05.05.2015

 

Cavities for accelerator ring SIS100

FAIR “heart” under construction


3D study of an SIS100 accelerator station: The cavities will be three meters long, about 1.7 meters high and around 1.2 meters deep. (Graphic: RI Research Instruments GmbH)

FAIR GmbH recently commissioned the German-Swiss consortium comprising RI Research Instruments GmbH, Bergisch Gladbach, Germany, and Ampegon AG, Turgi, Switzerland, with the construction of 14 cavities for the accelerator ring SIS100. The two bidders, who already have extensive experience in cavity construction with linear accelerators, HF amplifiers and in power supply unit construction, asserted themselves in the tendering procedure. The acceptance of the first cavity is planned for the beginning of next year.

 

RI is building the cavities in Bergisch Gladbach on the basis of the technical planning and specification of GSI Helmholtzzentrum für Schwerionenforschung GmbH and is in charge of the development process. Together the 14 cavities literally form the “heart” of the future ring accelerator SIS100: these components create an accelerator voltage as high as 280,000 volts. This corresponds to ten times the voltage of the existing GSI facility. Ampegon will build the tetrode power amplifiers, which supply the cavities with powerful high-frequency signals, at a German subsidiary in Dortmund. The operating frequency will be between 1100 kHz and 3200 kHz. Depending upon what type of particles scientists are using for their experiments the cycle time is between one and ten seconds – the “heartbeat” behind acceleration.

 

Particles close to the speed of light

 

Prior to the acceleration of the particles in the synchrotron the ion beam is compressed to specific lengths using pulses (the bunch), which can be accelerated in the high-frequency field. The particles can be accelerated to such an extent that they orbit the accelerator ring more than 276,000 times a second. This corresponds to about 99.95 per cent of the speed of light.
In order to be able to experiment with the ion beam it is necessary for many experiments to nullify this pulse structure – to “debunch” it. To this end RI is already building the debuncher cavities for the collector ring (CR), likewise with Ampegon PPT, a subsidiary of Switzerland’s Ampegon.

 

The first of series is expected at the beginning of 2016 and will be tested at GSI. “We are very confident as the cooperation to date has been extremely good. RI is a very diligent company when it comes to implementing the requirements of the specification,” emphasizes Dr. Hans Günter König, the responsible work package leader at GSI, the project manager for the FAIR accelerator facilities. As soon as the tests have been concluded and positively evaluated by experts, the series production can begin. All the other cavities then have to pass the Factory Acceptance Test (FAT). Following delivery and completion, the series devices will be installed and tested at the proposed site – in the accelerator therefore.




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