Minutes of the SPL steering group

meeting no. 1

date: 26. October 2007

present: E. Ciapala, R. Garoby, F. Gerigk, A. Lombardi, R. Losito, V. Parma, C. Rossi
excused: M. Vretenar, W. Weingarten

Agenda

1. FP7 and present funding situation (R. Garoby)
2. Summary of the SRF'07 workshop in China (F. Gerigk, R. Losito)
3. Discussion on responsabilities
4. Round table
5. Actions
6. next meeting

1. FP7 and present funding situation (R. Garoby)

  • a general list of needed resources and their origin is described in resource list,
  • Rolands presentation of the FP7 bid for the construction of a SPL type cryo-module at the recent Open ESGARD meeting,
  • an overview of material resources: Rolands presentation in a recent PAF meeting
  • Wolfgangs presentation for a RF SC test stand at CERN at the ESGARD meeting,
  • FP7 status: see R. Garobys presentation at CARE'07. Altogether there are three integrated activities (IAs), each with a volume of 15 M. The purpose of the IAs is to improve existing research infrastructure in Europe. R. Garoby is heading working group 1 for "High-intensity high-energy proton beams" (WG2: novel accelerating systems, WG3: Superconducting RF accelerating systems). Within WG1 the SPL is part of a JRA on "Superconducting cavities and cryo-modules for pulsed proton linacs". Originally the idea was to have 4 JRAs, which share the expected 15 M, + 8 M for additional options. In this scheme the JRA containing the SPL cryo-module development was part of the "additional options". Now, the funds have been restricted to 15 M total. After equalizing all man-power in all JRAs to a cost of 70 k per year (some were valued at 100 k), and after re-shuffling the available funds, the "SPL-JRA" is now within the 15 M with a sum of ~1.5 M (contribution from Europe: 0.45 M). However, the originally requested part for a SPL-specific cryo-module R&D was removed in favor of increased funds for SC cavities (CEA, S. Chel). That should strengthen the work on the superconducting cavities, allowing for the construction of a beta=0.65 cavity after the beta=1 types and covering items necessary for the integration of the beta=1 cavities in the cryomodule (external parts of couplers, tuners with piezo etc.). The foreseen studies and work on beam dynamics are preserved. The development of the cryo-module still has to take place with the same planning in collaboration with other partners but outside of the IA.

2. Summary of the SRF'07 workshop in China (F. Gerigk, R. Losito)

  • The bulk of the work was concentrated on cavity development for ILC/FEL, there were some presentations on low-beta spoke cavities mostly for use in RIB facilities. There was only one presentation on low-beta SC elliptical cavities at 700 MHz by the Korean PEFP project, which is planning to extend the energy of their linac from 100 MeV up to 200 MeV or even 1 GeV depending on the upgrade scenario.
  • The present nominal gradient for the ILC is 35 MV/m to be reached in a vertical cryostat and 31.5 MV/m in operation. As comparison, XFEL has a target of 24 MV/m. During the experiments for XFEL they found no difference in gradient between pulsed (10 Hz) and CW operation. 10 cryo-modules have been built for TTF, 4 of those have the final geometry. In one module they have tested a new power distribution system where the RF system matches the power to each cavity (of one string) individually. It is planned to use this approach for XFEL.
  • The SNS cryo-system now operates at 2K because the pipe diameters no longer allow 4.5K operation (Campisi). Tt seems that there was less field emission at 4.5 K than at 2 K.
  • Theoretical work predicts maximum gradients for Nb cavities of 65 MV/m should be possible, 59 was already achieved at Cornell (single cell, H. Padamsee). Higher gradients of 120 or even 200 MV/m may be possible with Nb3Sn, MgB2.
  • There was interesting theoretical work on a RF fan-out algorithm to match the power to each cavity in a system where one klystron feeds multiple cavities (Y. Kang, SNS)
  • There were no presentations on diagnostics used to study why certain cavities do not reach high gradients. With little effort CERN could provide this service for other labs. This could be one of the strong points when negotiating for a SC RF test stand at CERN.

3. Discussion on responsibilities

The following responsibilities have been defined and accepted by all those present: R. Garoby: project leader, F. Gerigk: deputy, A. Lombardi: beam dynamics, R. Losito: SC cavity development and testing, V. Parma: cryo-module development, C. Rossi: RF system, E. Ciapala & W. Weingarten: RF test stand, M. Vretenar: consistency with Linac4. It is expected that the partitioning of the work will evolve.

4. Round table

V. Parma:

  • said the Indians are interested to develop cryo-module technology and that there may be a possibility for collaboration.
  • stressed that the ILC cryo-modules, which are considered as the basis for the SPL modules, are conceived for 3 km long cryo-strings and that it may be worth while to develop a system that is more suited for the SPL purposes,

R. Garoby:

  • encouraged everyone to revisit the basic choices that have been made for the SPL, e.g. cryogenic temperature and frequency (see action list).
  • an essential goal during the next 3 months will be to clarify the technical and intellectual resources that will contribute to the SPL study at CERN

F. Gerigk:

  • At some point next year there could be a SPL-workshop with external contributions: i) to definitively state the gradient/frequency/temperature for the SPL, ii) to discuss an R&D program, which will allow to publish a technical design report in 2011, iii) to identify possible partners.

5. Actions

Assigned to Start date Description State Result
FrankGerigk 2007-10-29 evaluate if 704 MHz is the optimum frequency and consider 1.4 GHz presentation edit

6. Next meeting

will take place on Friday, November, 9th, 2007, 16:00 in room 124-R-012

-- FrankGerigk - 26 Oct 2007

Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf Fan-out_algorithm.pdf r1 manage 238.5 K 2007-10-29 - 11:10 FrankGerigk SC RF fan-out algorithm to feed several cavities with one klystron
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Topic revision: r12 - 2008-02-07 - FrankGerigk
 
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