Next Meeting

Date: 3 Jun 99

Time: 1500-1600

Place: FEL Facility Break Room

Agenda for Next Meeting

• Plans for gun rebuild and processing (Siggins, 15 min)
• Status of apertured cesiator (Biallas, 15 min)
• Status of ion implantation (Biallas, Siggins, 15 min)

This Week's Attendees

G. Biallas, C. Bohn, K. Jordan, T. Siggins, C. Sinclair

Discussion

We rehashed the arguments leading to the decision to replace the cathode ball in June. The result will, in effect, be a "new gun" for which the experience with the present gun probably will not apply, at least not in detail. The goal is to assemble the new gun in the first half of June, then bake and process it during the last half of June, and in early July if need be. For the record, we will be working to turn on beam in the FEL on Monday, 12 July.

One resource who will not be readily available is D. Bullard. W. Oren asked for his time to aid in reworking the YRs for CEBAF, and C. Bohn concurred. At some level, this sets us back. The priorities are clearly (1) replace the cathode ball with the spare and bring the gun back up to voltage, (2) finish and install the apertured cesiator, and (3) prepare and do the ion-implantation studies. Presently it is unclear whether the cesiator can be finished, tested, and installed without seriously impacting the mid-July turn-on. If it cannot be completed in time, we will install it during the next gun turn-around, e.g., the next time the wafer needs to be replaced.

Progress on the apertured cesiator continues to be slow and steady. Not all the detail drawings are complete, but work is being funneled to the Machine Shop as the drawings come out. The earliest the cesiator would be ready for testing is ~15 June. Much discussion about testing and alignment methodology ensued. C. Sinclair pointed out that measuring the cesium flow requires single-monolayer detection, corresponding to about a 10 Hz frequency shift. He has a test chamber and detector with that capability and is unsure if L. Phillips has the detector. Alignment of the holes forming the cesium "channel" with respect to each other and to the cathode wafer can probably be done with a light source and without need of the Alignment Group.

Polishing of the ball-steel plates needed for the ion-implantation studies is also proceeding slowly, inhibited in part by steps left on the plates as a relic of their manufacturing by an external vendor. Bullard is finding that "stuff comes up" with each progression to a finer grit. It is not known why. T. Siggins has started polishing one of the plates himself to see if it is a matter of technique. At present, the outcome is uncertain. Sinclair pointed out that trying titanium plates would be of interest and recommends we do so once funding is available (~1 k$ for a "chunk" of Ti, plus manufacturing costs).

Closed Action Items

• Siggins: Inspect the polished ball-steel plates and, if necessary, advise D. Bullard how to improve the polishing. Status: Siggins is now polishing a plate himself to see what specifically is involved.

New Action Items

None.

Old Action Items

• Sinclair: Prepare procurement package for DLC-coated samples for Dylla's signature. Status: Biallas needs to provide Sinclair with a drawing of the electrode plates.. (due 20 May 99)
• Siggins/Biallas: Specify design of experiment to measure cathode temperature. (due date TBD)