2019-12-04

Foil Experiment

15:30

Partially inserted Faraday cup 1 (upstream before Dipole) occupying left half of aperture. Obtained only positive current, similar as far Run 5. Downstream Faraday cups had no signal.

Removed Faraday cup 1, with Faraday cup 2 (JB end) now also having a positive current (unlike Run 5). Turning Dipole magnet on slightly, one eventually obtains a negative current but only momentarily. It appears there is significant scraping of the beam in the transport line, with the beam veering far to the left. The first Faraday cup detects a signal even when removed outside the aperture. Faraday Cup 3 (Dipole End) is showing no signal even with the dipole magnet on. It appears the beam is not making it to the main ring. This will be further investigated by removing Faraday Cup 3 as well.

18:30

Faraday Cup 3 has been removed. There are no obvious blockages which could explain there being no beam going into the main ring. The vacuum is currently being removed to check for any blockages. It is suspected a beam monitor after the dipole magnet may have become dislodged. Additionally it is planned to install a fluoresecent screen in the dipole end, although how to physically do it is still being worked out. It is then planned to reapply the vacuum overnight.

The upstream foils used in March/April were found as well hidden beside the main ring. They have remained intact, so the currently installed foils should survive the vacuum changes.

19:30

When the vacuum was being removed, the pressure levels in the main ring increased too quickly. There are no working pressure sensors in the transport line, so it it is difficult to tell the true pressure level. It is suspected there may have been a leak near the upstream foil. A spike was seen when alcohol was applied near one of the seals. The pressure level is currently oscillating and it may take some for the alcohol to be vacuumed out of the transport line. It will be left overnight.