The Faint Intergalactic-Medium Redshifted Emission Balloon: FIREBall-2 Scientific Camera and Cooling System

• Main Author: Lingner, Nicole Renate
• Format: Others
• Published: 2017
• Online Access: https://thesis.library.caltech.edu/10303/1/Nicole%20Thesis%20June.pdf; Lingner, Nicole Renate (2017) The Faint Intergalactic-Medium Redshifted Emission Balloon: FIREBall-2 Scientific Camera and Cooling System. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9QV3JKQ. https://resolver.caltech.edu/CaltechTHESIS:06062017-165519688 <https://resolver.caltech.edu/CaltechTHESIS:06062017-165519688>

<p>The FIREBall-2 instrument provides a means of investigating both the processes responsible for building cosmic structure and the galaxies that trace it. By studying the inflow and outflow of gaseous hydrogen, we can better explain galaxy formation and evolution. Each individual galaxy lies within a dense gaseous region called the circumgalactic medium (CGM), itself surrounded by the diffuse intergalactic medium (IGM). Thin gaseous filaments connect galaxies to each other in space and time and they can be found at nodes of these filaments at the center of dark matter halos.</p> <p>This large-scale structure, called the cosmicweb, has been modeled and corroborated with absorption line studies. To understand the structure of the galaxy environment, we need to map the extremely faint emission from the CGM and these filaments.</p> <p>FIREBall-2 is a 1-meter-class, balloon-borne, UV telescope that will be launched from Texas in the fall of 2017. The instrument includes a vacuum tank, which houses an all-reflective, wide-field multislit spectrograph, guide camera, and UV optimized EMCCD sensor. The scientific camera sensor has to be operated near -110°C and is cooled with a mechanical cryocooler, which also powers a charcoal getter to maintain high vacuum during flight.</p> <p>The scientific camera includes a Printed Circuit Board (PCB), which I use as a rigid harness that holds the sensor in place. The sensor (CCD201-20 from e2v) is a delta-doped, electron-multiplying charge-coupled device (EMCCD) that has been modified to be used as a 1K x 2K (1024 x 2048 pixels) sensor. The EMCCD has been developed at the Jet Propulsion Laboratory’s Micro Devices Laboratory. I operate this next-generation UV detector (NEXUS) at 10 MHz with read-out electronics from Nüvü Camēras. Nüvü’s controller for counting photons (CCCP) was chosen to achieve extremely low detector noise by reducing clock induced charge (CIC) and it is attached to the PCB with a SAMTEC EQCD high-speed coaxial cable. To reduce dark current, the other relevant detector noise source, the EMCCD is supported by a gold-plated copper clamp and cooled with a CryoTel MT mechanical cooler (Stirling engine) from Sunpower. The CCD operating temperature is -110°C, with a required heat lift of about 7 Watts at a 30°C reject temperature. Two 10-Watt Omega heaters are used to regulate the temperature. The cryocooler will be operated at a constant input cooling power of about 70 Watts, which corresponds to 110-Watts of battery power. The cooler is mounted to the side of the vacuum tank and I have incorporated the Sunpower active vibration cancellation system (AVC) to reduce the vibrational noise. A flexible copper ribbon conducts heat from the bottom of the CCD via the solid copper clamp. The detector is operated in a vacuum of about 10^-6 Torr, initially started by a turbo pump, with the pressure then lowered and maintained by activated charcoal adsorption during flight. The flight hardware has been integrated into the flight vacuum tank and is currently undergoing testing.</p>