February 11, 2015 - CIS Group Meeting

CEBAF Startup

Laser Program

A = 50uA @ 125 MHz or 100uA @ 250 MHz

B = 499

C = 250

Laser setup

No spare amps, 4-6 weeks from IPG for two replacement amps

Replace 2m (FWHM~1mm) spot lens with 1.5m (FWHM~0.4mm) lens

Phase flip

Make divider box less sensitive to EMI?

Phase monitoring to keep phases between 3 lasers

Analog gain switching at 250 MHz

Change the laser phase

When we change the frequency use 0I04 viewer to check/set phase

Command line EPICS control sufficient now, Mike Johnson still working it

Tomas can provide a ~2ns delay cable

John can DAC control a phase delay ~2ns

To Do

We will learn at separators if we can flip A/D or D/A order

We will decide by summer time a final system configuration

GTS

Recovering High Voltage

Bubba repaired SF6 leak, pumping now and check

Test various insulators

black = bulk resistivity = shorty R28 (ordered R30, but too little resistivity so too much current draw)

white = coated with black = suffer similar resistively too low, but at least constant

white + spiral = coated with black but sand-blasted spiral (16 feet path length, so longer length of resistor)

tracking on R350 ceramic in SF6 tank possibly due to low SF6 pressure

Electrode

Nb = pressed, polished?

Steel = welded, looks good, not polished

Wave anode, but not the spider support