ELOG Test-Stand

Friday, July 30, 2021, 16:32: Emittance meter power supply found at 500 V. Running a scan does not weep the voltage.

Friday, July 30, 2021, 17:43: TBHT reached set current. TGHT @ 304 A and ramping up. IG1 @ 6.36e-7 T. TIS glowing so I guess it didn't break from early trip.

Friday, July 30, 2021, 21:24: Mass scans with gas on/off shows clear only contribution from gas line.

Friday, July 30, 2021, 21:25: Anode=200C,Coil=30A. FC0=5.14e-9 A. FC6=9.35e-10 A for 40Ar+

Parameter scans performed on nominal heater current and also with heater at similar power to older measurements.

Leaving some devices that are typically at 0 V to something like 1 to 2 volts, to avoid the red 0 readback as a test.

Saturday, July 31, 2021, 08:13: System stable overnight. TMS:VCB5 was the only device found off.

Sunday, August 01, 2021, 08:42: On-site: Grid is fine. Gas pressure stays at |200kPa| even after several line flushes. Continuing remotely.

Several parameter scans all at 280A. All of the look remarkably similar, so reproducibility over two day is possible. Mass scans at three different coil-anode combinations

Emittance scans still not possible @ 1.3e-9 A on FC6, when going to 290 A will try again.

Mass scans performed. Emittance scans are still not possible with FC6=2.2e-9 A. Parameter scans

Parameter scans. Mass scans performed. Emittance scans are still not possible with FC6=6.21e-9 A. I think there is something wrong with the parameters or with the hardware. To check with Carla on Tuesday.

Monday, August 02, 2021, 20:44: Ran some tests with the older tune as it provides a broader beam. With this the emittance meter is able to detect the beam center at 85 mm as is common with this tune. However, the beam is not scan in angle, that is the voltage is not swept. Not sure if this has to do with a stuck power supply, or if the voltages of the plate are not biased.

I will take one more measurement at higher current and go tomorrow to check the emittance scan status.

Monday, August 02, 2021, 20:46: Auto-ramping TBHT to 310 A @ 1A/min. IG1 @ 8.16e-7 T.

Tuesday, August 03, 2021, 11:55: Emittance scans seem to work now( see e-log 891)

Tuesday, August 03, 2021, 20:21: Ramping TBHT to 315 A @ 1A/min. IG1 @ 8.2e-7 T.

Tuesday, August 03, 2021, 22:55: IG1 @8.07e-6. Done for the day. Will continue tomorrow.

Data analysis on files generated so far. Efficiency as a function of temperature-voltage look similar.

Given that previous cathode heating current did not have emittance, I will go down to measure efficiency.

Thursday, August 05, 2021: Morning troubleshooting CANBUS signal with no luck (this is actually something good)

Saturday, August 07, 2021, 06:00: Found all my epics windows closed. Probably a network issue as I cannot connect from any of my pc's. Submitting a ticket.

Saturday, August 07, 2021, 08:43: Reply from Steve McDonald says there are general network issues and someone is goin on-site to investigate the "network switch stack in the ISAC2 second floor"

Saturday, August 07, 2021, 15:06: FC0 reading oscillates a lot and sometimes drop to 0. Mass scan shows almost no peaks without gas. With gas, the FC0 behaves the sames even thought 40Ar+ signal is 1e-8A and responds to the gas open/close.

ISAC test stand PC lost connection to epics due to the same issue. Initiating striptools.

Nothing visible wrong on service cap nor around the ISAC test stand, however, FC0 still oscillates a lot.

I will change the signal cables to see if one controller can read from the other faraday cup.

Sunday, August 08, 2021, 00:35: Ramping TBHT to 300 A @ 4 A/min. IG1 @ 6.71e-7 T.

Sunday, August 08, 2021: Parameter scans, mass scans, emittance scans performed.

Sunday, August 08, 2021, 23:55: Checking other species given that with TBHT=310 A I can see m=90, which I think it might be Ta++

Investigating the following species: O+, (H2O)+, Ar++, (N2)+/CO+, (O2)+,Ta++,(TaO)++ on masses 16,18,20,28,32,90,98, respectively.

Both the atomic, and molecular oxygen follow different tendencies wrt other species.

Tuesday, August 10, 2021, 10:01: Increasing anode limit current to 200mA. All previous tests had 150 mA and the maximum current recorded was ~110mA.

Tuesday, August 10, 2021: Mass 60 observed, it might be (SiO2)+ coming from the coil jacket. The parameter scan shows that the ion current is only dependent on voltage.

Wednesday, August 11, 2021. Mass scan, and parameter scan. For the first time I am measuring only FC0 with and without gas. I'm gonna investigate the higher peaks individually, likely they are H2O,O2,O,H2, and Ar

Thursday, August 12, 2021: All day measuring different ion currents with and without gas (H2,N,O,OH,H2O,N2/CO,O2).

Friday, August 13, 2021, 19:50:Scans completed for different species, results seem consistent but required more in-depth. FC0 scans shows higher values towards high anode voltage and high coil current but not all species shows this behavior.

Saturday, August 14, 2021, 22:28: Parameter scans, mass scans. Some emittance scans unsuccessful.

Anode leakage current seems to creep a bit overnight. This could be an indication of a failure onset but I'll have to see. I won't increase the current remotely until being on-site

Sunday, August 15, 2021, 10:10: Anode leakage current has increased 10 mA overnight.

Sunday, August 15, 2021, 20:43: Emittance scans for multiple anode/coil combinations. Visually there are differences on the geometrical emittance, not so much on the 90% intensity emittance. Requires proper emittance analysis.

Monday, August 16, 2021, 18:58: Data analysis and short summary. Systematic emittance measurements.

Request to add more PVs to control emittance and mass scans from jupyter notebook

Tuesday, August 17, 2021, 10:22: On site. Grid is fine. Re-initianing epics as my pc reboot it.

Tuesday, August 17, 2021, 10:23: TBHT to 335A @ 1A/min. Anode leakage current =150 mA. IG1=6.51e-7T. Increase anode current limit to 250 mA.

Tuesday, August 17, 2021, 10:29: ~~The grid is as bright as the cathode. This is the first time the grid shines this bright.~~

Tuesday, August 17, 2021, 10:53: The grid looks normal at anode=200V. By making an anode sweep I was able to observe that at around 300 V there is an onset on how bright the anode get. Passing this voltage the grid start to shine and gets a maximum brightness when reaching 500V.

This seems to suggest that the power deposited on the grid is enough to cause substantial heating if it makes it as bright as the cathode. The maximum power into the anode body (at this cathode heating current (335A)) is 500V* 200mA=100W (just like a lightbulb)

Tuesday, August 17, 2021, 20:19: Anode is drawing more current. During Ar+ scan, the maximum anode current registered was ~200 mA. Now is ~250 mA

Tuesday, August 17, 2021, 22:16: Once again, at the end of the scan the current increased. This time to 320 mA

Tuesday, August 17, 2021, 22:18: I think the grid will melt tonight with anode/coil @ 200V/30A.

Wednesday, August 18, 2021: Well, well, well. Grid didn't melt but the anode leakage current has increased again. At some point the anode got current limited to 350 mA and from 490 V it drop to 470V.

Wednesday, August 18, 2021, 18:01: During the scan on FC0, the anode current went up to 400 mA so I increased to 500 mA, but I had to increase to 600 mA but it was still getting current limited. Scan aborted

~~I will run an FC0 scan with gas on while I'll go on-site to check the grid and the "anomalous" ionization..~~

Wednesday, August 18, 2021, 19:42: Grid is melted. From the look of it half of the visible part collapsed into a blob while the other is gone (allowing to see the far backside of the target oven.

With this knowledge I can proceed with more aggressive tests in order to test the limit if the "anomalous" regime.

Wednesday, August 18, 2021, 23:24: After a mass scan with 0 V to check surfaces ionizes species I noticed there is a signal on mass ~ 137.5 which I am not sure what it is.

It might be Ba or a molecule but is coming from the transfer line as sweeping the voltage between 0 and 2 V changes the response but above this the signal is gone and reappears with 80 V.

Thursday, August 19, 2021, 08:08: mass ~137.5 disappeared. If I increased the anode voltage to 400 V or so some appears but quickly drops.

Thursday, August 19, 2021, 14:08: Scan didn't cause an increased on leakage current. Maximum registered was around 200 mA. However, the contour plot looks different to the case when the grid was complete.

Thursday, August 19, 2021, 23:36: TBHT to 280A @ -1A/min. Tomorrow I will focused on temperature scans without caring much on emittance o mass composition.

Friday, August 20, 2021, 11:28: Scans done for,280,285. Currently running 290 A.

The coil current dependence qualitatively follows the one from ISOLDE, in which a series of minimum and maxima occur and also vary a bit with voltage.

Friday, August 20, 2021, 13:34: Accidentally set TBHT to 226 A directly from 295 A.

Friday, August 20, 2021, 14:13: TBHT is at 295 A to check things are still the same.

Saturday, August 21, 2021, 18:11: The voltage got current limited during the scan for 345 A. When setting the voltage to 0V, the anode seems to be shorted.

Saturday, August 21, 2021, 22:46: Ramping down TGHT/TBHT to 0 (@-1A/min) but the short is still present. Currently @ TGHT/TBHT 454/162 A.

Sunday, August 22, 2021, 13:29: This morning the heaters reach 0 A but the anode remain current limited. I will proceed to turn off the TS to check tomorrow morning the ion source.

Monday, August 23, 2021, 08:30: Confirmed a short between target/cathode to anode/heatshield

Monday, August 23, 2021, 11:29: Confirmed that the anode power supply still works :)