Minutes RF structure meeting 19.07.2007

F. Gerigk, S. Ramberger, M. Vretenar, R. Wegner

news & facts:

high-power test of Russian CCDTL prototype

Rolf checked the calibration of the detectors in the high power test stand and found that:

  • HP detectors should only be used as indicators, since they produce a significant amount of harmonics that might be reflected back from unmatched components (pick ups, ... ! at the frequencies of the harmonics!). As a result, the measured voltage can easily suggest a RF power level that is twice as high as the real one.

  • The red box is not suited for 352 MHz as the reflection of the defector is only -1 dB! (almost a short)

  • Yellow and grey boxes are suited for 350 MHz. The red box and the "Jean-Michel detector" could be modified to be suited for 350 MHz.

  • The precision of power measurements with yellow and grey boxes that can be achieved depends mainly on the accuracy of the measured voltage. As the power is proportional to voltage^2, an 5% error in the voltage transforms to 10% error in power (~0.4 dB). Including also the errors of the calibration (unfortunately not 0), the precision of power measurement with these RF detectors wont be better than +- 10 to 15%! If more precise measurements are needed, the only way is to connect a power meter directly to the pick up.

with the calibrated yellow detectors the following values were measured (at Linac4 duty cycle):

  • 260 kW in tank1 (the one with the power coupler)
  • 245 kW in tank2
  • the measurements will repeated using detectors with "more equal" readings,

other news:

  • following a geometric study of the position of SPL tunnel, which now starts slightly higher due to the higher position of Linac4, it was found that several tunnels are within 2 - 5 metres distance of the SPL tunnel. This distance is too small from the radiation protection point of view. Frank will verify will Simon Baird if these tunnels are still used.

  • Jean-Michel Lacroix started on the drawings for the PIMS cold model

  • Planning for the PIMS has to be prepared, action of Frank

decisions taken:

  • none

new actions

Assigned to Start date Description State Result
FrankGerigk 2005-06-19 PIMS: planning preliminary (optimistic) planning edit
SuitbertRamberger 2007-06-19 companies that can supply PMQs for the DTL CompaniesPMQs edit
FrankGerigk, RolfWegner, CarloRossi 2007-07-19 define amount and type of copper for PIMS assuming 3% coupling Copper for Linac4 edit
FrankGerigk 2007-07-19 check if tunnels with small distances to the SPL tunnel are still in use TunnelDistances edit

updated ActionListRF

minutes by Frank Gerigk

-- FrankGerigk - 24 Jul 2007

Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf Calibration_of_RF_detectors.pdf r1 manage 49.2 K 2007-07-24 - 15:43 FrankGerigk  
GIFgif PIMS_prototyping.gif r1 manage 22.1 K 2007-08-23 - 14:20 FrankGerigk  
Microsoft Word filedoc measurement_of_RF_detectors.doc r1 manage 220.0 K 2007-07-24 - 15:44 FrankGerigk  
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Topic revision: r7 - 2008-06-30 - FrankGerigk
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