3.9 GHz Deflecting Mode Cavity Timothy W. Koeth July 12, 2005

Table of Contents History of 3.9 DMC Cavity Simulations HOM concerns and modeling R/Q & it’s sensitivity to field flatness Wake Field Simulations Design: HOM couplers Testing: Vertical Dewar Test Results Status: ready to build !

Deflecing Mode Cavity History The Deflecting Mode Cavity (DMC) was initially planned for use in the CKM, fixed target experiment’s beam line. When chosing a frequency, a multiple of the A0 facility was chosen as to provide a means of testing the cavity. The cavity will provide a diagnostic to measure very short bunch length in the A0 Photo Injector.

Beam Line Simulations Full 3-D E-M field made for 13 cell, polarized, model was generated in HFSS – a code that uses an adaptive mesh generating algorithim. Uniformity map of the the integrated transverse kick along the the 13 cell cavity The peak magnetic field along the cavity. The electric field along axis is zero HFSS generated a flat field distribution:

Beam Line Simulations The 3-D field map was used with the ASTRA code to understand the cavity’s effect FW: 730 Femtosec 2.0 mm Resolution: 10 to 20 fsec

Lower, Same, and Higher Order Mode Concerns m = 0 modesm = 1 modes m = 2 modes not shown, but modeled. Requirement: to be maintain the DMC in “standby” in the beam line at 4.5 K. Will

Determination of R/Q Problem modes: to be filled in… Tim

LOM, SOM, HOM Couplers SAME ORDER MODE COUPLER INPUT COUPLER

LOM & HOM Couplers We are currently fine tuning the LOM and HOM coupler designs. Attempting greatest GHz rejection – stay tuned ! LOM COUPLER HOM COUPLER SOM COUPLER

Wake Field Simulations Yet to be filled in…. - TIM

Vertical Dewar Test Results Cavity design parameters 13 cells BMAX = 80 mT EMAX = 18.6 MV/m L EFF = 0.5 m P  = 5 M V/m

Horizontal Cryovessel FNAL already has a prototype horiztonal cryovessel that will host two 3.9 GHz cavities. With minor modification, we will retrofit for use in the Photo Injector Beam line. Cryogenics Feed Thermometry, LOM, SOM, & HOM power ports RF input Coupler

DMC LLRF & HLRF March 2005 Established closed loop control of Fermilab’s A0 9- cell Superconducting cavity. May 2005 Established remote control of SimCon setup at Fermilab May 2005 DESY’s remote control of 9-cell system. Closed loop remote control. Complete system calibration. Testing of Warsaw & DESY feed back algorithims Established DESY-FNAL algorithm development collaboration DESY LLRF Prep Tests at the FNPL A0PI: 1 st Display of SimCon2.1.0 closed loop control. A0, March 2005 Actual Field Amplitude Programmed Amplitude Prgrammed Phase Measured Phase Pic of 3.9 GHz Kly here

DMC Status: Ready for final design production December 2005: Cavity assemblies in construction Summer 2006: Finish cavity production Fall 2006 : Assembled cavity in cryovessel. Winter/Spring 2007:Commision with beam