A. Lanza

Power converters for future LHC experiments

The paper describes power switching converters suitable for possible power supply distribution networks for the upgraded detectors at the High Luminosity LHC collider. The proposed topologies have been selected by considering their tolerance to the highly hostile environment where the converters will operate as well as their limited electromagnetic noise emission. The analysis focuses on the description of the power supplies for noble liquid calorimeters, such as the Atlas LAr calorimeters, though several outcomes of this research can be applied to other detectors of the future LHC experiments. Experimental results carried on demonstrators are provided.

Developments on DC/DC converters for the LHC experiment upgrades

Prototypes of DC/DC power and Point of Load (PoL) converters were designed and built with the aim of satisfying the foreseen working parameters of the High Luminosity (HL) LHC experiments, using both Silicon (Si) MOSFETs and/or more recent devices substantiated of better power performance, like Silicon Carbide (SiC) and Gallium Nitride (GaN) transistors. Optimization of their design, based on the comparison between the simulated and measured thermal, electrical and mechanical performance, is in progress, and many improvements with respect to the previous versions are under implementation. We discuss in this paper the results of the last modifications. In addition, many tens of discrete component samples, chosen among the devices commercially available in the three different technologies (Si, SiC and GaN), were electrically characterized and tested under γ-rays, neutron, proton and heavy ion radiation, also using a combined run method. We have also planned to test some commercial DC/DCs under the extreme conditions of radiation and magnetic field expected in the upgrades of the LHC experiments. Here we show the first results on few samples.

Reliability oriented design of power supplies for high energy physics applications

Abstract The paper describes the design of switching converters suitable for power supply application in the LHC proton accelerator, in operation since 2010 at the European Organization for Nuclear Research (CERN) in Geneva (Switzerland). Experiments running at LHC must reliably operate in a harsh environment, due to radiation, high magnetic fields, and stringent thermal constraints. The followed approach takes into account the very tight reliability requirements during all the design stages, from the choice of circuit topologies and radiation hard power components, to the thermal layout and material optimization. Results carried out on prototypes are reported.

Power supply distribution system for calorimeters at the LHC beyond the nominal luminosity

This paper investigates the use of switching converters for the power supply distribution to calorimeters in the ATLAS experiment when the Large Hadron Collider (LHC) will be upgraded beyond the nominal luminosity. Due to the highly hostile environment the converters must operate in, all the main aspects are considered in the investigation, from the selection of the switching converter topologies to the thermal analysis of components and PCBs, with attention to reliability issues of power devices subject to ionizing radiations. The analysis focuses on the particular, but crucial, case of the power supplies for calorimeters, though several outcomes of the research can profitably be applied to other detectors like muon chambers.

A main converter for future LHC experiments: Features measurement and reliability considerations

Devices used in future experiments at LHC will be called to work in very hostile environment. Power supply is a key aspects in this scenario and new converter will be re-designed in order to meet the future requirements. In this paper a main DC-DC power converter, developed by authors in the framework of the APOLLO R&D project, has been proposed and the experimental activity devoted to its characterization is presented and discussed.

Metrological characterization of a cold plate test bench

The reliability of a power converter can be improved using a well-dimensioned cold plate. At this aim it is necessary to realize a state of the art cold plate by means of thermal-fluid dynamic numerical analysis and ad-hoc designed experimental test bench. Features and metrological characterization of test bench for cold plate design and verification will be discussed in this paper.

Point of Load for LHC experiments: Testing the behaviour in hostile environment

Devices used in future experiments at LHC will be called to work in a very hostile environment. Power supply is a key aspect in this scenario, and new converters will be re-designed in order to meet the future requirements. Moreover, also Point of Load (PoL) converters, as circuits able to adapt the voltage level for each board, device and situation, need to be re-designed in order to meet the future specifications. In this paper, both experimental activity for verify the compliance with the hostile environment of a commercial PoL and the features of an ad- hoc designed PoL will be presented and discussed.

Radiation and magnetic field effects on new semiconductor power devices for HL-LHC experiments

The radiation hardness of commercial Silicon Carbide and Gallium Nitride power MOSFETs is presented in this paper, for Total Ionizing Dose effects and Single Event Effects, under gamma, neutrons, protons and heavy ions. Similar tests are discussed for commercial DC-DC converters, also tested in operation under magnetic field.

Metrological Characterization of Cold Plates for Power Converters

The reliability of a power converter can be improved using a well-dimensioned cold plate. For this purpose, it is necessary to realize a state-of-the-art cold plate by means of thermal-fluid dynamic numerical analysis and an ad hoc experimental test bench. Features and metrological characterization of a test bench for cold plate characterization are discussed in this paper. An infrared camera is used to measure the outer surfaces, and thermocouples are employed to measure the temperatures of some inner points, but not all the points of a structure under test are accessible to probes and sensing. An accurate 3-D numerical model has been set to widen the cold plate characterization investigating the values of the variables of interest, such as the temperature and the water velocity field, in all the points of the geometry. A case study is described, showing that using modeling with potentially high accuracy in designing new systems can be useful not only to choose, by comparison, the best solution, saving time and prototyping costs, but also to foresee the system performance.