WP12.4: SRF HOM Beam Diagnostics (18 December 2013)

chaired by Roger Jones (Univ. of Manchester/CI)
Wednesday, 18 December 2013 from to (Europe/London)
at Skype
EuCARD2 Quarterly Meeting

Part of Innovative RF Technologies WP12, Task 4: SRF HOM Beam Diagnostics.

The meeting will be conducted via Skype. We will review progress and future plans to utilize HOMs to provide diagnostic information for both the main accelerating cavities and the 3rd harmonic cavities -in the cryomodules of both FLASH and XFEL.

Presentations will commence at 10:30 am (UK time), with twenty minutes for each speaker. The plan is to finish by 12:00.

Plans for future WP12.4 meetings will be discussed.

HOMSC14 is being planned at Fermi National Accelerator Laboratory, USA in July 2014. Details are expected to be announced in the near future.

Below is the official record of this task, including milestones and deliverables.
Task 12.4: SRF HOM Beam Diagnostics
The energy radiated from the HOM coupler ports allows the beam offset to be measured and the beam to be centered within the TESLA accelerating cavities and the 3.9 GHz bunch shaping cavities due to be installed at the European XFEL. It is particularly important to center the beam in the 3rd harmonic cavities, since they have a significantly larger wake-field than the main accelerating cavities. Initial HOM-based electronics for beam diagnostics for such monitors has already been developed and installed at the TESLA cavities at FLASH, DESY Hamburg. This has demonstrated operation of these HOM BPMs and in this sense has served as a proof-of-principle. Electronics for the 3.9 GHz cavities at FLASH are under design, based on experimental and theoretical studies. HOM-based electronics to facilitate measurement of beam position is also planned for the cavities at the XFEL.
The research programme will capitalize on previous experience, with both types of cavities. Several issues need to be studied: the cavities will require positioning within each module, and this is anticipated to modify the HOM spectrum. The higher bunch repetition frequency (4.5 MHz as compared to currently 1 MHz at FLASH) will increase the difficulty of multi-bunch measurements. The electronics is required to adhere to the XFEL standard and consequently will be forced to be significantly more compact than previous versions. In addition, the possibility to accurately measure the beam phase with respect to the RF phase, using monopole HOMs will be assessed.
Experimental and theoretical studies will be conducted for both FLASH and the European XFEL. The common goal will be on furthering the experimental measurement of HOMs within FLASH and XFEL. Past experience, on the 4-cavity module ACC39, indicates significant coupling of eigenmodes within successive cavities. We will study the 8-cavity module within XFEL with a view to shedding light on the coupling therein. Studies on the 1.3 GHz accelerating cavities within XFEL will also be conducted.
D12.4.1 Report on characterisation of HOMs in XFEL cryomodules  12 Task 12.4    R       PU      M48
Report on characterisation of HOMs in XFEL cryomodules: Summary report comprising complete HOM characterisation of the XFEL cryomodules comparing measurements with simulations, defining the electronics requirements for the beam position measurement system and its subsequent validation (task 12.4). [month 48]
84      Completed characterisation of HOMs in the 8-cavity XFEL 3HC module      12 (Task 12.4)  M24     Activity Report
85      Cold S¬21 measurements on XFEL modules performed        12 (Task 12.4)  M24     Activity Report
Beam-based measurements on XFEL modules performed       12 (Task 12.4)  M36     Activity Report
Completed coupled cavity simulations of 8-cavity module 12 (Task 12.4)  M36     Activity Report
Participants Nicoleta Baboi; Thomas Flisgen; Puneet Jain; Roger Jones; Liangliang Shi; Ursula van Rienen
Go to day
  • Wednesday, 18 December 2013
    • 10:30 - 10:40 Overview of HOMBPM Task 12.4 10'
      Speaker: Prof. Roger Jones (Univ. Manchester/CI)
      Material: Slides powerpoint file
    • 10:45 - 11:05 Progress and Plans for Experimental Measurements, Sub-Task 12.4.1 20'
      Speakers: Mr. liangliang shi (University of Manchester/ DESY), Dr. Nicoleta Baboi (DESY)
      Material: Slides powerpoint file
    • 11:10 - 11:30 Progress and Plans for Full-Cryomodule HOM Simulations, Sub-Task 12.4.2 20'
      Speakers: Dr. Puneet Jain (Univ. of Manchester / CI), Prof. Roger Jones (Univ. Manchester/CI)
      Material: Slides pdf file
    • 11:35 - 11:55 State Space Models for RF Structures, Sub-Task 12.4.3 20'
      Speakers: Mr. Thomas Flisgen (University of Rostock), Prof. Ursula van Rienen (University of Rostock)
      Material: Slides pdf file