Testing!

My first OLIS elog entry.

test

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.

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.

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.

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.

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.

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.

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.

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.

Main event this morning so far: mass scans and post-scan analysis using Gabe's tools. We have a pretty good recipe now. Tight scan to mass 20 in progress. Later... good scan. Geoff and I did a dry run of our presentations for Friday morning. We used the Auditorium computers, etc. After some small teething pains, everything went well, including a cold start-up of the source. The 17O3+ emittance scan was taken quickly. Pretty good outcome anyway. The mass scan shows nice peaks at several known points: 1H+, 2H2, 4He, 7Li, 12C, 14N, 16O, 19F and 20Ne. Gabe's Calibrate tool returns values for the two constants that are pretty close to what is there now: -1 and 0.0419 calculated versus 0 and 0.0418 actual.

We handed over the beam to Sophia for testing Rick's new tune. Although there are RF issues at the RFQ presently, her feedback to the operators is so far, so good. TBC tomorrow morning. Right now, we will open the OLIS cage and install a couple of source gases in preparation for our presentation on Friday.

Krypton source gas teed directly into ion source. A Nupro valve and tee also added for 17O line. At present, the 17O gas bottle valve is closed. The Kr bottle has an integrated leak, so this bottle is opened to the system now. Pumping in progress. Pressure is already <3e-7 Torr. I will restart the source shortly.

Pumping went well overnight. TP3 turned on around noon. Issues with Kepco communications.

Presentation this morning in Auditorium. Players:

Keerthi: science

Geoff: engineering

Damien: operation

Cold start-up of source with 17O3+ beam to FC6 in front of an audience worked flawlessly.

A comment about RF power came up at the presentation this morning. Intense X-rays can be produced not only at the peak efficiency and output of the RF amplifier but also as a function of other parameters including source gas pressure, isotope(s), whatever you can think of. I set the RF at a mid-level power, with power setpoint at 0dB and adjusted the RF for optimal current on FC6. This occurred at 13.0306GHz with 35W power. About 6nA of beam. Take a quick emittance scan.

We began looking at 84Kr this weekend. Keerthi had 84Kr19+ on FC6 this morning, which I was able to tweak up from ~300epA to about 600epA. Not bad! This evening it is down to 100pA at best. I think there is a correlation of multi-charge production and room temperature. (It's warm today.) Keerthi noticed tat an entire mass scan this afternoon was suppressed, where I had a solid scan earlier, the two taken the same way. Let's see what happens to FC6 overnight.

Damien Gallop wrote:

We began looking at 84Kr this weekend. Keerthi had 84Kr19+ on FC6 this morning, which I was able to tweak up from ~300epA to about 600epA. Not bad! This evening it is down to 100pA at best. I think there is a correlation of multi-charge production and room temperature. (It's warm today.) Keerthi noticed tat an entire mass scan this afternoon was suppressed, where I had a solid scan earlier, the two taken the same way. Let's see what happens to FC6 overnight.Beam d

Beam definitely correlated with something overnight. I'm going to say that temperature somehow affects MCIS vacuum, which in turn affects the generation of the higher charge states. We will investigate this further. We did a couple of mass scans this morning. I have closed off the krypton gas bottle to get a background scan. Here is the preliminary one, started a few minutes after closing the hand valve. You can see the clump of 84Kr charge states between approximately masses 4 and 10. Another scan to come shortly, with everything the same except an hour's delay after closing the valve. Here it is, below. The height of the "clump" is less, and it begins more to the right of mass 4 or so than the earlier scan. Note that the small amount of 84Kr remaining after shutting off the source bottle is slightly offset on the plot. I will recalibrate the numbers shortly.