High power operation with beam of a CLIC pets equipped with on/off mechanism

One of the feasibility issues of the CLIC two-beam scheme, is the possibility of rapidly switching off the rf power production in an individual Power Extraction and Transfer Structures (PETS) in case of breakdowns, either in the PETS or one of the main beam accelerating structures. The proposed solution is to use a variable external reflector connected to the PETS. When activated, this scheme allows us to gradually manipulate the rf power transfer to the accelerating structure and to reduce the rf power production in the PETS itself by a factor of 4. Recently the first operation of the Two Beam Test Stand (TBTS) PETS equipped with an ON/OFF mechanism was performed in CTF3. In this paper we will present the results of the PETS operation when powered by the drive beam up to high peak power levels (>100 MW) and compare them to expectations

X-band rf power production and deceleration in the two-beam test stand of the Compact Linear Collider test facility

We discuss X-band rf power production and deceleration in the two-beam test stand of the CLIC test facility at CERN. The rf power is extracted from an electron drive beam by a specially designed power extraction structure. In order to test the structures at high-power levels, part of the generated power is recirculated to an input port, thus allowing for increased deceleration and power levels within the structure. The degree of recirculation is controlled by a splitter and phase shifter. We present a model that describes the system and validate it with measurements over a wide range of parameters. Moreover, by correlating rf power measurements with the energy lost by the electron beam, as measured in a spectrometer placed after the power extraction structure, we are able to identify system parameters, including the form factor of the electron beam. The quality of the agreement between model and reality gives us confidence to extrapolate the results found in the present test facility towards the parameter regime of CLIC

Flashbox Compact Beam Spectometer and its Application to the High-Gradient Acceleration Study

A Flashbox compact spectrometer has been developed for the Two-beam Test Stand (TBTS), which is a part of the CLIC test facility CTF3 at CERN. It is used to study RF breakdown currents emitted from high gradient X-band accelerating structures being prototyped in the TBTS. The Flashbox is built around the beam tube such that an electron beam can pass to be accelerated in the accelerating structure while charged particles emitted from the structure can be intercepted on the spectrometer consisting of detector plates aligned along the beam axis in combination with magnetic and electric fields. The Flashbox has made it possible to identify electrons and ions emitted by the accelerating structure during RF breakdowns. We describe the Flashbox and first results