System Considerations for Submillimeter Receiver Junji INATANI Space Utilization Research Program National Space Development Agency of Japan (NASDA) March 12-13, Nanjing

Introduction 640 GHz SIS Receiver for SMILES System Considerations: Superconducting Submillimeter-wave Limb-emission Sounder System Considerations: System Noise Temperature Sideband Separation Main Beam Efficiency Standing Waves Gain Stability Spectral Resolution Electromagnetic Interference (EMI) March 12-13, Nanjing

March 12-13, Nanjing

Japanese Experiment Module “KIBO” SMILES March 12-13, Nanjing

View inside the Cryostat Instruments SMILES: Superconducting Submillimeter-wave Limb-emission Sounder View inside the Cryostat March 12-13, Nanjing

Signal Flow March 12-13, Nanjing

Inside the SIS Mixer Mount Developed by NASDA in-house activity. 640 GHz SIS Mixer Inside the SIS Mixer Mount Developed by NASDA in-house activity. 0.4 mm Nb/AlOx/Nb Mixer Device Fabricated at NAOJ, Nobeyama March 12-13, Nanjing

Cooled HEMT Amplifiers 20K-stage Amplifier 100K-stage　Amplifier Tphys = 300K Vd = 2V, Id = 10mA Tphys = 300K Vd = 2V, Id = 10mA Tphys = 20K Vd = 1V, Id = 5mA Tphys = 100K Vd = 1V, Id = 5mA Two HEMT Devices: FHX76LP Gain: 20-22 dB @300K 23-26 dB @20K Three HEMT Devices: FHX76LP Gain: 28-32 dB @300K 30-33 dB @100K Nitsuki Ltd. March 12-13, Nanjing

Cryostat Radiation Shield: MLI (40 layers) Signal Input Window: IR Filters (‘Zitex’) Support for 100 K Stage: S2-GFRP Straps (12 pieces) Support for 20 K Stage: GFRP Pipes (4 pieces) Support for 4 K Stage: CFRP Pipes (4 pieces) March 12-13, Nanjing

4 K Mechanical Cooler Cooling to 100 K & 20 K: Cooling Capacity: 20 mW @ 4.5 K 200 mW @ 20 K 1000 mW @ 100 K Power Consumption: 300 W @ 120 VDC Mass: Cooler 40 kg Cryostat 26 kg Electronics 24 kg Total 90 kg Cooling to 100 K & 20 K: Two-stage Stirling Cooler Cooling to 4.5 K: Joule-Thomson Cooler March 12-13, Nanjing

Mechanical Components of Coolers Cold-head and Compressor for Two-stage Stirling Cooler Two Compressors for Joule-Thomson Cooler March 12-13, Nanjing

Thermal Design of Cryostat Window: Heat flow is reduced with two IR filters IF cables: CuNi coaxial cables HEMT current: Circuit is optimized for a Starved Bias Condition JT load: Minimized by reducing the rate of GHe flow March 12-13, Nanjing

Sub-mm Receiver Subsystem To Antenna Ambient Temperature Optics AOPT Cryostat To Cold-Sky Terminator AAMP Single Sideband Filter CREC Sub-mm LO Source He Compressor (JT) He Compressor (ST) March 12-13, Nanjing

Acousto-Optical Spectrometer Bandwidth: 1200 MHz x 2 units IF: 1.55 - 2.75 GHz / unit Focal Plane: 1728-ch. CCD array x 2 units Frequency Resolution: 1.8 MHz (FWHM) Channel Separation: 0.8 MHz / ch. AD Conversion: 12-bit, 2-CCD readouts in 4.9 msec Adder Output: 16 bits x 1728 ch. x 2 units in 500 msec AOS (Astrium & OPM) March 12-13, Nanjing

System Considerations System Noise Temperature Sideband Separation Main Beam Efficiency Standing Waves ( Gain Stability ) ( Spectral Resolution ) Electromagnetic Interference (EMI) March 12-13, Nanjing

System Noise Temperature Good mixer Good IF amplifier Low insertion loss in sub-mm optics Tsys for SSB mode March 12-13, Nanjing

Sideband Separation Martin-Pupplet Interferometer (RF filter) One mixer for one sideband, one polarization Two mixers for two sidebands, one polarization Narrow RF bandwidth: mech. tunable or fixed Phase Synthesis (Single-ended mixer) Broad RF bandwidth: no mech. tuner necessary Poor LO coupling Phase Synthesis (Balanced mixer) Four mixers for two sidebands, one polarization Efficient LO coupling March 12-13, Nanjing

Single Sideband Filter FSP Mechanically fixed filter No standing waves March 12-13, Nanjing

SSB Balanced Mixer March 12-13, Nanjing

Main Beam Efficiency Low Spill-over for Main and Sub- Reflectors Use of Primary Horn’s Optical Image No electric field outside the horn’s aperture It is the case for its optical image, ideally Field distribution is independent of frequency Relation of Horn Aperture and Its Optical Image March 12-13, Nanjing

Method of Optical Image March 12-13, Nanjing

Optical Image: characteristics Wavefront is frequency independent  Broad-band design Wavefront is scaled from the original one  High beam-efficiency March 12-13, Nanjing

Standing Waves: a simple model March 12-13, Nanjing

Comparison of Three Absorbers Baselines @ 625 GHz Return Loss @ 625 GHz A. Murk (Univ. Bern) & R. Wylde (TK) March 12-13, Nanjing

Standing Waves: sensitivity limit (SMILES) March 12-13, Nanjing

Expected Sensitivity March 12-13, Nanjing

Accuracy of Absolute Brightness Temp. March 12-13, Nanjing

ISS Environmental Fields March 12-13, Nanjing

Cutoff Filter March 12-13, Nanjing

Reflection of BBH RX BBH TX @ 625 GHz A. Murk, Univ. Bern R. Wylde, TK March 12-13, Nanjing

Conclusions 640 GHz SIS Receiver for SMILES System Considerations: Superconducting Submillimeter-wave Limb-emission Sounder System Considerations: System Noise Temperature Sideband Separation Main Beam Efficiency Standing Waves Gain Stability Spectral Resolution Electromagnetic Interference (EMI) March 12-13, Nanjing