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Cooling water conditioning and quality control for tokamaks

Description: Designers and operators of Tokamaks and all associated water cooled, peripheral equipment, are faced with the task of providing and maintaining closed-loop, low conductivity, low impurity, cooling water systems. Most of these systems must provide large volumes of high quality cooling water at reasonable cost and comply with local and state government orders and EPA mandated national pretreatment standards and regulations. This paper discusses the DIII-D water quality requirements, the means used to obtain the necessary quality and the instrumentation used for control and monitoring. Costs to mechanically and chemically condition and maintain water quality are discussed as well as the various aspects of complying with government standards and regulations.
Date: October 1, 1995
Creator: Gootgeld, A.M.
Partner: UNT Libraries Government Documents Department

Thermal analysis and testing for DIII-D ohmic heating coil repair

Description: The DIII-D ohmic heating (OH) coil solenoid consists of two parallel windings of 48 turns each cooled by water. Each winding is made up of four parallel conductors. Desired thermal capacity of the coil is 20 MJ at a repetition rate of 10 min. One of the conductors started leaking water in July 1995. Since then, the coil has been operated at a reduced thermal load using one winding. An experiment followed by an analysis was undertaken to determine if the OH-coil could be operated at full capacity without cooling the leaking segment by relying on conduction heat transfer to the neighboring cooled conductors. The analysis took into consideration the transient energy equations, including the effect of conduction between neighboring conductors. The axial conduction was modeled in the conductor, but was ignored in the coolant. An experiment was performed on the undamaged coil winding to determine the thermal conductance between neighboring conductors. The experiment consisted of passing hot water through adjacent cooling channels of two conductors and cold water through the cooling channels of the remaining two conductors of the same winding. The flow rate, inlet and outlet temperatures from each circuit were measured during the transient. From the experimental data and analysis an average thermal conductance between the conductors was determined to be about 0.1 W/cm{sup 2}-C. Using the experimentally determined value of the thermal conductance, an analysis was performed on a coil winding consisting of one uncooled conductor and three cooled conductors. Results show that it is possible to operate the full OH-coil without cooling the damaged conductor to the desired thermal load of 20 MJ per pulse.
Date: November 1, 1997
Creator: Baxi, C.B.; Anderson, P.M. & Gootgeld, A.M.
Partner: UNT Libraries Government Documents Department

Design of the advanced divertor pump cryogenic system for DIII-D

Description: The design of the cryogenic system for the D3-D advanced divertor cryocondensation pump is presented. The advanced divertor incorporates a baffle chamber and bias ring located near the bottom of the D3-D vacuum vessel. A 50,000 l/s cryocondensation pump will be installed underneath the baffle for plasma particle exhaust. The pump consists of a liquid helium cooled tube operating at 4.3{degrees}K and a liquid nitrogen cooled radiation shield. Liquid helium is fed by forced flow through the cryopump. Compressed helium gas flowing through the high pressure side of a heat exchanger is regeneratively cooled by the two-phase helium leaving the pump. The cooled high pressure gaseous helium is than liquefied by a Joule-Thomson expansion valve. The liquid is returned to a storage dewar. The liquid nitrogen for the radiation shield is supplied by forced flow from a bulk storage system. Control of the cryogenic system is accomplished by a programmable logic controller.
Date: November 1, 1991
Creator: Schaubel, K.M.; Baxi, C.B.; Campbell, G.L.; Gootgeld, A.M.; Langhorn, A.R.; Laughon, G.J. et al.
Partner: UNT Libraries Government Documents Department

Verification test for helium panel of cryopump for DIII-D advanced divertor

Description: It is planned to install a cryogenic pump in the lower divertor portion of the D3-D tokamak with a pumping speed of 50000{ell}/s and an exhaust of 2670 Pa-{ell}/s (20 Torr-{ell}s). A coaxial counter flow configuration has been chosen for the helium panel of this cryogenic pump. This paper evaluates cooldown rates and fluid stability of this configuration. A prototypic test was performed at General Atomics (GA) to increase confidence in the design. It was concluded that the helium panel cooldown rate agreed quite well with analytical prediction and was within acceptable limits. The design flow rate proved stable and two-phase pressure drop can be predicted quite accurately. 8 refs., 5 figs., 1 tab.
Date: October 1, 1991
Creator: Baxi, C.B.; Laughon, G.J.; Langhorn, A.R.; Schaubel, K.M.; Smith, J.P.; Gootgeld, A.M. et al.
Partner: UNT Libraries Government Documents Department