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