Theoretical and Experimental studies on energy transfer in Couplers for Superconducting RF Cavities Nawin Juntong 20-December-2007

National Synchrotron Research Center is a research institute operating the Siam Photon Source (SPS), a 1.2 GeV synchrotron light source. Where I come from? - Photoemission Spectroscopy - X-Ray Lithography - X-ray Absorption Spectroscopy

Pictures from - Peter McIntosh, ERLP and 4GLS at Daresbury, SRF2007,Beijing (15-19 Oct 2007) and XFEL website My Work ERLP Daresbury XFEL Coupler High peak power, pulsed operation 7-cell 1.3GHz TESLA type Cornell Coupler High average power CW

-Study of specifications and performances (Thermal and RF) on a different RF coupler designs. -Use RF codes, HFSS, GdfidL and ECHO 2D,to determine EM fields properties, wakefields, wake potential, loss factors and kick factors. -Experimental Tests of Coupler Kicks on ERLP. Scope of Work Work Schedule January – February Understand cleanroom procedures and assist with the cleaning and assembly of XFEL Coupler and participate in RF testing. January – June Assess the Antenna shape and coupling effects of different Antenna designs. June 2008 – December Assessment of Coupler kicks, calculations and experiments October-December Use HFSS code calculate mode frequencies on monopole and dipole modes of TESLA type cavity. - Apply circuit model theory on this simulation.

Simulation Results TypeBand # f 0/GHz f p/GHz PaperResultsDiff. /MHz PaperResultsDiff. /MHz M D D M D M D D D M % HFSS 8.5 results comparison with Wanzenberg paper. Simulation on TESLA mid cell geometry. M=Monopole, D=Dipole

Circuit model theory Single chain Double chain Coupling between TE and TM field Only TE or TM field

HFSS 8.5Single Chain Circuit model 1stband2ndband3rdband1stband2ndband3rdband Phase diff.F(GHz) Diff(MHz)F(GHz)Diff(MHz)F(GHz)Diff(MHz) Max.Diff (%) HFSS 8.5Single Chain Circuit model 4thband5thband6thband4thband5thband6thband Phase diff.F(GHz) Diff(MHz)F(GHz)Diff(MHz)F(GHz)Diff(MHz) Max.Diff (%) Apply Circuit model Theory Monopole mode - use single chain model

HFSS 8.5 Circuit model 1st band2nd band1st band2nd band PhaseF(GHz) Diff(MHz)F(GHz)Diff(MHz) Max.Diff (%) TE TM TE Dipole mode – use double chain model

Dispersion Curves Red-Monopole Blue-Dipole

-END- Thank you