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Highlights: [•] The heat flux on PFC tiles of 12s pulse duration and 630kA plasma current is about 0.02MW/m2. [•] When the cryopump is operated, the heat flux of CD is higher than without cryopump. [•] The more H-mode duration is long, the more heat flux on divertor is high. [Copyright &y& Elsevier]

Abstract: For neutral beam injection systems, the maintenance of a vacuum inside the injector box is essential for normal operation. Cryogenic pumping systems are often used to create and maintain this vacuum. Cryogenic pumping systems have been deployed on the neutral beam heating systems supporting the Joint European Torus. With these as a target application, the development of a condition monitoring scheme is presented. The scheme uses a residual generation approach. A bank of Kalman filters is used to estimate measured process variables. A residual evaluator is used to map residual signals onto a set of faults. Two example faults are simulated to demonstrate the response of the scheme. This paper contributes to the wider fusion development programme by demonstrating how a contemporary condition monitoring technique can be applied to a fusion support system, in order to improve its availability. [Copyright &y& Elsevier]

Highlights: [•] The developing of the NBI for ITER requires the construction of an injector prototype: MITICA. [•] The design of MITICA needs strong effort in modeling all the beamline components. [•] The evaluation of the distribution of power among these components is critical. [•] Two models were presented estimating the power load of primary beam and the secondary particles produced by the beam itself. [•] The results are presented and discussed. [Copyright &y& Elsevier]

Abstract: The common design of the cryopumps for pumping the divertor and the cryostat has been completed at ITER following more than 10 years of development including prototyping and a number of design studies. This final design, which will be validated by building a Pre-Production Cryopump, achieves a number of simplifications and is expected to solve issues identified in previous concepts. The paper will present the build to print manufacturing design of the cryopump according to European Standards. The fabrication and qualification methods will be discussed and a summary of the main manufacturing methods will be given. The design of the valve assembly and its integration in the cryopump with the valve shaft double bellows will be described in detail. [Copyright &y& Elsevier]

Highlights: [•] First closed-cycle single shot dilutor with no external connections. [•] Self-contained. [•] Convection used to pre-cool and to operate the cryopumps. [•] Tiltable up to 50° from vertical. [•] Theory developed and compared with experiment. [ABSTRACT FROM AUTHOR]

Abstract: Cold trap is a purification unit used in sodium cooled Fast Spectrum Reactors (FSRs) for maintaining the oxygen and hydrogen level in sodium within acceptable limits. It works on the principle of crystallization and precipitation of oxides and hydrides of sodium in a wire mesh, when the temperature of sodium is reduced below the saturation temperature. The sodium hydride gets accumulated in the secondary cold trap as a consequence of the continuous diffusion of hydrogen in sodium and with time the trap is fully loaded and becomes inoperable. The removal of these impurity deposits at intervals by keeping the cold trap in same location of the loop is known as in situ regeneration. After regeneration cold trap is qualified by gamma radiograph technique to ensure adequate removal of impurities before bringing the cold trap back to service in sodium for purification. The numerical results predict the impurity deposition pattern in the wire mesh region of cold trap. The mathematical model has been validated with experimental data obtained from model cold trap. This paper discusses the methodologies developed for qualification of regeneration of cold trap using radiography and image processing techniques for assessing impurity deposition before and after regeneration. [Copyright &y& Elsevier]

Abstract: A large scale helium cryogenic system is one of the key components for the EAST tokamak device for the cooling of PF and TF coils, structures, thermal shields, buslines, current leads and cryopumps. Since the cooling scheme of the EAST cryogenic system is fairly complicated, a reliable and flexible control system is required for cryogenic system. The cryogenic control system is based on DeltaV DCS which is the process control software developed by Emerson Company. The EAST cryogenic system has been in operation for four years and has been proved to be safe, stable and energy saving by the past 7 experiments. This paper describes the redundant control network, hardware configuration, software structure, auxiliary system and the new development in the future. [Copyright &y& Elsevier]

Abstract: The present article is focused on the computational investigation of a 2D axisymmetric complex geometry of a model cryopump by the Direct Simulation Monte Carlo (DSMC) method. Since the flow close to the cryopanels can be assumed free molecular due to low pressures, the capture coefficient of the cryopanels can be estimated by applying the Test Particle Monte Carlo method. Then, this information can be used as input data to the corresponding DSMC simulations. The macroscopic parameters of practical interest as the bulk velocity, the pressure and the temperature in the whole flow field have been calculated as functions of the incoming gas throughput and of the pump inlet valve position. The importance of these calculations is based on the fact that it can provide information for quantities which are not accessible for measurement during pump operation and that it can be used for prediction of the pump behavior. This paper describes a post-operational investigation of a built pump and is thought as a proof-of-principle test to include this approach in the design process of a future pump development. Finally, the presented code could be further developed and benchmarked towards the control of the final pump as installed in ITER. [Copyright &y& Elsevier]

Abstract: Large-scale customized cryogenic pumps are employed to pump the ITER torus. The high performance of this kind of non-conventional cryopumps is achieved by the cryosorption of the gas load on the charcoal-coated panels working at 4.5K. In order to avoid the direct thermal radiation, the 4.5K pumping panels are installed inside a 80K heat shielding system. In this paper, we will present the Monte Carlo simulation of the thermal radiation heat loads to the cryopanel circuit, the thermal shield circuit and the valve head when the pump is in stand-by, pumping and regeneration. The results are of great importance in the design of the ITER pre-production cryopump (PPC). [Copyright &y& Elsevier]