GHz High Gradient Testing of a T18 TW StructureUsing a Fast Response Protection and Power Recirculating System GHz High Gradient Testing of a T18 TW Structure Using a Fast Response Protection and Power Recirculating System 1 July 2009 H AIMSON R ESEARCH C ORPORATION FG02-08ER85197 Work performed under the auspices of the U.S. Department of Energy SBIR Grant No. DE-FG02-08ER85197

2 H AIMSON R ESEARCH C ORPORATION July 2009 Objective: To Compare the High Gradient Performance of a Dual Feed T18 TW Linac Structure when Driven by a Resonant Ring Power Amplifier and when Load Terminated and Excited Directly with a High Power Klystron.

July 2009 H AIMSON R ESEARCH C ORPORATION 1.Describe Advantageous Operating Characteristics of Resonant Ring Driven TW Linacs. 2. Discuss Design Features of the Planned GHz Power Recirculating System Content: dart

2 3 P A = (1 + n)P S TEST LINAC ELECTRON SOURCE RF SOURCE RF LOAD BRIDGE BALANCE PROCESSOR SPECTROMETER RF MONITOR PSPS P F = nP S 1 4 RF BRIDGE PLPL 4 July 2009 H AIMSON R ESEARCH C ORPORATION

WITH ARC IN LINAC RF Source Power Bridge Load Power Linac Input Power Linac Reflected Power NORMAL LINAC OPERATION “Design Features and Initial RF Performance of a Gradient Hardened 17 GHz TW Linac Structure,” in Advanced Accelerator Concepts, AIP Conf. Proc., No. 1086, pp , H AIMSON R ESEARCH C ORPORATION 5 July 2009 Showing that when an Arc Occurs in the Linac, the Linac Input Power (blue) is Rapidly Truncated and, for the Remaining Portion of the Klystron RF Pulse the Bridge Input Power (red) is Automatically Directed into the Bridge Load (green). Thus, the Linac Power Amplifying Bridge Assists in Automatically Protecting both the RF Source and the High Gradient Linac Structure.

View of All-Copper 17 GHz Linac Structure and 4X Peak Power Amplifier System. 6 H AIMSON R ESEARCH C ORPORATION July 2009

H AIMSON R ESEARCH C ORPORATION 7 July 2009

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Mode Converter Used with the T18 Structure E z Field Pattern at f = MHz HRC 7131 Resonant Ring Phase Study 03/13/09 July H AIMSON R ESEARCH C ORPORATION

System Operating Frequency GHz Test Linac Attenuation Parameter (  ) Np Test Linac Harmonic Mean Group Velocity (v g ) hm c Total Loss in Feedback Loop (  ) dB Resonant Ring Transit Time ns Resonant Ring Total Phase Length deg Resonant Ring Phase Dispersion deg/MHz WR90 Rectangular Waveguide Phase/Length Relationship deg/mm Length/Phase Relationship mm/deg Design Parameters of an 11.4GHz Dual Resonant Ring System Configured for High Gradient Testing of the CLIC/KEK/SLAC (T18) Linac Structure 11 H AIMSON R ESEARCH C ORPORATION July 2009

RF Bridge Ratio [n=(T C /C) 2 ] RF Power Buildup (n+1) RF Bridge Transmission Coefficient {T C = [n(n+1)] 1/2 } RF Bridge Coupling Coefficient [C=(n+1) -1/2 ] Linac Steady-State Input Power (P A ) MW Unloaded Average Accelerating Gradient MV/m Klystron Power MW 12 H AIMSON R ESEARCH C ORPORATION July 2009

26 MW 32.5 MW 21.4 MW 13 H AIMSON R ESEARCH C ORPORATION Power Distribution to Achieve an Unloaded Accelerating Gradient of 108 MV/m An MHz Dual Resonant Ring System for High Gradient Testing CLIC/KEK/SLAC T18 Structures July 2009

-4.77 dB (1/3) Directional Coupler C. Nantista ’ MW, 1.435” height: |E s max | = ~45.6 MV/m |H s max | = ~160 kA/m ” ” ” ” r=0.0625” r=0.250” 14 July 2009

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With Adaptive Meshing M = /15/10R6 16 H AIMSON R ESEARCH C ORPORATION July 2009

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GHz High Gradient Testing of a T18 TW Structure Using a Fast Response Protection and Power Recirculating System 18 July 2009 H AIMSON R ESEARCH C ORPORATION FG02-08ER85197 Work performed under the auspices of the U.S. Department of Energy SBIR Grant No. DE-FG02-08ER85197

TRIPLE HYBRID M 17 GHz TWRK 94 CAVITY TW LINAC INJECTOR LOAD DC RFRF M PSh LOAD DC HYBRID DC 22 CAVITY TEST LINAC SPECTROMETER R F F R LOAD HYBRID W RFRF DC FRFR F R DC FC (A) (B) (b) 19 H AIMSON R ESEARCH C ORPORATION AAC2008