currents after 60sec stay in the pA, except for 1000V, which reads ~10-7 A: the applied voltage has an effect in: • Surface? • Cables? (check with switching off voltage for 10min) Breakdown 28th September 2010 R. Santiago Kern
Electronics System I & II • System II (cont’d) • Comparison K6517A & K617 • K617 does not show such a strong periodic behaviour Breakdown 28th September 2010 R. Santiago Kern
Electronics System I & II • System II (cont’d) • Comparison K6517A & K617 Breakdown 28th September 2010 R. Santiago Kern
Electronics System I & II • System II (cont’d) • 10min for power off (at 700V) Breakdown 28th September 2010 R. Santiago Kern
Electronics System I & II • System II (cont’d) • HV Box out • Anode connected to FUG, cathode to Keithley • mm gap Breakdown 28th September 2010 R. Santiago Kern
Electronics System I & II • HV Box back into place • C2 out • System II (cont’d) Breakdown 28th September 2010 R. Santiago Kern
Electronics System I & II • HV Box back into place • C2 out • System II (cont’d) • Comparison K6517A & K617 Breakdown 28th September 2010 R. Santiago Kern
Ambiguous results of β-measurements due to error in gap size Black line: Exp. data Blue line: Fit to experiment Red line: β=50, d=13.5µm Breakdown 28th September 2010 R. Santiago Kern