LDX Project Status
June 19, 2003
Ability Engineering Technology (South Holland, IL) continues with the final assembly of the floating coil cryostat. The low heat leak cryogenic feedthrough bayonets were welded to the heat exchanger tubing, completing the heat exchanger circuit. Leak check of these joints were performed successfully. After initial leak-check failures, the electrical feedthrough was redesigned and successfully installed.
The charging station vacuum cylinder and internal components was completed and received at MIT.
The cryostat, quench protection system, and the box with additional items were installed into the shipping container. On May 27 the container was delivered by truck to the transportation company in the St. Petersburg port. The transportation company with a help of Sintez prepared documentation for the Russian Custom Service. According to the information received from St. Petersburg, most of custom formalities have been completed. The container will be shipped from St. Petersburg to Antwerp and then transferred to a ship going to Boston. The full time of delivery from St. Petersburg to Boston will be about 3 weeks. The exact schedule is still not determined.
MIT has received from SINTEZ an electronic version of all charging-coil drawings. Instructions for operation and other documentations are being prepared at SINTEZ and will be send to MIT.
MIT has designed and ordered an additional vacuum pumping system for the charging-coil cryostat that will improve the cryostat vacuum during operation.
Charging coil leaving SINTEZ for St. Petersburg port.
Acceptance testing of the LDX levitation-coil, cryostat and powersupply was completed on May 22. At this time, the L-coil achievedits full rated operating current of 105 A on the first attempt. The coil's emergency discharge circuit was tested later that day. The evaluated current decay time constant for the current discharge was 2.61s, which closely matches the design time constant value of 2.6s for the dump circuit. The evaluated time constant of 3.0s for the field decay measured outside of the cryostat was slightly longer, which is indicative of eddy current generation in the coil support structure and cryostat during rapid field variations.
Tests of the frequency response of the levitation coil were conducted by application of a small amplitude (about 1 amp) AC current ripple with frequencies between 0.02 and 1 Hz. The AC heat generation at 1Hz frequency was 4 times less than expected in the coil's design. Some shielding of the fluctuating fields outside of coil, due to eddy current generation in the coil's support structure was observed. Modeling activities have begun to assess the impact that these low frequency eddy currents might have on the levitation-coil performance when it is used in the feedback loop to control floating-coil position within the vacuum chamber.
Within a few days, the coil should have warmed to above freezing, at which point it can be backfilled with nitrogen gas and prepared for installation on top of the LDX vacuum vessel.
A repair was also necessary for a damaged section of the launcher bellows and the part should be received in under two weeks. We are currently installing the final parts needed for full operation of the launcher.
The designs for in-vessel ECRH antennas and vacuum feedthroughs have been finalized. With two sources (2.45 and 6.4 GHz) for first plasma operation ready, work is proceeding to ready a third source (at 10.5 GHz) source for operation.