|LDX Project Status
October 15, 2003
Tests were performed to evaluate (1) the insertion of the inlet and outlet helium transfer lines, and (2) the thermal performance of the cryostat using liquid nitrogen cooling. During the liquid-nitrogen
cold-test, care was taken to avoid large differential temperatures between the cryostat and the magnet structures.
F-coil readied for testing in clean room at MIT.
The observed cooling rate was found to be close to the design estimates. The vacuum in the cryostat was measured to be between 5 and 2x10(-5) torr. Most of the cryostat outer surface temperature
was found to be close room temperature indicating a good thermal insulation between the vacuum vessel and the cold inner vessel. Two spots corresponding to the location of bottom supports were found to be about 7 K below room temperature indicating that most of the helium vessel weight was being supported by these two supports.
By monitoring the cyrostat warm-up rate, we were able to estimate the lower limit of floating-coil levitation time. These tests indicated a warm-up time of not less than 5.5 hours. It is expected that the cryogenic performance of the cryostat will improve when all the existing helium leaks are sealed.
After completing the cyrogenic tests described above, the outer surface of the cryostat was cleaned and the temporary seals, fill-line weld, and the cryostat top shell were removed. This allows the location of the leaks within the fill and transfer tubes to be determined and repaired.
The superconducting charging coil was delivered by a truck to Boston where it cleared customs on September 25. A rigging company delivered the container to MIT on September 26 and the C-coil was removed from its shipping container and installed in the LDX cell where it was inspected and prepared for installation below LDX vacuum vessel. The quench protection system and a box with various items were also delivered to MIT.
Charging coil being lowered into place in the LDX cell.
Upon arrival, we found the inner packing of the equipment was not sufficiently water proof, and the inside of the container and some of the electronic circuitry were wet. Visual inspection did not indicate any mechanical external damages of the equipment.
Presently, the cryostat has been installed on to its permanent support frame for cleaning and preparation. The vacuum space of the cryostat has been filled with nitrogen and vacuum pumping equipment has been assembled and connected to the pump-out port of the cryostat to check for vacuum tightness.
The levitation coil was installed in position on top of the vacuum vessel.
The launcher system has been tested successfully and readied for plasma operation.
The MDSplus data acquisition server computer used for all LDX experimental data was configured.
The ECRH sources that will be used for the initial sources have been installed in the test cell and the wave guides are being procured.
Electrical power service was provided to all large auxiliary systems, including the L-coil cryocooler, the helium recovery compressors, the vacuum system cryopump compressors, the ECRH sources, and the glow discharge power supply. The PLC programming for the vacuum system is currently being tested as we prepare for a machine pump down and glow discharge system test.