presented by Elmar Vogel
ACC39 operation at FLASH
TESLA Technology Collaboration (TTC)Meeting, INFN Milan, Italy, March 2011
TTC March 2011
Elmar Vogel (DESY HH) TESLA Technology Collaboration (TTC) Meeting, INFN Milan, Italy – February 28th to March 3rd 2011
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Phase space linearization works fine
'DESY News' 21st May 2010:
TTC March 2011
Elmar Vogel (DESY HH) TESLA Technology Collaboration (TTC) Meeting, INFN Milan, Italy – February 28th to March 3rd 2011
3
Performance of the FNAL built ACC39
presently, the maximum operable sum voltage is 22 MV (ø 16.5 MV/m) restricted by interlocks...
F3A8 F3A3 F3A7 F3A50
5
10
15
20
25
grad
ient
[MV/
m]
cavity
Fermilab tests vertical horizontal start field emission
DESY tests CMTB start field emission
FLASH design value 14 MV/m
TTC March 2011
Elmar Vogel (DESY HH) TESLA Technology Collaboration (TTC) Meeting, INFN Milan, Italy – February 28th to March 3rd 2011
4
Gradient restricting interlocksswitching off the rf and the beam
TTC March 2011
Elmar Vogel (DESY HH) TESLA Technology Collaboration (TTC) Meeting, INFN Milan, Italy – February 28th to March 3rd 2011
5
ACC39 is the prototype for the XFEL 3rd harmonic system
Major points of interest for XFEL 3.9 GHz design
Effects spoiling the transverse beam emittance? coupler kicks?
transverse cavity (cell) alignment?
trapped HOMs?
HOM absorber heating due to RF operation and by beam? remember braking HOM f-parts at first built 3.9 GHz cavities
HOMs are equipped with temperature sensors and interlocks!
do we get problems at high beam currents?
TTC March 2011
Elmar Vogel (DESY HH) TESLA Technology Collaboration (TTC) Meeting, INFN Milan, Italy – February 28th to March 3rd 2011
6
No distortion of the transverse emittance due to ACC39
Comparison of transverse emittance with and without ACC39
See theses from M. Kuhn, 'Influence of the Third Harmonic Module on the Beam Size‘, Hamburg University (2010)
TTC March 2011
Elmar Vogel (DESY HH) TESLA Technology Collaboration (TTC) Meeting, INFN Milan, Italy – February 28th to March 3rd 2011
7
Former problems with broken doubleleg f-parts in HOM absorbers
Problems with doubleleg f-parts: therefore FNAL designed singleleg f-parts, also usedfor the XFEL!
TTC March 2011
Elmar Vogel (DESY HH) TESLA Technology Collaboration (TTC) Meeting, INFN Milan, Italy – February 28th to March 3rd 2011
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During FASH operation: no problems,even with high beam currents > 4 mA
high beam current and 'normal FLASH' operation
bunch number
temperature readings of HOM absorber flanges
temperature readings at HOM absorber top hat position
TTC March 2011
Elmar Vogel (DESY HH) TESLA Technology Collaboration (TTC) Meeting, INFN Milan, Italy – February 28th to March 3rd 2011
9
Conclusion: We are on the right waywith the cavity and inner module design!
picture © DESYpicture of XFEL prototype