Analysis and experiment of the hypervapotron mock-up for the EAST upgrade
During the EAST upgrade, the peak heat flux applied on the first wall components will be 2 MW/m2, which requires powerful cooling concept to decrease the component temperature, in order to simplify the material requirement and armor/heat sink module design. Hypervapotron is a promising method for high heat transfer coefficient, which bases on sub cooling boiling phenomenon, and has the potential to support the demand in several years (up to 20 MW/m2 with strong armor), and is chosen to be a candidate. The design contains a copper heat sink and uses water as coolant, a series of CFD analyses are performed to optimize the design, and a mock-up based on this optimization is assembled on a high heat flux test facility which employs electromagnetic induction heating and high speed photography; during the experiment under the required working conditions, the flowing status and thermal parameters are recorded. The analysis and experiment confirm the performance of the hypervapotron concept and the feasibility of the use in the EAST upgrade project.
Optimization of armour geometry and bonding techniques for tungsten-armoured high heat flux components
Joining of tungsten with copper-based cooling structure and armour geometry optimization are the major aspects in development of the tungsten-armoured plasma facing components (PFC). Fabrication techniques and high heat flux (HHF) tests of tungsten-armoured components have to reflect different PFC designs and acceptable manufacturing cost. The authors present the recent results of tungsten-armoured mock-ups development based on manufacturing and HHF tests. Two aspects were investigated-selection of armour geometry and examination of tungsten-copper bonding techniques. Brazing and casting tungsten-copper bonding techniques were used in small mock-ups. The mock-ups with armour tiles (20 x 5 x 10, 10 x 10 x 10, 20 x 20 x 10, 27 x 27 x 10) mm 3 in dimensions were tested by cyclic heat fluxes in the range of (5-20) MW/m 2 , the number of thermal cycles varied from hundreds to several thousands for each mock-up. The results of the tests show the applicability of different geometry and different bonding technique to corresponding heat loading. A medium-scale mock-up 0.6-m in length was manufactured and tested. HHF tests of the medium-scale mock-up have demonstrated the applicability of the applied bonding techniques and armour geometry for full-scale PFC's manufacturing.
Infrared characterization and high heat flux testing of plasma sprayed layers
Abstract Four series of plasma sprayed actively cooled mock-ups have been evaluated by infrared measurements and heat flux testing. Infrared characterization showed heat transfer capability of the plasma sprayed layer bonded to the substrate. Even if the thermal conductivity of the B 4 C plasma sprayed coating is only 5% of the bulk material, the coating can easily survive 1000 cycles at 7.5 MW/m 2 if the thickness is less than 150 μm. Thick tungsten coatings (3–5 mm) were more fragile, depending on the plasma spray technology. The highest heat flux acceptable for 1000 cycles is 4 MW/m 2 with a vacuum plasma spray coating and a Ni–Al–Si–W precoating, accounting for a reduction in the thermal conductivity by a factor of 3.