Recent Posts

21

General Discussion / BEAM PHASE MONITOR at ESRF

« Last post by Elena Buratin on November 24, 2021, 11:39:14 AM »

Hello,

At ESRF we now re-installed a high quality numeric BEAM PHASE monitor that is achieving very good & useful results.
It is based on a simple Spark-BPM electronics, using the available I and Q buffers in that device.
The resolution is about 1millidegree and it can measure at sampling speeds upto Turn-by-Turn rate (2.8us ESRF)
If you want more information please contact Elena or Kees, or download the available pdf.

22

Need help? / Strange vertical 50Hz noise in one BPM

« Last post by Laura on November 24, 2021, 11:30:26 AM »

Hello,
I am struggling with this since July: we have one BPMs that sees some strange noise only in the vertical direction. The frequency of this noise is 50 Hz.
The problem is that this BPM is in the FOFB loop and the noise is then spread around the whole sector.

We have:
- Checked and changed the associated corrector (but the noise frequency was already telling us that it was not the guilty one)
- Changed the Libera (even if the noise was only in vertical)
These modification provided no results.

Moreover this noise is not always present. We are sure that it is seen by this particular BPM since we removed corrector and BPM from the FOFB loop and we could see the noise in the vertical BPMs data even when it was out from the feedback. The other BPMs of the sector did not show anything.

I can add that this BPM is located in the middle of a standard sector (no IDs or cavities close by).
I also want to stress that this noise is observed only in the vertical direction.

Has it happens to some of you? Do you have some suggestion.

Thanks in advance,

Laura

23

General Discussion / X-BPM system in EBS

« Last post by Elena Buratin on November 04, 2021, 11:49:27 AM »

Hello,

At ESRF we finally put in operation the first two X-BPMs with very good results! Find below some information.

Two units of "optical X-BPM" were installed in October Shutdown in the Front-End modules of 2 different ending-Magnet-Source Beamlines.
These provide us with precious information on the vertical position of the X-ray beam at 23m downstream the source-point.
The concept of this type of X-BPM is 100% invasive, so not compatible with the users taking their X-ray beam when this X-BPM is inserted.
This obviously limits measurement periods of this device to 1 day per week and to moments when the users are not taking their beam.
Nevertheless, it allows us to check (regularly) with high precision if the (vertical) position of the X-ray beam is stable or not.
Both units show excellent results, and further developments on now non-invasive X-BPMs, also in BM-lines,
at the same location in the Front-End, and also only for vertical position, are on-going.

If you want more information please contact Elena or Kees, or download the available pdf here.

24

General Discussion / ICT vs Turbo-ICT

« Last post by Ewald on October 19, 2021, 10:48:27 AM »

Hello,
I was wondering if somebody has some experience with Turbo-ICTs from Bergoz:
- Anybody who uses a Turbo-ICT in the transfer line? If yes, what are the beam parameters and performances of the device?
- Any experience with direct comparison of ICT and Turbo-ICT under the same conditions?
Thank you,
Friederike

25

General Discussion / Re: BPM system in different institutes

« Last post by Benoît Roche on September 30, 2021, 04:00:58 PM »

Thank you Laura for the details of ALBA BPM system, it is now added to the beginning of this topic.

26

General Discussion / Re: BPM system in different institutes

« Last post by Laura on September 30, 2021, 03:39:11 PM »

Hello,
At ALBA we have in total 120 BPMs (Libera Brilliance) in the storage ring and we use 88 for feedback to have squared matrix, since we have 88 correctors (WEPD23 https://www.slac.stanford.edu/econf/C140914/papers/wepd23.pdf).
They are doing quite well after ~ 10 years operation but this year fans started to fail consistently and we decided to perform a full replacement campaign.
We are also testing 2 Libera Brimmiance+ and Libera Spark+Pilot-tone in some special BPMs.
In the Booster, we have 44 BPMs, 24 of them are equipped with a Libera Brilliance but we really only use 8. One BPM (the first after injection) is equipped with a Libera Spark Single pass and we use it for Linac to Booster injection efficiency measurements.
In the Linac and in the transfer lines we iindeed use Libra Spark Single Pass (Upgrade of BPMs and SRMs for the ALBA Booster to Storage Ring transfer line, DEELS 2017 https://www.synchrotron-soleil.fr/fr/evenements/deels-diagnostics-experts-european-light-sources).

27

Need help? / Re: Coupling Synchrotron Radiation into Fiber

« Last post by Johannes Steinmann on September 20, 2021, 05:34:44 PM »

Dear Kees and Ji-Gwang,

thanks much for your comments.

[...] we tried a proof-of-principle using a liquid light guide (something like: https://www.edmundoptics.com/f/liquid-light-guides/11425) at an optical table with SR since the liquid cable has a large inlet aperture, high transmission, and a large numerical aperture (for easy coupling).

This is an option we did not think about. Thanks!
We will not be able to avoid setting up a test setup in the lab. If we find something useful you will hear about it ;-)

Cheers,
Johannes

28

Need help? / Re: Coupling Synchrotron Radiation into Fiber

« Last post by Ji-Gwang Hwang on September 17, 2021, 11:56:25 AM »

 Dear Johannes

Our group had the idea to couple SR light into an optical fiber to convey the light to a fast photodiode (with an active area of 200 um^2) and we tried a proof-of-principle using a liquid light guide (something like: https://www.edmundoptics.com/f/liquid-light-guides/11425) at an optical table with SR since the liquid cable has a large inlet aperture, high transmission, and a large numerical aperture (for easy coupling).

In the test, the transmission was okay and input coupling was easy since that light guide has a large aperture.
But it is difficult to get proper outcoupling optics for the small active area. Due to the large NA, the light is quickly diverse and then it demands a lens close to the output port of the light guide. But this leads to a small magnification that causes the loss of a lot of light intensity. I guess this is the same issue for the streak camera.

 Best regards

Ji-Gwang Hwang

29

General Discussion / Re: BPM system in different institutes

« Last post by Benoît Roche on September 16, 2021, 11:00:17 AM »

Thanks Lorraine, I added your contribution to the list.

I see that you plan to upgrade the performances of your Fast Orbit Feedback quite a bit! Increasing the correction bandwidth by a factor 7 is not negligible.

It's a good time to join your team to work on this new and exciting project 

30

Need help? / Re: Coupling Synchrotron Radiation into Fiber

« Last post by Kees Scheidt on September 16, 2021, 10:34:14 AM »

Hi Johannes,
I read and understand your problem, and I think your approach of using a fiber to get the light from the tunnel
to your lab is feasible, but I have no direct experience with it. Stay in touch, and share your future experience,
it is certainly relevant.