I. Syratchev, HGW 2012, KEK, Japan The high power demonstration of the PETS ON/OFF operation with beam. I. Syratchev for CLIC team

I. Syratchev, HGW 2012, KEK, Japan Some history…

I. Syratchev, HGW 2012, KEK, Japan Back in 2003 we have looked into many different scenarios of the local RF power production termination… …and developed the very special one with modification of the PETS impedance

I. Syratchev, HGW 2012, KEK, Japan In 2008, with changing the CLIC frequency, the different options with destructive recirculation were reconsidered and special RF components were developed… PETS power production On Off On Off Tuneable splitter with rotating section External recirculation Internal recirculation Variable reflector #1

I. Syratchev, HGW 2012, KEK, Japan ON OFF Compact design of the high RF power variable reflector #2 (2010) Radiation through the chokes The variable reflector is a core element of the PETS ON/OFF mechanism. It is activated when the local termination of the RF power production in PETS is required. S-parameters, dB Transmission Gap width (mm) Frequency, GHz

I. Syratchev, HGW 2012, KEK, Japan PETS ON/OFF operation (CLIC PETS) Power to the structure Power extracted from the drive beam ON OFF Full model analysis (GDFIDL + HFSS) “Closed” circuit RF phase was tuned using HFSS simulations with beam. /2 at 12 GHz (WR90) Extra length of the WR90 straight section, mm /4 (working point) Stored energy, arb.

I. Syratchev, HGW 2012, KEK, Japan Reflection Transmission ON OFF Bold line – measured Thin line -HFSS The variable RF reflector. The variable RF short circuit

I. Syratchev, HGW 2012, KEK, Japan Modification of the TBTS PETS tank layout in External recirculation loop Internal recirculation Variable reflector Variable short circuit Variable Power splitter and Phase shifter, GYCOM (Russia).

I. Syratchev, HGW 2012, KEK, Japan Piston tuning range Phase tuning Short circuit S-parameters measured at two extreme (locked) positions Full recirculation. Reference point. Measured isolation>20 dB Forward Reflected RF phaseRF power Reference (“0”) phase position Reflector is set on full reflection Procedure:  Low (3A) current, short (200 ns) pulse  Reflector was set on the full reflection  The short circuit position was tuned to provide highest peak power and flat RF phase both for the forward and the reflected pulses.

I. Syratchev, HGW 2012, KEK, Japan FF 0N Waveform for the different reflection and fixed (180 0 ) phase advance Procedure:  Medium (10 A) current, long (240 ns) pulse  The short circuit was set on the expected phase advance position.  The variable reflector position was change from full transmission to the full reflection. 0N 0FF Summarized by Alexey Dubrovskiy To the accelerating structure Combination x 4 In the PETS 0N 0FF 0N 0FF

I. Syratchev, HGW 2012, KEK, Japan PETS single bunch response (GDFIDL) Measured transfer spectra of the recycling loop Artificial RF phase delay for tuning Number of round trips The complete system single bunch response and spectrum Multi-bunch part Number of bunches PETS with recirculation modeling and analysis OFF case RESULT 0N OFF case OFF OFF case Measured current pulse

I. Syratchev, HGW 2012, KEK, Japan On power (simulated/measured) OFF power (measured) OFF power (simulated) PETS output, forward Simulation vs. experiment Spectra comparison

I. Syratchev, HGW 2012, KEK, Japan TBTS PETS processing history in Amplification regime.

I. Syratchev, HGW 2012, KEK, Japan TBTS PETS processing results. Generated pulse shapes

I. Syratchev, HGW 2012, KEK, Japan The PETS ON/OFF capability was successfully demonstrated in experiments with drive beam in CTF3. Currently it is used to provide RF power for the two- beam experiments in TBTS