SPLminutes19November2008 < SPL

SPL Web>SplWeb>MeetingMinutes>SPLminutes19November2008 (2008-11-20, FrankGerigk)

Minutes of the SPL working group

meeting no. 89 (draft)

date: 19. November 2008

present: P. Baudrenghien (AB/RF), O. Brunner (AB/RF), C. Carli (AB/ABP), E. Ciapala (AB/RF), C. De Almeida Martins (AB/PO), M. Eshraqi (AB/ABP), R. Garoby (AB/BI), F. Gerigk (AB/RF), K. Hanke (AB/OP), T. Hermanns (AB/OP), W. Hofle (AB/RF), J. Lollierou (AB/RF), AM. Lombardi (AB/ABP), R. Losito (AB/ATB), V. Parma (AT/MCS), M. Pasini (AB/RF), S. Peggs( BNL, AB/ABP), M. Poehler (TS/CE), C. Rossi (AB/RF), M. Schuh (AB/RF), J. Strait (FNAL, AB/CO), J. Tuckmantel (AB/RF), D. Valuch (AB/RF), M. Vretenar (AB/RF), W. Weingarten (AB/RF), R. Wegner (AB/RF)

agenda

1. General news, report from LHeC workshop (Roland Garoby)
2. LLRF developments in FP7 (Wolfgang Hofle)
3. Higher Order Modes in the SPL (Marcel Schuh)
4. AOB (all)
5. next meeting
6. linked documents in EDMS

1. General news (Roland Garoby)

RG presented the provisional planning by TS/CE for the construction of the SPL/PS2 (see below). From the planning it is clear that the civil engineering integration studies have to start in the beginning of 2009, by which date the SPL team needs to provide detailed data on space requirements and infrastructure to civil engineering (M. Poehler and LA Lopez-Hernandez). If the buildings works shall start early 2012, then the civil engineering design has to be frozen by the 3d quarter of 2010, to leave time for the preparation of the tendering documents and drawings and then to go to the tendering exercise. It is clear that this planning can only be kept if the SPL study receives more support inside of CERN.

On December 11-12, the first SPL collaboration meeting will take place. The goal is to coordinate the contributions from the different institutes and to identify areas, which are not yet covered. In this first meeting, the largest potential contributors will present their capabilities and their plans for supporting the SPL. There will be four dedicated working groups, covering SC cavities, cryo-modules, beam dynamics, and high-power RF equipment. Members of the SPL study group are encouraged to register if they are concerned.

2. LLRF developments in FP7 (Wolfgang Hofle)

WH presented

the status of the LLRF developments within FP7-CNI (Construction of New Infrastructure). Under the heading of SLHC-PP (Preparatory Phase of the LHC Upgrade), the LLRF work for the SPL takes place within work-package 7 (WP7): "Critical Components for Injectors". WP7 is led by R. Scrivens and also includes a task on the "H- source for the SPL". The LLRF work takes place under the name "field stabilisation in pulsed superconducting low-beta accelerating structures", is coordinated by CERN AB/RF/FB and has participants from CERN, CEA Saclay, and INFN Milano. Some of the milestones are the characterisation of 2 tuners developed by CEA Saclay and INFN Milano for a 5-cell beta=0.5 cavity. WH presented different possible topologies for the splitting of klystron power to 4 cavities. Three layouts will be studied: i) one with one klystron per cavity ii) one with one klystron for 4 cavities without using phase/amplitude shifters and only one circulator per klystron. Here only the piezos are used for individual adjustments of the cavities (and to avoid possible control instabilities), iii) one with phase/amplitude shifters and only one circulator protecting the klystron .

A test of LHC-type controls for the characterisation of the Saclay tuner is in preparation and should take place in the first quarter of 2009. There are still some mechanical problems regarding the integration of the INFN tuner, meaning that tests will probably take place later. So far no fast phase loop is installed in the system, but it is deemed necessary to cope with the phase change caused by the 75% drop of the RF pulse current, when the cavity is switched from the filling mode to the steady state mode without beam.

Due to the need of PPM operation, it became clear that the feed-forward system needs to use a book-keeping system in order to cope with changing pulse lengths/currents in the SPL.

3. Higher Order Modes in the SPL (Marcel Schuh)

MS presented

a study on Higher Order Modes in SPL type cavities. He calculated the HOM characteristics in SPL type cavities for 704 and 1408 MHz cavities using scaled cavity models from an existing beta=0.65 cavity and from the TESLA nine-gap cavities. These simulations were done with HFSS and Superfish and the simulation results were compared with existing cavity data. Using the SPL time structure he calculated the maximum HOM power, which is dissipated in the cavities assuming that the HOMs are lying exactly on multiples of the machine line (bunch repetition frequency of 352 MHz). For this worst case scenario he finds that the maximum Q_ex, which can be accepted for higher order modes is in the range of 10⁷. For higher values the heat load for the cryogenic system becomes too large. The next step will be to study the influence of HOMs on the beam.

4. AOB

M. Eshraqi presented a first analysis of using the SPL for the acceleration of electrons. Two scenarios were consdidered i) assume that the quadrupole fields can be tuned: it was found that beam can be injected at 35 MeV into the SPL b=0.92 section and will then gain 3.5 GeV of beam energy in one pass ii) the magnet values are assumed to be the same as for proton acceleration: Here it was found that one can inject electrons with 1.35 GeV of energy to achieve 100% transmission and an acceleration of 3.5 GeV.
F. Gerigk reported on a collaboration meeting with the Soltan Institute, which took place yesterday. see minutes.
F. Gerigk and W. Weingarten reported from a workshop in Germany to foster the collaboration of universities with large accelerator institutes (GSI, DESY, CERN). The ministry of science is willing to grant a total of 24 M¤/year for this program, with 50% foreseen for High Energy Physics and 50% for nuclear physics. The deadline for applications was set to be the 1st of December, and unfortunately the details of this program only became clear to CERN during the workshop. Several working groups were defined and W. Weingarten is coordinating the workpackage on Superconducting Cavities. Despite the short notice we will try to formulate projects that could be funded within the program.
It is planned to split future SPL meetings into general information meetings for everyone, and specific technical meetings.