The resistor/varistor combinations across the target + / -, tube + / - and target- / tube + have been remade and moved to the back of the power supplies to limit the corona discharges at higher voltages. Pictures attached.

First attachment: BIAS/EE/EZL = 63.25/-1.5/31 So far no issues.

Second attachment: BIAS/EE/EZL = 64.25/-1.5/32 Slight spark - bias current jumped from 40uA to 88uA and vacuum jumped from 2e-7 to 2e-6... Steerers went off.

Third attachment: BIAS/EE/EZL = 65/-1.5/32  Some small signs of instability in the bias power supply

Fourth attachment :  BIAS/EE/EZL = 65/-1.5/32  Been running for 20 mins now. More variation on the bias current output than at lower voltages but not too bad

Pressure:

Ramping up:

• Second attachment - bias at 50kV
• Third attachment - bias at 60kV
• Fourth attachment - bias at 65kV

Pressure has been slowly falling since we started this test - now down to 8.7e-7

Spark after 10 mins, see attachment 5. Very slight vacuum jump (8.5e-7 -> 1.2e-6) and bias current jump (36uA -> 113uA). Tripped TP6 and the steerers, as usual. Bias current read back more erratic afterwards (see sixth attachment).

System has been stable for 20mins, though current on bias is still more erratic than before the spark. Increasing He leak rate from 7 to 7.06 to bring vacuum back up to 2e-6 (see attachment 7). No effect from increased pressure.

Tuesday, March 13, 2018, 05:52: Power off.

Tuesday, March 13, 2018, 05:56: Waterlines purged

Tuesday, March 13, 2018, 05:57: Ion gauge, Turbos off.

Started with Anode at 25V and coil at 0A, bias at 30kV. (attachment 1)

Ramped coil to 60A (0.4V) (attachment 2)

Ramped bias to 51kV, but then TP6 turned off and there was a momentary 0.2A decrease in the TGHT current. No spike in BIAS current seen, maybe TP6 is turning off for another reason? (attachment 3)

At 57kV, a small spark, heard outside the vacuum, sounding like it comes somewhere near the blue racks which hold the power supplies. It has sounded like that to me before. Did not turn anything off but bias current spiked from 110uA to 280uA. (attachment 4)

At 57.5kV another spark, taking down TP1B and TP6, as well as the CB1 steerers and TPS:Q1/2. TGHT current dropped momentarily from 581A to 240A, or so says EPICS. Maybe just a communications effect? Voltage for TBHT also dropped but nothing seen on TBHT. Coil current and voltage also showed small effects. (attachment 5)

After 10mins at 60kV, spike in bias current with slight spike in EE current but no other effects.

After 20mins everything has been stable, will turn the bias back to 30kV. As I turn the bias voltage down, the EE current ramps up. No change to EE voltage... (attachment 6)

The fan in the EZL power supply is making a terrible noise - keep an eye on it, it sounds like it might give up soon.

Monday, April 23, 2018, 10:47: The back panel was opened. Original entry stated EZL power supply issue. Corrected to BIAS PS. High voltage group notified. Fan replacement required.

Monday, May 14, 2018, 13:20: BIAS fans, external an internal were replaced. Re-installed @ TS.

Monday, May 14, 2018, 13:26: BIAS ramped up to 10 kV. Response ok on epics and locally on the PS. No odd noise on the fans either. The issue appears to be fixed.

TM4 source tray left in test stand over weekend, just the rouging pumps on. Ready to be removed Monday morning.

Monday, June 10, 2019, 06:35: Venting - Aaron S.

The wiring on the top of the test stand was burned, see entry 737.

Probable cause of this is as follows:

Coil lines are connected by a wire to HV common, the 9-pin feedthrough etc to maintain same voltage on all the insulator tops. This is also directly connected to the extraction electrode spark gap. When this sparks, it momentarily changes the potential in that line (normally HV common) which then can make this path the best route for current from the coil to return to ground.

See attached diagram.

Best solution to this problem is to disconnect the high current section from the low current section, and attach each separately to HV common.

Other possible improvements to wiring:

1. Remove jumpers between positive coil lines (and neg. coil lines) since these feethroughs are physically connected by the copper pipe.

2. Add a resistor to the jumper between coil - and TBHT - since this will eliminate all possibility of current flowing between the two.

3. Add a resistor in line where the high current section is connected to HV common to avoid possibility of current going through jumpers.

Tuesday, December 01, 2020, 11:56 :

TSG:BIAS unplugged and controls pigtail (made by Ray) added in order to connect controls cable to TCS:BIAS, which is now installed in the same rack.

Basic controls testing done without turning on the power supply, controls max values scaled to 75kV, 5mA.

In process of grounding all features inside the faraday cage. New grounding will be marked with a label for easy identification later.

NOTE: we should get together in January to discuss test stand wiring, since I discovered another burned up connection (see next elog entry, #823).

Tuesday, December 01, 2020, 16:47 :

Grounding of all feedthroughs on the service cap complete and continuity checked.

Removed gas line with Fernando's approval, to make more space for our feedthrough.

Awaiting nylon insulator to proceed.

Between feedthroughs F (magnet coil) and B (tube heater negative), I found a jumper with two resistors that has been burned up. I am not sure when this happened, but it would be good to review the overall setup of the service cap wiring in the new year.

The cable connected to feedthrough Q where the multipin sits also looks burned.

Wednesday, December 02, 2020, 08:31 :

Added copper wire connection to multipin screw terminals in HV cage to make sure they are grounded.

Attached grounding rod to back of HV cage. Not ideal, but couldn't find a better place without making a extension to the cable. Will see what John Chow says. EDIT: John says it is ok for the tests, not for permanent.

Vented test stand to swap window positions. Swapped rightmost window on the door with two windows with window on the door with only one window. Replaced one oring, that on the single window. Cleaned the inside surfaces of both windows with methanol before re-installing. Roughing down just to make sure there are no major issues, at 0.313T and falling. EDIT: down to 0.015T overnight.

All breakers on HV cage panel are OFF.

Friday, December 04, 2020, 08:52 :

Test stand roughed down to 29mT overnight. Started turbos for testing later.

The copper tubes to be used in the TM3 test piece may have flux inside them from soldering the end caps on. There are holes along the length for outgassing, and we will try to bake them out in the test stand before installing them. There is still a dummy bake out target installed there, see the photo for how the tubes are loaded in. TGHT ramping started around 3pm.

I had to remove the grounding connections from the TGHT feedthroughs for this, so I redid them such that the tube is attached to the EZL. This target has no tube, so the connection between the tube and target is just through the 100Ohm resistor.

We must re-do the grounding before proceeding with HV tests.

Wednesday, December 09, 2020, 19:38 :

Target heater ramp down started. See attachment for vacuum progression during bake out.

I have rewired the test stand (service cap wiring only, not power supply wiring) to anode bias mode as shown in the diagram. This was not how it was wired before, there are several things I have removed that appear to be newer additions. I also removed the burned cable between TBHT(-) and COIL(-), and between the multipin feedthrough and ground (probably related to the other burned cable).

I tried to measure the resistances across the feedthroughs (as opposed to across the resistors themselves) but they all seem wrong. I get 27Ohms across the TGHT and TBHT circuits instead of 100Ohms. Between the TGHT and TBHT I get 100Ohms as expected. Across the coil circuit I get 6Ohms instead of 100Ohms. Probably only the 6Ohms really needs to be fixed, but if the resistors are damaged, then the varistors might be as well.

Wednesday, March 10, 2021, 10:48  : Venting beamline section only for installation of emittance meters.

Monday, March 15, 2021, 16:09 Target and ion source ramped to 400A/330A this afternoon

Monday, March 15, 2021, 18:53 : Tune through to final RPMs but not optimized. 5e-8 on FC0. Will turn down target and ion source values to TGHT/TBHT 350/250 until tomorrow. BIAS/EZL/COIL/ANODE all off.

Tuesday, March 16, 2021, 15:04  Mike is finished with emittance meter controls so ramping everything back up and trying to get beam through.

Thursday, March 18, 2021, 18:06 : Vacuum has been rising slowly over the past 20hrs from 9.3e-7 to 9.9e-7. Everything has been up since Tuesday. No beam through emittance meter, though beam can be found on the regular test stand emittance meter. Just discovered that both voltage plates are plugged into positive power supplies so waiting for a controls fix on that then will retry.

Friday, March 19, 2021, 17:08 : Finally success. New emittance meter shows same results as the standard test stand emittance rig. Will continue testing new controls next week

Vented beamline and removed ARIEL emittance meter. In the process of swapping components, beamline left vented until Monday when we will finish the job.

Emittance meter number 2 ready for beam shortly - installed and pumping down.

No beam found by Thursday evening, but beam seems to be coming out much differently than last time. Will check on emittance meter functionality and try to re-tune later.

Ramping things down for the next couple days.

Saturday, April 03, 2021, 10:41 :

Source heating ramped back up, everything back on. Will try to straighten out steering then see if I can get things back in the previous positions.

Saturday, April 03, 2021, 14:59 :

Nothing seems to be working, will vent the beamline and remove the slit.

Saturday, April 03, 2021, 15:36 :

Apparently closing the valve started a vacuum leak that tripped everything in the source. I noticed within the first minute and ramped everything back up, maybe too quickly....

Have now put everything in a holding state, will resume tomorrow.

Sunday, April 04, 2021, 14:17 :

Found everything off again this morning. Ramping back up in the hopes that I can get something done before the whole system trips again. The trips look like water leaks again.

Uninstalled the slit and left it in the bottom of the vacuum box. Swapped the window to the computer side for convenience. Seal on the other side on the CF flange is a bit weird, not sure if it is in properly...

Sunday, April 04, 2021, 18:43

Still no beam. TISA emittance FC won't come back on, so waiting for Mike Rowe to troubleshoot on Tuesday. Will ramp things down all the way, since I expect the vacuum to trip the source before I need it again.

Tuesday, April 06, 2021, 23:43

Found some beam, but looks really weird, like it is cut off. Good enough. Ramped everything down.

IG1 has been spiking randomly, causing everything to turn off. Looks like the water leak is still there.

AS - Multiple purges done on RP1 & the backing lines. Some water noted. FS#3 is closed.

Tuesday, April 06, 2021, 09:39: TP1B on.

Tuesday, April 06, 2021, 10:01: TP1A on.

Tuesday, April 06, 2021, 10:12: IG1 on. Vacuum @ 1.97e-05T.

Tuesday, April 06, 2021, 11:00: FS#2, #4, & #5 open. Vacuum @ 5.73e-06T.

Tuesday, April 06, 2021, 11:12: Vacuum @ 5.09e-06T. Open FS#3.

Tuesday, April 06, 2021, 11:17: IG1 @ 4.64e-06T. Open IV4. Reset optics & sources.

Tuesday, April 06, 2021, 11:20: Optics on.

Test were run

Thursday, April 08, 2021, 10:30: Power / sources off.

Thursday, April 08, 2021, 10:34: IG1 & turbo pumps off.

TP1A tripped off on Fernando, seems the backing pressure got too high. Even with PV1 closed the RP1 pump could not get below 200mTorr. Derek from vacuum group came and had a look, and is swapping RP1 out for one of the vacuum group pumps, then will see if they can repair ours.

Connection of TBHT negative to HV common removed (R4 in circuit diagram). Labelled and put in MRO bucket.

Anode connection moved to feedthrough J.

Rewired multipin patch panel. Left some grounded (HVC) wires hanging, should probably make this nice later.