High Power Density Neutron Target development at High Brilliance neutron Source project
Qi Ding1, Johannes Baggemann1, Jörg Wolters2
1Jülich Centre for Neutron Science JCNS-2, Forschungszentrum Jülich, 52425 Jülich, Germany
2Central Institute of Engineering, Electronics and Analytics (ZEA-1), Forschungszentrum Jülich, 52425 Jülich, Germany
With the ongoing decommissioning of older fission-based neutron sources in Europe and elsewhere in recent years, the available capacity on neutrons for science is declining and access is becoming critical for neutron users. Responding to this development and to provide an alternative approach to the realization of neutron facilities, the High Brilliance Neutron Source (HBS) project [1,2] has been initiated at the Jülich Centre for Neutron Science (JCNS) of the Forschungszentrum Jülich GmbH. It aims at developing a compact high-current accelerator-driven neutron source (Hi-CANS) to deliver high-brilliant neutron beams to a variety of neutron scattering instruments.
One of the key components as well as the main power-limiting factor is the target that generates free neutrons by proton induced nuclear reactions with an energy well below the spallation threshold. Since the neutron yield of nuclear reactions is quite small, this is compensated with a high proton current. However, the high proton current leads to a strong heat release inside the target. At the same time the target has to be very compact to allow the subsequent extraction of a neutron beam with a high brilliance. Overall, this leads to unique requirements of the HBS target given by a 70 MeV pulsed proton beam with a peak current of 100 mA and an average thermal power release of 100 kW inside the target with an irradiated area of 100 cm².
A solid tantalum target with a sophisticated internal microchannel water-cooling structure was developed, manufactured and successfully tested to match these requirements. The main concerns like heat dissipation capacity, blistering and high thermomechanical stresses have been consequently minimized during the development. Version 1.0 target was successfully tested in the electron beam facility JUDITH 2  with a high heat flux of 1 kW/cm2. Based on that, iterative optimization of particle transport properties with FLUKA2020 and thermal-mechanical simulations with ANSYS of version 2.0 target has been completed. Simultaneously, processing errors have been examined with computed tomography and the corresponding effects on the neutronics properties of the target have been estimated. Details of the resulting microchannel target design as well as optimization results will be presented.
 U. Rücker et al., The Jülich high-brilliance neutron source project; The European Physical Journal Plus (2016) 131
 P. Zakalek et al., High-brilliance neutron source project; Proc. HIAT'18, Lanzhou, China, 117-121 (2019)
 T. Weber et al., Improvements in electron beam monitoring and heat flux flatness at the JUDITH 2-facility; in Fusion Engineering and Design, Oct. 2015, vol. 96–97, pp. 187–191. doi: 0.1016/j.fusengdes.2014.11.014.
For details: Davide Reggiani, tel: 3024