I have been testing various RF power settings for cold starts and beam stability. No surprise, the best tuner setting is approximately midway at about 58%. Different slit selections tested. Emittance scans in progress. Done.

Keerthi started the Supernanogan source today. His primary goal was to test out Rick's theoretical tune calculations. He was ecstatic with the results. Rick's table gives a tentitive value for the Einzel lens. In fact the ideal value is at or even higher than the bias voltage. However, Keerthi experieced sparkdowns at those voltages. Rick's calculation gives a reasonable number for better than 50% transmission between MCIS:FC0 and IOS:FC3. The Enzel lens at full chat (10KV with the present power supply) gives a transmission of close to 90% with 11.5KV bias. So far, there are no sparkdowns. Keerthi suspects a resonance effect with the earlier sparkdowns. Presently we are observing beam and optics stability, with about 16nA of 17O3+ on IOS:FC6. I'll do some scans in a while.

The TIGRESS run ended this morning. Supernanogan Development begins now for two weeks. Begin an 18O1+ emittance scan and also take some fast FC6 current measurements before we switch over.

The MWS delivered 18O overnight, mostly onto FC6. Sophia complained about source stability this morning. It definitely could be improved. Yesterday Keerthi did some online tweaking of the RF power for stability, with little improvement. The IOS pressure today is about 2e-6 Torr, so I believe the 18O pressure is too high for good operation, although the brightness is great. The base pressure is about 4e-7 Torr. Tuning is in progress. Given an opportunity, I would like to try one or all of the following:

1. Tweak RF power

2. Change 18O gas delivery to use the calibrated leak

3. Leak check the IOS section. Vacuum Group knows we would like to do this on short notice.

Later... Marco denied time for a look-see, even when they are ruminating. I had stripped various things against beam current, and did not find a strong correlation except separator field. It is blazin' hot around here today, and for sure equipment is having a hard time. I had hoped to turn off the magstab program for a few minutes and see where things go. Marco's reply was, they are happy with the beam as it is. Done deal.

A couple of weeks of 17O3+ to DRAGON ended yesterday with a photo finish. Supernanogan went off at 10:00. Preparations for 18O began. Main event for yesterday: Replace IOS:TP7. Edi Dalla Valle reported that he had just received a V550 with Conflat flange. "Our timing was perfect." It is working well. The system was under vacuum again by around noon, and pumped overnight. This morning IG1 was ~5e-7 Torr and IG4 was ~2e-7 Torr, where those two gauges were the other way around previously. We attempted to do a leak check, but could not get it coordinated in time. So by 15:00 we chose to start the MWS and hand over the beam to the users.

Present MWS source gas setup: enriched 18O attached in two places; the straight-through path is open, while the calibrated leak is closed. We approximated the appropriate pressure on the regulator, allowed it to bleed down, then reset it to slightly under. The bottle valve is open. The bottle pressure is 150psi right now. At this rate, the cost of the source gas is about $200/day.

Vacuum Group applied a temporary fix to the lower body seal on IOS:TP7, which we found last night to be leaking. Edi tells me that similar seals have failed before. It's an O-ring, not a metal seal. The fix now was to marinate the outside seam with silicon grease and wrap with Teflon tape. We'll see how that improves the backing line after a while.

Meanwhile, Vacuum Group is setting up to leack check the work.

The previous 18O4+/8+ run to TUDA-II finished midday yesterday. OLIS was prepared for 17O delivery from the Supernanogan source. Leak checking was done last night. The big offender was a failing metal seal on IOS:TP7. The pump will have to be replaced. Meanwhile the pressure is sufficient for 20nA of 17O3+ with 2.5mm (middle selection) apertures inserted. Present agreement is to leave TP7 as-is for this run.

End of run diagnostics done. See ISAC elog. Supernanogan cart is already installed and at high vacuum. Prepare to run 17O from Sgan sometime over the weekend. Today's agenda:

1. Close 18O bottle and gas valves.

2. Isolate IOS:CG0 to minimize pressure contribution from long copper lines.

3. Work around gate valve interlocks.

4. Set up for leak checking: IOS first.

We did some preliminary vacuum checks, and found significant loading on the IOS turbos, probably downstream near DB6. Leak checking now in progress.

test

My first OLIS elog entry.

Testing!