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| Pisces Upgrade - Beam Tube Fabrication |
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| Pisces Upgrade - Beam Tube Fabrication |
These beam tubes are fabricated from type 304 stainless steel components. The fabricator is Kemco, Inc., St. Louis, MO, under subcontract to McDonnell Douglas Corporation. There are two beam tubes, one at each end of the plasma column. Their main purpose is to provide a vacuum environment for the plasma and to absorb the radiant energy from the plasma column. The 7.5-inch inner diameter of the containment tubes is larger than the plasma column; therefore, there is minimal impingement of the plasma on the surface of the tubes.
The bumper limiter is another water-cooled component that is installed in the beam line, like the beam tubes. Its function is to physically control the diameter of the plasma column to the same diameter as the exit of the anode. Hence, it will experience significant surface heating due to the impingement of the plasma on the surface of the limiter. This part is manufactured by General Atomics under contract to McDonnell Douglas Corporation.
The figure below shows the completed target-end beam tube. It is the longer of the two beam tubes and has four inlet and four outlet coolant hoses. The coolant is introduced into a common manifold block that distributes the coolant. The tube assembly consists of two concentric tubes welded together. The inner tube is thicker and has circumferential coolant channels cut into its outer surface. The outer tube is thinner and forms the outer coolant boundary. High pressure water enters the inlet and is distributed by the manifold to the coolant channels between the two concentric tubes. The coolant flow divides and flows in both directions to the outlet manifold on the opposite side of the tube.
The smaller reflecting-end beam tube is shown below. This tube is constructed and cooled in the same manner as the target-end beam tube, but only one set of inlet and outlet coolant hoses is required.
The bumper limiter is located on the target-end of the beam line, between the exit of the anode and the target-end beam tube. The surface heating of the limiter surface in contact with the plasma is expected to be up to 15 MW/m2. A circumferential coolant arrangement was used on this bumper limiter. Due to the higher heat load, a copper inner wall and two sets of inlet and outlet coolant circuits were used. The semi-circular inner wall which forms the bumper limiter surface is shown in the following picture. The inner diameter is 3.54 inches (9 cm), which corresponds to the plasma column diameter.
Another view of the bumper limiter shows one of the coolant inlet or outlet connections. This picture also illustrates the repair work to correct a warped mating surface. The surface was built up using plasma spraying of additional metal to allow the surface to be re-machined to the proper specifications. The surface for the mating O-ring was machined below the plasma coating to assure proper sealing of the O-ring. The associated O-ring minor diameter was increased to accommodate the new mating surface.
You may return to the PISCES Upgrade home page for more information or go directly to pages that illustrate the fabrication status of other PISCES Upgrade hardware:
The McDonnell Douglas Program Manager for the PISCES Upgrade design and fabrication contract is Lester M. Waganer. The University of California - San Diego is the sponsoring agency for the Department of Energy.