Minutes RF structure meeting 27.02.2009

F.Gerigk, M. Schuh, G. DeMichele, F. Grespan

CCDTL (FrankGerigk)

• material specifications to the CERN Purchase Departement, to visit the forgery in 10 days
• 1 tank composed by 2 preformed pieces flanged in the central plane (helicoflex) to avoid the e-beam welding of the cylinder with end plates

PIMS (FrankGerigk)

• discussion between M. Vretenar and DG Heuer if the Poland manufacture could be considered an "in kind contribution". Yes, at the conditions: 1) Linac4 group responsible of the job quality; 2) Soltan Institute (Poland) should accept a price 10% less than the CERN workshop estimation

DTL

• Status of the circuit model (FrancescoGrespan)
  • HFSS simulations to obtain value of the PC-DTube capacitance (=Cp) using Quasistatic Approximation method: for a 3 mm spacing Cp ~ 2-3 pF, increasing with the Drift Tube length (7-10-14 cm simulated)
  • Different PC modes give more or less the same value of Cp, as expected
  • writing of the circuit matrix as function of the DTL geometry (Gap number, PC number, PC position)
• Power coupler simulations (GiovanniDeMichele)
  • MWS simulations for the DTL Tank1 power coupler show a too long interconnecting guide (11.6cm). According to a first estimation it should be reduced by about 3cm.
  • At the moment the simulations take into account 80% of the unloaded Q, the worst case between the 2 methods applied for the calculation of the external Q and the beam loading.

HOM

• Longitudinal beam dynamics (MarcelSchuh)
  • the beam dynamic routine is running!
  • HOM effects on the beam dynamic is included
  • small modifications were needed due to E0*T changes for non synchronous particles in comparison to Joachim Tuckmantel's code.
  • Simulation with the actual SPL layout (2 sections, cavity spacing, etc.) started
  • Ask beam dynamic group for latest results of bunch jitter and bunch phase space, and source experts for charge jitter in order to have a realistic input.
• HFSS simulations:
  • Actual geometry of SPL cavities was analysed to get a list of HOM and their R/Q values (HFSS)
  • The frequency of the acc. Mode fits well with the superfish results, but not the field (no flat top field). Geometry must be ajusted in HFSS.
  • Difficult to know the real R/Q value because of the simulation symmetry planes

-- FrancescoGrespan - 27 Feb 2009