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

OnOff

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-pa

ram

eter

s, d

BS-

para

met

ers,

dB

TransmissionGa

p w

idth

(mm

)

Frequency, GHz11.0 13.0

2.5

10.5

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)

Stor

ed e

nerg

y, ar

b.

I. Syratchev, HGW 2012, KEK, Japan

ReflectionTransmission

ON

OFF

Bold line – measuredThin 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 2011.

External recirculation loop

Internal recirculation

Variable reflector

Variable short circuitVariable Power splitter and Phase shifter, GYCOM (Russia).

I. Syratchev, HGW 2012, KEK, Japan

Piston tuning range

Phas

e tu

ning

Short circuit S-parameters measured at two extreme (locked) positionsFull recirculation. Reference point.

Measured isolation>20 dB

Forward

Reflected

RF phase RF 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 reflectionThe 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

1800

0FF0N

Waveform for the different reflection and fixed (1800) phase advance

Procedure: Medium (10 A) current, long (240 ns) pulseThe short circuit was set on the expected 1800 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

b

nrc N

n

tjnn

N

kb

jk eatAFFweSFFtFFwFFttU00

12 ))(()()(

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 2011. 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