Carbon Nanotube Flat Plate Blackbody Calibrator

Transcription

1 Carbon Nanotube Flat Plate Blackbody Calibrator John Fleming, Sandra Collins, Beth Kelsic, David Osterman, Nathan Schwartz, Bevan Staple 33 rd Space Symposium 3 April 2017 Page 1

2 Outline CNT Properties Key features Reflectance & Bi-directional reflectance distribution function (BRDF) Environmental tests Ball development of CNT blackbodies IRAD Ball investment in technology since 2010 CRAD government funded efforts since 2014 to take a high emissivity high conductance surface and make a blackbody InVEST CIRiS project launch in 2018 Developing growth on aluminum for stray light control Page 2

3 Carbon Nanotubes are Unique from all other Forms of Carbon Vertically Aligned Carbon Nanotubes (VACNTs) are hollow cylinders of sp2 bonded carbon 10s of nm diameter, 100s of µm length, >10 10 CNTs/cm 2 density Vertically aligned CNTs (VACNTs) Optimal Substrate and Growth Parameters Determined Page 3

4 BRDF (/sr) Emissivity of CNT Surface Measured by NIST Highly emissive and Lambertian surface in the IR NIST measurement uncertainty ±10-4 Reflectance measurements in IR are difficult due to noise floor of typical instruments BRDF at 3.39 um 1.E-02 GN12_1_2 5AOI GN12_1_2 30AOI 1.E-03 GN12_1_2 60AOI 1.E-04 Typical Instrument FOV 1.E Scatter Angle Relative to Surface Normal (degrees) Emissivity and BRDF comparable to cavity blackbodies Page 4

5 Total Reflectance (%) Post Processing Reduces Reflectance 0.45 VACNT Surface - Change in Reflectance After Post Processing Before (dashed) After (solid) SN-T51 After SN-T81 After SN-T87 After SN-T51 Before SN-T81 Before SN-T87 Before Note: measurements cover nm Wavelength (nm) Page 5

6 No Visual Change or Measurable BRDF change after Thermal Cycling Demonstrates Survivability BRDF at 3.39 µm BRDF at 3.39 µm Before After BRDF remained unchanged after thermal cycling (-30 C to 50 C) Page 6

7 Vibration Testing Shows Almost No Particulates Results from all CNT vibration tests < Level 280 (often much less) Tested CNTs from multiple vendors All particulates found are counted even though they are not all CNTs Vibration in 2 axes at 14.1 Grms (GEVS) and 43.8 Grms Typical particle counts for Martin Black > Level 300 Typical particle counts for Ball IR Black (JWST) = Level 300 Page 7

8 No Change in Visible Reflectance Due to Radiation Exposure Exposure equivalent to 5 years in a 700 km sun-synchronous orbit Page 8

9 Total Reflectance (%) Atomic Oxygen Exposure Exposure to high levels of AO with UV exposure completely removed coating Use in LEO on an exposed surface not recommended Blackbodies rarely exposed to high AO Sample exposed to thermal AO flux (0.03eV) no UV, total fluence 3E21 atoms/cm2 shown at right Exposure slightly reduced reflectance Sample exposed to thermal AO flux (0.03eV) no VUV, total fluence 3E21 atoms/cm2 Dashed lines are before exposure Solid lines are after exposure SN160315SIC_T2 Measurement-1 SN160315SIC_T2 Measurement-2 T2 Measurement-1 T2 Measurement Wavelength (nm) Page 9

10 Compact Infrared Radiometer in Space (CIRiS) to Validate CNT Blackbody ESTO InVEST-15 (In-space Validation of Earth Science Technologies) program to validate microbolometer detector arrays and CNT blackbodies BESST (Ball Experimental Sea Surface Temperature) airborne LWIR three channel radiometer modified for a CubeSat Delivery late 2017 Expect Launch in 2018 Fold mirror CNT blackbody Telescope Space Nadir CNT blackbody Page 10

11 CIRiS Blackbody Based on Laboratory Breadboard General Requirements for the CIRiS calibrator Performance Metric Flat Plate CNT BB Requirements Spectral Range 9 14 µm Breadboard calibrator Carbon Nanotube surface Temperature Range K Emissivity Weight (kg) < 1 Time to change temperature 2 K/min (heating) Time to stabilize Seconds Uniformity at 330K 230 mk Temperature accuracy 200 mk Heater cables PRT cables Page 11

12 Breadboard CNT Blackbody Tested From 297 K to 350 K in Ambient Laboratory Environment Temperature Rate of Change for Heating is > 2 K/min 4 minutes to reach stability of 5 mk Temperature Uniformity between 3 PRTs is < 200 mk Page 12

13 CRAD Test to Date Working with government customer to build and test blackbody assemblies Tiled four 3 x 3 VACNT coupons into single 6 x 6 blackbody Tested in vacuum from 250 to 450K System showed promise, but non-uniformity above 350K was unacceptably high Temperature and emissivity uniformity were likely causes 250K ΔT=0.25K 350K ΔT=0.35K 450K ΔT=1.1K Page 13

14 Next Phase of CRAD Build two 5 diameter VACNT blackbodies Test in vacuum over K Observe with flight quality digital 3-5 µm FPA Use source select mirror to compare collects of the two VACNT blackbodies to a NIST calibrated GSE blackbody Testing planned for summer and fall 2017 CNT BB2 SSM CNT BB1 GSE BB Page 14

15 CNTs are an Enabling Technology CNT blackbodies are highly emissive and Lambertian Survive relative environments (thermal, vibration, radiation, and lower levels of atomic oxygen) Breadboard calibrator performance demonstrated Thermal vacuum tests are ongoing CNT blackbodies are an integral part of the INVEST CIRiS project Page 15

16 Thanks to a LARGE Cast of Characters Neil Doughty Holden Chase Nathan Meister Richard Jetley Laura Kruger Jerry Valentine Matt Gross Shane Brown Zongying Wei Jordan Marks Gary Mills Ray Rehberg Lindon Lewis Joe Krehbiel Glenn Taudien Steven Harford Robert Warden Jerry Boynton Carol Dunn Valaree VanDyken Laura Coyle Keith Spargo Diane Fear Robert Johansson Kevin Weed Kim Kish Allan Sword Tim Valle Richard Gonzales Paul Hauser Joe Sprengard and Jae Hak Kim at General Nano Page 16

17 The Contributors Include Ball Internal Research and Development General Nano JPL SBIR sponsorship Nanolab NASA Earth Science Technology Office (ESTO) InVEST-15 NIST Physical Measurement Laboratory Page 17