ACC39 operation at FLASH...'DESY News' 21st May 2010: TTC March 2011 ... FLASH design...

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

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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

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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

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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

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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