ON/OFF news

2 4 6 8 10 1250

40

30

20

10

0

Reflected

Transmitted

Stroke 8.0 mm

RF p

ower

, dB

Piston position (gap width), mm

ON

ON

OFF

OFF

Compact design of the high RF power variable (mechanically) reflector

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

PETS ON/OFF operation (CLIC PETS)

Power to the structure

Power extracted from the drive beam

ON OFF

Open Closed

RF measurements

Broadband high RF power variable reflector prototype

Stroke 8 mm

High power variable short circuit

Originally the reflector was designed to provide reliably the 1800 phase advance.The dynamic range was increased up to about 2200 by further movement of he piston, until the chamber resonance became a danger. +30MHz

ONOFF

PETS output

Structure input

(as predicted by computer simulation)

TBTS PETS layout with internal recirculation for testing the ON/OFF concept.

Movable RF short circuit (for tuning the resonant length)

Variable reflector (for tuning the recirculation coupling)

Variable reflector

Movable RF short circuit

The components have been installed on the PETS tank.

Chat in a corridor:Igor... ‘Roberto, why do we need to run PETS with power levels above 200 MW?’Roberto... ‘ Well, it works, so why do you ask? As well we have showed 150 M/m.’

Few words about TBTS results during the past testing period

200 400 600 800 1000

50

100

150

200

250

MW

ns

Measured RF power extraction

CLIC requirement

Peak power in the PETS

BDR in recycling loop

It did, indeed! With BDR> 0.3 when peak power was > 200 MW!

attenuator

E-bend/split

IN OUT

IN

OUT

phase shifter

E-bend/direct

Highest peak power point

Let’s look inside

attenuator

load split E-bend IN

Observations: All he stainless steel flanges show sort of breakdown erosion on the surface. The copper surfaces in attenuator (GYCOM) are seriously damaged in ALL the channels. In the phase shifter (also made by GYCOM) copper surface is pretty clean.