LDX Project Status

November 8, 1999

Helium Vessel

Based on tests with the sample elbows, Ability Engineering has finalized the welding procedure for the manufacture of the Inconel 625 helium vessel. The procedure has six steps:

  1. 8 half elbows are spot welded to support plates and annealed,
  2. a special fixture is used to firmly clamp the half elbows during the inner welds,
  3. the half-elbows are paired, trimmed, and welded together,
  4. the half-elbow welds are x-ray inspected,
  5. the free-ends of the welded pairs are trimmed to the proper length according to shrinkage allowances, and
  6. the final welds are made and x-rayed to form the two half-tori.

At the present time, all of the elbow halves have been annealed and properly trimmed on one end. Two half elbows have been welded together, and they are now awaiting x-ray examination.

Floating Coil Cryostat

Ability solicited additional quotations from companies capable of spinning the outer vacuum shell because those responding to the initial RFQ could not maintain the necessary tolerances. New quotes have been received from two manufacturers. The lowest and most experienced bidder was Kosempel Mfg., which gave a preliminary quote as: $3500 tooling and 4 pieces at $1000 each. The final set of drawings were sent to Kosempel Mfg. with a request for two sets of shells (4 pieces). One set will be used to make a cryostat model to test the launcher/catcher (see below). Fabrication of the outer vacuum shell will begin when the final quote is received. Ability has continued the design and proto-typing of reinforced shield models. Models were build with spot welded wire reinforcements and copper plated Monel screen, cold welded at both sides to lead plates. The models still need some additional reinforcement for the reliable application at the LDX cryostat working conditions.

In order to assist this proto-typing effort, we have built fiberglass and epoxy shield models (as used a boat building technology) which encase the lead and copper shield material. These models were built on a straight cylinder mold and gave promising results.

Floating Coil Conductor

A soldering repair procedure had been developed and tested to effectively remove the cable ripples from the LDX F-coil conductor. These large amplitude ripples had previously been identified as the source of significant (~50%) reduction in the conductor's critical superconducting properties. The repair procedure was applied to a length of the prototype F-coil conductor initially containing ripples with amplitudes up to 0.5 mm above the nominal conductor thickness of 2.01mm. Critical current test results at BNL for this repaired conductor sample show 10~15% reduction in critical current compared to the best results that were obtained for an unrippled conductor sample. At this level of critical current, the conductor performance is within the design margin expected for the production conductor. Gauging equipment was also been developed for in-process monitoring the conductor thickness. A thickness gauging and repair procedure has been developed for the production, F-coil conductor. These procedures began at Everson Electric's manufacturing facility on Nov. 4, 1999. During this repair process, the F-coil conductor will be transferred to a second "take-up" spool so that the most heavily rippled section of the conductor will be placed in the low field regions of the completed F-coil. An initial estimate of the conductor repair time has been set at roughly two weeks.

Floating Coil Protection

The design copper protection rings that facilitate quench propagation was finalized after model joints of the ring were tested. Instructions for the joint and copper ring design and for the soldering technology was sent to Everson Electric and will be used in the manufacturing of the F-coil.

Vacuum Vessel

(see special report for more pictures)

The LDX vacuum vessel was successfully pumped down and leak checked last month. No observable leak was found during the leak checking of all welds and port seals after calibrating the leak detector which was sensitive to leak rates < 1x10-9 std cc/sec. The vessel reached a pressure of 7.5 x 10-8 Torr without baking and with only the 1000 l/s turbo pump connected. The residual gases were primarily water vapor. We have accepted the vessel from VTA/Dynavac and have approved final payments. Since completion of the vessel acceptance test, work has continued on the vacuum system. Installation of automated control has begun and the o-ring pumping system has been installed. The permanent vessel roughing system has been installed and tested. Work has begun on installation of the cryopumps and isolation gatevalves. They cryopump compressors have been serviced and charged and the coldheads and gatevalves are now being serviced.


The conceptual design review for the Launcher/Catcher was held at MIT on Sept. 21. Bob Ellis and Phil Heitzenroeder were on hand from PPPL to present the work that Bob has done on the launcher. The design entails a center rod that passes through the floating coil and two wheels that are attached to this rod that limit the motion of coil along the rod. The review was a success, and Bob is now working towards a preliminary design.

Webmaster: D. Garnier
Last updated: Tue, Apr 25, 2000