Greg G, Nutsinee K. Matt H, (Richard M)

So the plan going into today was to get the CO2Y laser going and to clear the AOM fault on the CO2x table

Things didnt quite go as I hoped though. Due to some miscommunication, the reason that the rotation stage on CO2Y did not work is that it was deliberately unplugged. It had been in this state for quite some time apparently (many months). This is apparently due to the issue still having with it still blowing diodes in the control box. But Richard M connected it up and we confirmed that the rotation stage works as expected. 

We then proactively decided to check out the power connection for then CO2Y laser at the table enclosure feedthrough. Turned out that it was barely connected. We tried once again trying to connect it securely and it sort of looks like it is. Then when we tried to turn the laser on, I wasnt seeing the signs that it was lasing like it should. Its very low power when look at the beam on the cards. 

We went and checked out the power supply for CO2Y and as expected for what I am seeing its drawing far less current than it should (see pic). Should be drawing about 22-24 Amps but is only drawing ~12 amps. In fact the laser is drawing less than this (more on that in a bit). So there is still a problem. Unsure if its the connector or if the laser RF driver. So as a next step Ive asked Greg to do as we did as a temporary solution at LLO and cut a big hole in a spare feedthrough so that we can make as good a connection with the laser power cables as possible and cable tie them together to make sure they dont come apart and to rule that out before swap the laser RF driver again. Note: We really need to come up with a better feedthrough solution for these lasers (I know its been low on peoples lists for awhile). 

Now back to the power supplies. Turns out my last alog about the power supply setup was slightly wrong (Greg is going to write an amendment). Turns out that an individual power supply is still powering both the CO2 laser and the AOM driver for a table. So when we "turn off" the  CO2Y laser at the MEDM screen, the laser power supply shows that it is still having 2.5Amps drawn from it. In this standby mode it should only have 0.7Amps drawn so the AOM driver is drawing 1.8Amps (this driver has not faulted).

Now I had thought that the CO2X laser and AOM supplies had been split, but I am wrong here and they are on the same supply as well. The Kepco power supply that I thought should be used for the AOM driver is being used to power the little Phoenix interlock box. This seems a waste of a Kepco DC power supply for this and like I said I thought these should be for the AOM drivers. I need to go back and look at how LLO is wired and talk to Aidan, but I do suggest that a window be found soon to bring down both TCS tables so that they can be wired up correctly. Also this would help with below problem

Now also because the laser and the AOM driver is currently coming off the same supply, because the CO2X AOM driver has faulted the way to reset this is to power toggle it. But in this current setup this also turns off the laser and I didnt want to do that to then have to allow the laser to stablise again. So CO2X is left as status quo. 

So the current situation is:

CO2x

Laser and AOM driver powered off same supply

Laser running

AOM driver faulted

Dont know about if rotation stage working (assume it is)

CO2Y

Rotation stage now working

laser and AOM driver powered off same supply

Issue with laser and current being drawn so laser turned off at the MEDM screen and at the control box and keys in key safe

Beam blocked in two locations after HWP (done on earlier visit by Alastair)

What i think we need to look at in the very near term:

Modification to feedthrough to see if can get temporarily a better connection on power cable

Connecting up TCS electronics (and this includes the phoenix interlock board) correctly

Looking at a better feedthrough arrangement that is more sturdy.