Next Meeting

Date: 7 May 99

Time: 1500-1600

Place: FEL Facility Break Room

Agenda for Next Meeting

• Status of shield design (Phillips/Biallas, 10 min)
• Status of apertured cesiator (Biallas, 15 min)
• Status of ion implantation (Biallas, Siggins, 10 min)

This Week's Attendees

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

Discussion

G. Biallas reported that progress on the cathode shield is on hold because the lead designer is away from the Lab for about two weeks. Nonetheless, he believes it will be ready for installation during the June down. One complication is that the end of the stalk needs to be remade to inhibit binding with the shutter mechanism after establishing a temperature differential from a heat clean. Of course, if we cannot find a way to bring the gun to voltage after high-voltage processing the electrodes with the cathode retracted, the shutter will be useless. So, what we learn from the present attempt to process the electrodes with the cathode retracted will bear on the utility of the shutter. At this writing, the outcome is uncertain.

Detail design of the apertured cesiator has progressed to the point of being able to submit a portion of the job to the Machine Shop. There was considerable discussion at this meeting concerning how to align the nozzle with respect to the aperture and the cathode. Biallas advocated adding a mirror (metallic wedge) at the nozzle end and a window at the valve end so that alignment might be done with a light source. To do so is not trivial. C. Sinclair pointed out that the window would need to be heated to keep it from being coated with cesium. The question of alignment was left unresolved, save for an acknowledgment that much of it can be done during the processes of assembly and installation, the latter possibly involving help from the Alignment Group. Biallas offered that it is straightforward to include an alignment support at the valve end that would still permit easy insertion/extraction of the nozzle. There is a lesson to learn from all of this: designing and building a new style of cesiator is neither necessarily quick nor cheap, unlike initial thoughts advanced at earlier meetings.

Concerning ion-implantation studies, C. Bohn reported on the question of who will do the field-emission measurements on the sample disks. In discussion with D. Manos of W&M earlier in the day, Bohn ascertained that W&M is planning only to do the ion implantation. They are "not interested" in polishing samples (which is no longer an issue given that D. Bullard is doing the polishing), nor are they interested in taking field-emission data. However, it is probably possible to line up some of Lingling's time to assist in taking the FE data, but JLab needs to take the lead on that. Moreover, C. Sinclair's HV test chamber is required; W&M's will not accommodate 6-inch disks.

Biallas reported that two 6-inch disks made from high-quality ball steel were just received and turned over to Bullard for polishing. The remainder are due in shortly.

Closed Action Items

• Bohn: Discuss with D. Manos how we can obtain the field emission data for the ion-implantation studies. Status: See "Discussion" section above
• JLab needs to take the lead.

New Action Items

None.

Old Action Items

• Biallas: Procure "best quality" (vacuum remelt) steel for the ion-implantation studies. Have JLab Machine Shop make the plates. Status: Two plates were just received, and the remainder are due in soon. D. Bullard is lined up for polishing. Will drop this as an explicit action item once all disks are received.
• Sinclair: Prepare procurement package for DLC-coated samples for Dylla's signature. Status: Based on the plate drawings, Biallas will get a quote. (due 29 Apr 99)
• Siggins/Biallas: Specify design of experiment to measure cathode temperature. (due date TBD)