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System Considerations for Submillimeter Receiver Junji INATANI Space Utilization Research Program National Space Development 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 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 March 12 -13, Nanjing 3

Japanese Experiment Module “KIBO” SMILES March 12 -13, Nanjing 4 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 Instruments SMILES: Superconducting Submillimeter-wave Limb-emission Sounder View inside the Cryostat March 12 -13, Nanjing 5

Signal Flow March 12 -13, Nanjing 6 Signal Flow March 12 -13, Nanjing 6

640 GHz SIS Mixer 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/Al. Ox/Nb Mixer Device Fabricated at NAOJ, Nobeyama March 12 -13, Nanjing 7

Cooled HEMT Amplifiers 20 K-stage Amplifier 100 K-stage Amplifier Tphys = 300 K Vd = Cooled HEMT Amplifiers 20 K-stage Amplifier 100 K-stage Amplifier Tphys = 300 K Vd = 2 V, Id = 10 m. A Tphys = 100 K Vd = 1 V, Id = 5 m. A Tphys = 20 K Vd = 1 V, Id = 5 m. A Two HEMT Devices: FHX 76 LP Three HEMT Devices: FHX 76 LP Gain: 20 -22 d. B @300 K 23 -26 d. B @20 K March 12 -13, Nanjing Nitsuki Ltd. 28 -32 d. B @300 K 30 -33 d. B @100 K 8

Cryostat Radiation Shield: Signal Input Window: Support for 100 K Stage: Support for 20 Cryostat Radiation Shield: Signal Input Window: Support for 100 K Stage: Support for 20 K Stage: Support for 4 K Stage: March 12 -13, Nanjing MLI (40 layers) IR Filters (‘Zitex’) S 2 -GFRP Straps (12 pieces) GFRP Pipes (4 pieces) CFRP Pipes (4 pieces) 9

4 K Mechanical Cooler Cooling Capacity: 20 m. W @ 4. 5 K 200 4 K Mechanical Cooler Cooling Capacity: 20 m. W @ 4. 5 K 200 m. W @ 20 K 1000 m. W @ 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 10

Mechanical Components of Coolers Cold-head and Compressor for Two-stage Stirling Cooler Two Compressors for 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: Heat flow is reduced with two IR filters IF Thermal Design of Cryostat Window: Heat flow is reduced with two IR filters IF cables: Cu. Ni 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 Sub-mm Receiver Subsystem Cryostat AOPT Ambient Temperature Optics To Antenna To Cold-Sky Terminator AAMP Single Sideband Filter CREC He Compressor (ST) March 12 -13, Nanjing Sub-mm LO Source He Compressor (JT) 13

Acousto-Optical Spectrometer Bandwidth: 1200 MHz x 2 units IF: 1. 55 - 2. 75 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 March 12 -13, Nanjing AOS (Astrium & OPM) 14

System Considerations • • System Noise Temperature Sideband Separation Main Beam Efficiency Standing Waves 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 System Noise Temperature • Good mixer • Good IF amplifier • Low insertion loss in sub-mm optics • Tsys for SSB mode March 12 -13, Nanjing 16

Sideband Separation • Martin-Pupplet Interferometer (RF filter) – One mixer for one sideband, one 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 ü Mechanically fixed filter ü No standing waves March 12 Single Sideband Filter FSP ü Mechanically fixed filter ü No standing waves March 12 -13, Nanjing 18

SSB Balanced Mixer March 12 -13, Nanjing 19 SSB Balanced Mixer March 12 -13, Nanjing 19

Main Beam Efficiency • Low Spill-over for Main and Sub- Reflectors • Use of 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 March 12 -13, Nanjing 21 Method of Optical Image March 12 -13, Nanjing 21

Optical Image: characteristics • Wavefront is frequency independent Broad-band design • Wavefront is scaled 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 March 12 -13, Nanjing 23 Standing Waves: a simple model March 12 -13, Nanjing 23

Comparison of Three Absorbers Baselines @ 625 GHz Return Loss @ 625 GHz A. 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 Standing Waves: sensitivity limit (SMILES) March 12 -13, Nanjing 25

Expected Sensitivity March 12 -13, Nanjing 26 Expected Sensitivity March 12 -13, Nanjing 26

Accuracy of Absolute Brightness Temp. March 12 -13, Nanjing 27 Accuracy of Absolute Brightness Temp. March 12 -13, Nanjing 27

ISS Environmental Fields March 12 -13, Nanjing 28 ISS Environmental Fields March 12 -13, Nanjing 28

Cutoff Filter March 12 -13, Nanjing 29 Cutoff Filter March 12 -13, Nanjing 29

Reflection of BBH RX BBH TX @ 625 GHz A. Murk, Univ. Bern R. 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 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