System Considerations for Submillimeter Receiver

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1 System Considerations for Submillimeter Receiver Junji INATANI Space Utilization Research Program National Space Development Agency of Japan (NASDA) March 12-13, Nanjing 1

2 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

3 March 12-13, Nanjing 3

4 Japanese Experiment Module KIBO SMILES March 12-13, Nanjing 4

5 Instruments SMILES: Superconducting Submillimeter-wave Limb-emission Sounder View inside the Cryostat March 12-13, Nanjing 5

6 Signal Flow March 12-13, Nanjing 6

7 640 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

8 Cooled HEMT Amplifiers 20K-stage Amplifier Two HEMT Devices: FHX76LP Gain: March 12-13, Nanjing 8 Nitsuki Ltd. 100K-stage Amplifier Three HEMT Devices: FHX76LP Gain:

9 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

10 4 K Mechanical Cooler Cooling Capacity: K K K Power Consumption: 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

11 Mechanical Components of Coolers Cold-head and Compressor for Two-stage Stirling Cooler Two Compressors for Joule-Thomson Cooler March 12-13, Nanjing 11

12 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

13 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.

8 MHz (FWHM) Channel Separation: 0.8 MHz / ch.

14 Acousto-Optical Spectrometer Bandwidth: 1200 MHz x 2 units IF: 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

15 System Considerations System Noise Temperature Sideband Separation Main Beam Efficiency Standing Waves ( Gain Stability ) ( Spectral Resolution ) Electromagnetic Interference (EMI) March 12-13, Nanjing 15

16 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

17 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

18 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

19 SSB Balanced Mixer March 12-13, Nanjing 19

20 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

21 Method of Optical Image W L G 1 W L 2 = 1 2 W = 1 = 2 R 1 R = + f L L 1 2 W R + L L R W 2 f R 2 March 12-13, Nanjing 21

22 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

23 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 @

24 Comparison of Three Absorbers 625 GHz Return 625 GHz A. Murk (Univ. Bern) & R. Wylde (TK) March 12-13, Nanjing 24

25 Standing Waves: sensitivity limit (SMILES) March 12-13, Nanjing 25

26 Expected Sensitivity March 12-13, Nanjing 26

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

28 ISS Environmental Fields March 12-13, Nanjing 28

29 Cutoff Filter March 12-13, Nanjing 29

30 Reflection of BBH RX BBH 625 GHz A. Murk, Univ. Bern R. Wylde, TK March 12-13, Nanjing 30

31 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

Characterization of Various Quasi-Optical Components for the Submillimeter Limb-Sounder SMILES

Characterization of Various Quasi-Optical Components for the Submillimeter Limb-Sounder SMILES A. Murk, N. Kämpfer, R. Wylde, J. Inatani, T. Manabe and M. Seta E-mail: axel.murk@mw.iap.unibe.ch University