We discussed whether or not to leave the Supernanogan in the OLIS Faraday cage, and decided no, because the up-coming runs will use the MWS at 42 and 52kV respectively, higher than the MCIS HV rating. Bonus: We have more working room in the cage. The cart is out and parked. Services are connected and up.

Run Plan:

• Remove MCIS cart.
• Set up for leak-checking MWS gas manifold.
• Pump manifold through IOS volume.
• Repair leaks as necessary.
• Pump.
• Start MWS with 21Ne beam.

 Beam to scheduled user at 08:30 Friday. TUDA-II safety commissioning is planned for Thursday. Sophia will need beam prior in order to set up into SEBT.

With the MCIS cart removed, Geoff hooked up the leak detector to the MWS source gas line. He did a couple of hours of leak checking in this mode. Then he moved the connection to an empty gas port on the manifold itself. Much qicker responses. We replaced a VCR seal on the bottle side of the right-hand He solenoid valve. That did wonders. He checked around afterwards, but found no further leak. We tidied up and opened the manifold to IOS. Base pressure was about 1e-6 Torr and holding. After an hour or more, I decided to reinstall the leak detector on the manifold to assist pumping. I suspect air trapped on the front-side of the flow controllers. Opening them wide caused a vacuum spike, which recovered. It all seems to be working, and that is where we are right now.

Vacuum came down to ~7e-7 Torr. On startup, bias sparked over somewhere. Vacuum leak was caused. Later we found that HV had sparked through the source gas tubing, which was touching the beamline frame. Obviously an arc had formed within the tube and sparked through on the ground side. We also could not reset the bias interlock (ICR has efaulted this), so we ran in local. System is set up for 21Ne with about 28nA on FC6. Bias is off for the night, while plasma remains on. Bias can be turned on at will, preferably via EPICS. Fine-tuning will take place mid-morning Wednesday.

Other notes: Neon gas line checked for any sparkover leaks. None. It was closed down and pumped during the course of leak-checking today. Checked: bottle valve open, and line valve open. Plasma electrode in this mode is best near zero. About 3V is good, which locks in one plasma mode. At zero and with the quartz  liner "can" installed, the plasma could toggle through different modes as plasma wanders back and forth through the plasma chamber. Also, microwave power can walk the plasma. Goal: Move the plasma back as far as possible so that a clean beam exits the source, i.e. good beam on cups with relatively small spills on collimators. In an otherwise identical setup but without a liner, the plasma would form adjacent to the backplate, a different mode of operation altogether.

Last night Keerthi resolved the sparking issue in MWS and started the source while I was present. There was a frozen interlock condition ion IOS:BIAS, which Graham resolved today. HV was on by ~11:00. Beam on FC6 immediately. It looks like Sophia took the beam at that point. I noticed that the Kepco appears not regulating, and in any event is close to a limit (0.3A). I have asked Sophia for five minutes to reset it.

It turns out that the system cannot see the Kepco on the USB port. This has occurred before. It will take some investigation... later. Also, the gaussmeter is reading erroneously, and MagStab iappears to have picked up the EPICS probe values instead, although no field corrections are being made.

21Ne has been available from the MWS since mid-week. Here is roughly how last week unfolded to now:

Monday: MCIS -> MWS and remove MCIS cart
Tuesday: leakcheck MWS source gas manifold
Wednesday: Controls fixed interlock oddity on IOS:BIAS
Wednesday: Begin setup for TUDA-II
Thursday: continue tuning to TUDA-II
Thursday: prepare to commission new SEBT NIM
Friday: commissioning of new SEBT NIM
Friday night: begin setup of beam to TUDA-II
Saturday: 21Ne5+ delivery to TUDA-II began at about 07:30 for the first time
Saturday: 21Na5+ delivery to TUDA-II switch at about
Saturday evening: power bumps knocked out OLIS and other systems - thunderstorms - go idle for the night
Sunday afternoon: check tune with pilot beam
Sunday night: resume RIB delivery

I expect several energy changes over the next little while.

At the Beam Delivery meeting today, we discussed the up-coming 25Mg run, which has scheduled a mere 48h of turnaround time. I made it known that there is *no* margin in that time allocation. I put in a bid for the preceding Friday, August 1st. Marco didn't think it would be available that soon.

Conveniently scheduled for BC Day, we are preparing to switch over the MWS to sputter operation with MG source material. Operations has saved present 21Ne tune.

Later... Done! Source is relit with 21Ne beam on FC6.

Summary:

• Vent IOS to Ar
• Remove MWS backplate
• Machine Mg metal disk (source material) for mounting screws
• Hand-cut Mg disk in two halves and clean
• Clean backplate
• Attach disk halves to backplate
• Clean assembly
• Reassemble at OLIS
• Pump - roughout was fast
• Pump - turbos on
• Minor MRO
• Button up and go with previous settings.

We will let it run this way overnight and shoot for an Mg plasma and beam tomorrow.

Attached below are plots of the last few hours of 21Ne beam. PDG, I'd say. Note the variation in sync with room temperature.

The source stayed up overnight just fine, with a little 25Mg beam on FC6. This morning I did a few mass scans to get a fix on Mg positions. Short story: There are some 3nA of 25Mg on FC6 presently, with things less than optimal. Stay tuned.

Attached is an early graph of Mg beams produced with the MWS almost exactly five years ago. Best I could find for now.

Later... Tuning went well. I ultimately had to tune in the ICR due to network response outside as people came in, etc. There are some 10nA of 25Mg on FC6 now, and the tune is set up for RFQ delivery. Snap: 090804_1240.snapiosfc6. I tweaked the upstream vertical steers slightly afterwards. The front-end differs from Rick's numbers by a bit, but it's necessary to keep down spills onto optics and get the beam through. I'll attach the differences below. Meanwhile, here are stripcharts of FC6 for the morning. In the latter part you can see where I turned down the microwave power from 600W to 500W. Slightly more than 500W seems about right for equilibrium. But to avoid boiling let's leave it at 500W for now.

A decent emittance scan is in the ISAC elog, albeit I ran it with slits closed down, so it should be repeated at some point with slits open.

So... there evidently was a power bump overnight, because the stability power supply was "disconnected" from the system. This happens every time there is a power bump. It's a serial port thing. Meanwhile, the source also tripped. Upon restart, nothing was the same. This morning, we found that Q3 was current-limiting on one element. We have asked Rick to develop an alternate tune for us.

Keerthi did some source tuning early this morning. We since shut it off for the swake of Q3. I have restarted it now temporarily. Here is an emittance scan with slits open and Q3 off. Now we will shut off again to prepare Q1 & Q2 supplies for new numbers.

Tuning...

Tuning has been on-going through the day. Here are a couple of emittance scans taken in-between heartbeats. The first is zoomed out, the second zoomed in a little close. We managed to sneak in a third also.

While there is an SC cavity issue, I have been repeating last evening's emittance scans. Here is the best one. About 70nA of 25Mg on FC6 presently. Note that emittance rig Faraday cup is reverse-biased. Also, overnight stripchart appended. You can see a gradual increase in current draw on the EE power supply as there is a build-up of Mg.

Later... Rick analyzed this scan and came up with his own numbers, with which he is happy. Here is his pic.

Around noon, Keerthi adjusted the PE down to reduce the intensity of the Mg beam, as we are running with attenuators in. He ended up with about a 30% reduction, and improved the noise band by about 3x in the process.  Here is a repeat emittance scan. Both sets of slits are at 2.5mm position. I also took the opportunity to reset the separator stability equipment again.

Interesting, the beam took a step down a couple of minutes after hands-off. A tweak on the separator suggests that it's already about optimized. Well...

Sophia is back to tuning now.

Summary: good.

Details: A trip occurred at some point. I restarted the source over the weekende remotely. I have been tweaking down the PE since. Looking mighty fine. Stripcharts attached. Separator field nicely flat too, with stability program running. Save: 090810_1605.snapiosfc6

A series of 25Mg emittance scans for Rick.

Starting scan with everything as-is, i.e. slits closed.

Data file: 090810_1621ILTEMIT.txt

Before proceeding, I nudged in each of the slits, watching for first clipping. With the current emittance (nice), the beam cleared both slits completely; the upstream slit began clipping at about 1.5mm, and the downstream one at about 2mm. Also, FC6 current with slits in/out was: ~30nA / ~57nA. Note: I had to change the scanner parameters a little.

Data file: 090810_1648ILTEMIT.txt

Here is the emittance scan that Rick requested, beam with Q4/5/6 off. Note that present numbers for these quads do not match theoretical. I repeated my slit nudge check for clipping, just in case. As before, no clipping for the first mm or more.

Data file: 090810_1713.txt

Here is a variation I thought might be appropriate.

Data file: 090810_1724ILTEMIT.txt

Finally, here is the "original" beam. Can you tell the difference (side-by-side at bottom)? I can't.

Data file: 090810_1738.ILTEMIT.txt

So... we have had this on-going problem with intense Mg beam coating our optics. Keerthi found a good recipe last week with PE on and a somewhat large support gas flow. We have been running with several tens of nA since. Since yesterday's trip, I have been gradually lowering the PE from my initial value of 100V to 30V presently with about 10nA on FC6. Beam looks like it will be very stable, and the EE will maintain indefinitely like this. The first test: Marco just made overtures to use the beam for checking TIGRESS tune.

Well, so it goes. As I was penning a note for OPS, the source tripped. It easily reignited with a little extra Ne. I left the flow slightly higher, from 1.1 to 1.2ccm and the PE at 41V.

As noted earlier, the MWS beam dropped out at some point after yesterday afternoon's playtime, due to insufficient PE. Plasma was lost. I restarted the source remotely. The present combination of Ne flow SP = 1.2ccm and PE = 48V works well. Plasma will persist regardless of Mg presence or PE setting. That's a good thing. Then using the PE we can control how the plasma ionizes the Mg material. Note the attached stripcharts. At the lower PE settings, the Mg loading on the EE is much reduced and indefinitely sustainable at those levels.

Presently the source is off for Supernanogan cart installation. We will have it in and buttoned up by around noon.