System Considerations for Submillimeter Receiver Junji INATANI Space Utilization Research Program National Space Development Agency of Japan (NASDA) March 12-13, Nanjing 1
Introduction 640 GHz SIS Receiver for SMILES 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 2
March 12-13, Nanjing 3
Japanese Experiment Module KIBO SMILES March 12-13, Nanjing 4
Instruments SMILES: Superconducting Submillimeter-wave Limb-emission Sounder View inside the Cryostat March 12-13, Nanjing 5
Signal Flow March 12-13, Nanjing 6
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 7
Cooled HEMT Amplifiers 20K-stage Amplifier Two HEMT Devices: FHX76LP Gain: 20-22 db @300K 23-26 db @20K March 12-13, Nanjing 8 Nitsuki Ltd. 100K-stage Amplifier Three HEMT Devices: FHX76LP Gain: 28-32 db @300K 30-33 db @100K
Cryostat Radiation Shield: Signal Input Window: Support for 100 K Stage: Support for 20 K Stage: Support for 4 K Stage: MLI (40 layers) IR Filters ( Zitex ) S2-GFRP Straps (12 pieces) GFRP Pipes (4 pieces) CFRP Pipes (4 pieces) March 12-13, Nanjing 9
4 K Mechanical Cooler Cooling Capacity: 20 mw @ 4.5 K 200 mw @ 20 K 1000 mw @ 100 K Power Consumption: 300 W @ 120 VDC Mass: Cooler Cryostat Electronics Total 40 kg 26 kg 24 kg 90 kg Cooling to 100 K & 20 K: Two-stage Stirling Cooler Cooling to 4.5 K: Joule-Thomson Cooler March 12-13, Nanjing 10
Mechanical Components of Coolers Cold-head and Compressor for Two-stage Stirling Cooler Two Compressors for Joule-Thomson Cooler March 12-13, Nanjing 11
Thermal Design of Cryostat Window: IF cables: Heat flow is reduced with two IR filters 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 12
Sub-mm Receiver Subsystem Cryostat AOPT Ambient Temperature Optics To Antenna To Cold-Sky Terminator AAMP CREC He Compressor (ST) Single Sideband Filter He Compressor (JT) Sub-mm LO Source March 12-13, Nanjing 13
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 14
System Considerations System Noise Temperature Sideband Separation Main Beam Efficiency Standing Waves ( Gain Stability ) ( Spectral Resolution ) Electromagnetic Interference (EMI) March 12-13, Nanjing 15
System Noise Temperature Good mixer Good IF amplifier Low insertion loss in sub-mm optics Tsys for SSB mode T = T ( L 1) + LT sys amb rx T T = ( L 1) ( T + T ) sys rx amb rx ssb L s dsb Ls T = 1+ T + T Li Li sys rx ref March 12-13, Nanjing 16
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) Two mixers for two sidebands, one polarization Broad RF bandwidth: no mech. tuner necessary Poor LO coupling Phase Synthesis (Balanced mixer) Four mixers for two sidebands, one polarization Broad RF bandwidth: no mech. tuner necessary Efficient LO coupling March 12-13, Nanjing 17
Single Sideband Filter FSP: Frequency Selective Polarizer ABSORBER LO SOURCE TO COLD SKY L1 U2 FSP TO ANTENNA U1 L2 ABSORBER U1 + L1 SIS MIXER 1 ABSORBER CRYOSTAT U2 + L2 SIS MIXER 2 Mechanically fixed filter No standing waves March 12-13, Nanjing 18
SSB Balanced Mixer March 12-13, Nanjing 19
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 20
Method of Optical Image W L G 1 W L 2 = 1 2 W 1 1 2 2 = 1 = 2 R 1 R2 1 1 1 = + f L L 1 2 W R + L L R W 2 f R 2 March 12-13, Nanjing 21
Optical Image: characteristics Wavefront is frequency independent Broad-band design Wavefront is scaled from the original one High beam-efficiency March 12-13, Nanjing 22
Standing Waves: a simple model V = G T ( on) Mobs( on) + T on on a sys V = G T ( off) Mobs( off ) + T off off a sys V = G T ( hot) M hot + T hot hot a sys M M obs hot = 1+ r exp( j 2 kl ) obs obs = 1+ r exp( j 2 kl ) + r exp( j 2 kl ) obs obs Von Vo ff Ta( on) = Ta( hot) T V V hot off 2 hot [ off ] a ( ) + T ( off ) a hot 2 March 12-13, Nanjing 23
Comparison of Three Absorbers Baselines @ 625 GHz Return Loss @ 625 GHz A. Murk (Univ. Bern) & R. Wylde (TK) March 12-13, Nanjing 24
Standing Waves: sensitivity limit (SMILES) March 12-13, Nanjing 25
Expected Sensitivity March 12-13, Nanjing 26
Accuracy of Absolute Brightness Temp. March 12-13, Nanjing 27
ISS Environmental Fields March 12-13, Nanjing 28
Cutoff Filter March 12-13, Nanjing 29
Reflection of BBH RX BBH TX @ 625 GHz A. Murk, Univ. Bern R. Wylde, TK March 12-13, Nanjing 30
Conclusions 640 GHz SIS Receiver for SMILES 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 31