MAST has recently completed a successful engineering break which took place from September – November 2006. Operations began again on schedule on December 5th 2006.
During this engineering break new ‘active’ instability (TAE) coils were installed (to study damping rates of high frequency instabilities which may be driven by alpha particles in a burning plasma) and a short pulse, high power, 28GHz microwave system (to excite micro waves for non-solenoid plasma start-up studies). In addition, various minor diagnostic modifications and calibrations were carried out.
When operations resumed in December the initial focus was on tokamak conditioning and commissioning of the 28GHz microwave system and the Neutral Beam Injection (NBI) heating systems, particularly the new PINI source. Modifications to the PINI filament and arc voltage control circuits were successfully implemented, greatly improving controllability and allowing high voltage PINI conditioning to resume. Power output levels well in excess of 1MW have been rapidly achieved from the PINI. The 28GHz system has also been commissioned to high power (~ 165kW, 40ms). Reflected power levels are low and plasma formation by the injected microwaves has been successfully demonstrated. Further optimisation of microwave assisted start-up is underway. |
