Study of the HV power supply modules for the CUbesat Solar Polarimeter (CUSP)
Alessandro Lacerenza, Alda Rubini, Andrea Alimenti, Sergio Fabiani, Ettore Del Monte, Riccardo Campana, Mauro Centrone, Enrico Costa, Nicolas De Angelis, Giovanni De Cesare, Sergio Di Cosimo, Giuseppe Di Persio, Abhay Kumar, Pasqualino Loffredo, Giovanni Lombardi, Gabriele Minervini, Fabio Muleri, Paolo Romano, Emanuele Scalise, Enrico Silva, Paolo Soffitta, Davide Albanesi, Ilaria Baffo, Daniele Brienza, Valerio Campamaggiore, Giovanni Cucinella, Andrea Curatolo, Giulia de Iulis, Andrea Del Re, Vito Di Bari, Simone Di Filippo, Immacolata Donnarumma, Pierluigi Fanelli, Nicolas Gagliardi, Paolo Leonetti, Matteo Merge, Dario Modenini, Andrea Negri, Daniele Pecorella, Massimo Perelli, Alice Ponti, Francesca Sbop, Paolo Tortora, Alessandro Turchi, Valerio Vagelli, Emanuele Zaccagnino, Alessandro Zambardi, Costantino Zazza
TL;DR
This work addresses maintaining stable APD gain $G_{\mathrm{APD}}(T)$ in CUSP's CubeSat solar-polarimeter despite the absence of active thermal control and the orbital temperature range $-20^{\circ}\mathrm{C}$ to $+60^{\circ}\mathrm{C}$. It adopts precision-regulated HV DC-DC converters from the SMHV family (evaluating $V_{\mathrm{out}}$ regulation, current limiting, and ripple) as supply rails for APDs and MAPMTs, and defines a measurement bench to characterize the transfer function $V_{\mathrm{out}}=f(V_{\mathrm{ctrl}})$ and other performance metrics over representative inputs. The methodology includes a dedicated test setup with programmable control, HV measurement, oscilloscope ripple analysis, current limiting tests, temperature monitoring, and PicoLog 1012 data acquisition for real-time monitoring. The results provide a validated pathway for integrating compact, reliable HV power modules into CubeSat payloads, enabling real-time bias adjustment to stabilize detector response and ensure the reliability of hard X-ray polarization measurements in space.
Abstract
The CUbesat Solar Polarimeter (CUSP) project is a CubeSat mission orbiting the Earth aimed to measure the linear polarization of solar flares in the hard X-ray band by means of a Compton scattering polarimeter. CUSP will allow to study the magnetic reconnection and particle acceleration in the flaring magnetic structures of our star. CUSP is a project in the framework of the Alcor Program of the Italian Space Agency aimed to develop new CubeSat missions. CUSP undergoing the Phase B started in December 2024 that will last for 12 month. The Compton polarimeter of the CUSP payload performs coincidence measurements between plastic scintilaltors and GaGG(Ce) crystals to derive the polarization of X-rays. These sensors are readout by Multi Anode Photomultiplier Tubes (MAPMTs) and Avalanche Photodiodes (APDs) respectively. Both sensors need an HV power supply up to -1~kV (for the MAPMT) and +500~V (for the APD). We tested precision regulated High Voltage DC/DC Converters by HVM Technology Inc. with Sub-Miniature Case Size ($0.85''\times0.85''\times0.60''$) of the SMHV series. These modules are compact and suited for CubeSat missions.