New equipment for the COMPASS tokamak in Prague

On 10 November, 2010, two trucks from the Siberian city of Novosibirsk rolled up to the COMPASS tokamak at the Institute of Plasma Physics in Prague. The trucks unloaded box after box of high-tech components that had been shipped from the Russian Budker Institute of Nuclear Physics. A team of experienced technicians and physicists arrived from the Institute one week later. Their mission? To assemble and commission two powerful neutral beam injectors that will allow plasmas in the COMPASS tokamak to reach temperatures ten times higher than previously achievable.

 

The Budker Institute of Nuclear Physics crafts neutral beam injectors for research centres all over the world, tailored each time to in-situ requirements. For COMPASS, the neutral beam injectors have been designed to deliver up to 300 kW of power to the plasma (one hundred times greater than the power of an electric oven) through a narrow aperture of 5 cm for as long as 0.3 sec. In addition, beam modulation—where the neutral beam is switched on and off in a rapid sequence—is planned for measuring plasma characteristics, by directly comparing phenomena inherent to the plasma with phenomena induced by interaction of the injected beam and the plasma.

 

In COMPASS, two configurations will be possible. Either the neutral beam injectors will deliver parallel beams to the plasma—maximizing the heating effect—or they will inject beams in opposite directions to balance the force momentum on the plasma and keep plasma rotation very low. This flexibility considerably increases the plasma research possibilities on the COMPASS tokamak.

 

At present, without the heating beams, the COMPASS tokamak can reach plasma temperatures of several million Kelvin. With the two new neutral beam injectors, we expect to reach 50 million Kelvin—a record both for the Czech fusion research and for the COMPASS tokamak.