Exploring the Engineering Performance Limits of DNB

The DNB for ITER operates at 100 kV and has an additional attribute of modulation of beam at a frequency of 5 Hz for 3s with a 20s interval between two modulation events. The design of an injector for DNB that supports the attributes of modulation and transport have been characterised as a subject of this work. Analysis of the mechanical design of the components has been carried out by Finite Element Analysis softwareANSYS. Methodology adopted for the design consists of evaluation of heat flux incident and applying the heat flux to beam transport elements; performing heat transfer calculations and simulations with ANSYS and thus – arriving at the thermal response of the components. Once the thermal response meets the imposed thermomechanical requirements such as temperature limits, local heat flux limits etc, structural analysis by ANSYS was taken up. The thermal response and additional boundary conditions formed inputs to the structural analysis, resulting in the structural response of the components. ITER structural criteria-Structural Design Criteria for InVessel Components (SDC-IC) was used for verification in terms of M-type (Monotonic) and C-type (Cycling) material damages. After the design verification was done for mandated pulse scenario, the limits of operation have been assessed within the constraints of hydraulic flow parameters for each of the components. This assessment was basically to provide to ITER a recommendation for possible operation of the DNB beyond the mandated limits of modulation at 5 Hz for 3s to provide users of DNB a more flexible operational phase. An experimental program of a full scale beam transport line, in the Indian Test Faculty (IN-TF) shall validate the recommendation, before commissioning of the system in ITER.