Thermodynamic Modeling o f Astronomical Infrared Instruments Francesc Andre Bertomeu Hartnell College Salinas, California Research Advisor: James Larkin Research Supervisors: Michael McElwain and Shelley Wright University of California Los Angeles This project is supported by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement No. AST

Infrared Instrumentation and Applications Lt. Cmdr Geordi LaForge Military Astrophysics & Astronomy Star Trek

Importance of Cryogenics In Astronomical Infrared Instruments 1.Astronomical targets are faint. 2.Warm instruments are bright. 3.Everything above zero Kelvin emits thermal radiation (including infrared light). 4. Heat = Light. Problems Solutions 1.Cool instruments to cryogenic temperatures 2.Predict Thermodynamic behavior I.E. Thermodynamic Modeling

O.S.I.R.I.S. OH-Suppressing Infra-Red Imaging Spectrograph Designed for Keck AO system The most sensitive infrared spectrograph OSIRIS saw first light on Feb So he didn’t ticket you after running the red light? Well, he gave me a speeding ticket when I told him it was technically a blue-shifted light

O.S.I.R.I.S. Continued Consists of 1. Optics and detector 2. Dewar 3. Cooling System (Closed-Cycle Refrigerator) 4. Hydraulic lifting mechanism

O.S.I.R.I.S. Continued Consists of 1. Optics and detector 2. Dewar 3. Cooling System (Closed-Cycle Refrigerator) 4. Hydraulic lifting mechanism

O.S.I.R.I.S. Continued Consists of 1. Optics and detector 2. Dewar 3. Cooling System (Closed-Cycle Refrigerator) 4. Hydraulic lifting mechanism

The Thermal Model Simplified algorithm Q = cm # T (J) Pwr = Q/t (J/s) } Q(t) = Pwr*t Conduction = k(A/L) (T H - T C ) Radiation & Absorption = ;E AT 4 T f = (Pwr*t)/cm + T i Pwr = Net power of System 1.Calculate heat flow through conduction and radiation for each internal component 2. Determine new temperatures

The Code Written in IDL Passes in Variables Results are Plotted IDL Program

My Project 1. Update the Model to Reflect Changes 2. Adjust Parameters to fit real Data 3. Apply Finished Model to IRIS

My Project 1. Update the Model to Reflect Changes ( Radiation & Absorption = ;E AT 4 ) ( Conduction = k(A/L) (T H - T C ) ) Dewar & Shields Gold Capton Copper Strapping

My Project 1. Update the Model to Reflect Changes

My Project 2. Adjust Parameters to fit real Data

My Project 2. Adjust Parameters to fit real Data

My Project 2. Adjust Parameters to fit real Data A/L values for Copper Thermal Conductivity for Aluminum Emissivity Conduction = k(A/L) (T H - T C ) Radiation & Absorption = ;E AT 4

My Project 2. Adjust Parameters to fit real Data

Applications Applied to IRIS (design phase) 30 Meter Telescope

My Project 3. Applying Finished Model to IRIS 4 X Osiris all the way around Mass, Areas, Lengths, 4 CCR’s

Results Osiris 234 hrs to Cool 2 hr brown out = 25 hr recovery 3 hr brown out = 39 hrs recovery Iris 223 hrs to Cool 2 hr brown out = 10 hr recovery 3 hr brown out = 21 hrs recovery

Conclusion Previous model was updated to reflect changes made during construction OSIRIS Final product was be adapted to model the behavior of next generation of integral field spectrographs Program is important for predicting cryogenic behavior of cryogenic instruments.

Acknowledgements CfAO Members and Staff Research Advisor: James Larkin Research Supervisors: Michael McElwain and Shelley Wright UCLA IR Lab This project is supported by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement No. AST