V. Veshcherevich Cornell University CORNELL ERL COUPLERS: 1. COUPLER FOR ERL MAIN LINAC V. Veshcherevich Cornell University June 13, 2013 TTC Workshop 2013

ERL Main Linac Cavity Each 7-cell cavity of the Cornell ERL Main Linac has one coupler June 13, 2013 TTC Workshop 2013

RF power and Qext requirements 10 6 7 8 9 2 4 RF power [W] Q L 0 Hz 10 Hz 20 Hz 30 Hz 40 Hz 7-cell cavity @16.2 MV/m RF power and Qext requirements are determined by microphonics (+ possible beam loss, beam return time errors, etc.) June 13, 2013 TTC Workshop 2013

TTF-III Coupler as Prototype The design of the ERL Main Linac coupler is based on the design of classic TTF-III input coupler June 13, 2013 TTC Workshop 2013

Parameters of ERL Main Linac Coupler Operating frequency 1.3 GHz Maximum power (CW) 5 kW Qext (fixed) 6.5×107 Cold coaxial line impedance 70 Ohm Warm coaxial line 46 Ohm Cold coax line outer diameter 40 mm Warm coax line outer 62 mm June 13, 2013 TTC Workshop 2013

Main Linac Coupler Challenges Main challenges for the linac coupler: Mechanical flexibility to accommodate large movement (> 10 mm) of cold mass inside the cryomodule during the cool down Minimizing cryogenic heat loads June 13, 2013 TTC Workshop 2013

ERL Main Linac Coupler Copper plating: 5μ Bellows Air Cooling W650 Waveguide Flange Cold Ceramic Window Instrumentation Port Pump Port 40K Flange 5K Intercept Cavity Flange (2K) Antenna Warm Ceramic Window 300K Flange Copper plating: 5μ 40K He Gas Cooling June 13, 2013 TTC Workshop 2013

Mechanical Flexibility Coupler has great flexibility for accommodating large movement (> 10 mm) of cold mass inside the cryomodule during the cool down. June 13, 2013 TTC Workshop 2013

ERL Main Linac Coupler: Main Parts Cold Coupler Air Cooling Socket Waveguide Box 5K Cooling Unit Warm Outer Conductor Warm Inner Conductor June 13, 2013 TTC Workshop 2013

Heat Load on Cryogenics Heat Load for 5 kW of RF power Static Heat Load Dynamic Heat Load Full Heat Load To 2 K 0.05 W 0.06 W 0.11 W To 5 K 0.64 W 0.32 W 0.96 W To 40 K 3.78 W 5.94 W 9.72 W June 13, 2013 TTC Workshop 2013

Coupler Test Stand Termination Cavity Ion Pump RF Power from Transmitter Coupler under Test Termination Cavity Ion Pump Support Plate June 13, 2013 TTC Workshop 2013

Coupler Performance Summary of the Main Linac coupler performance: Two couplers have been fabricated by CPI, Beverly and tested at Cornell on the test stand up to 5 kW CW. No major issues were noticed during the test. One coupler was attached to the prototype linac cavity. The cavity was successfully tested (w/o beam) with great results achieved inside the horizontal test cryomodule (HTC). Five more couplers are ordered for the Main Linac Cryomodule (MLC) Prototype. June 13, 2013 TTC Workshop 2013