The UV LED - Villa Olmo
The UV LED - Villa Olmo
The UV LED - Villa Olmo
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RADIATION HARD <strong>UV</strong> <strong>LED</strong>’S<br />
LIGO Livingston<br />
Sasha Buchman<br />
Ke-Xun Sun<br />
Stanford University<br />
LIGO Hanford<br />
11th ICATPP Conference<br />
<strong>Villa</strong> <strong>Olmo</strong>, 5-9 October, 2009<br />
GP-B, Relativity Mission, Gravity Probe B<br />
Page LISA, 1 Laser Interferometer Space Antenna
Outline<br />
‣ <strong>The</strong> <strong>UV</strong> <strong>LED</strong><br />
‣ Charge management<br />
‣ <strong>The</strong> Relativity Mission, Gravity Probe B GP-B<br />
‣ <strong>The</strong> Laser Interferometer Space Antenna LISA<br />
‣ Laser Interferometer Gravitational-Wave Observatory LIGO<br />
‣ <strong>UV</strong> <strong>LED</strong> Lifetime and Radiation Testing<br />
‣ Lifetime Testing<br />
‣ Radiation Testing<br />
‣ Environmental Testing<br />
Page 2
<strong>UV</strong> <strong>LED</strong><br />
‣ Based on gallium nitride (GaN)<br />
‣ <strong>UV</strong> <strong>LED</strong> in TO39 packaging<br />
‣ Various other packaging<br />
‣ ~255 nm central frequency<br />
‣ 10 nm WHM<br />
<strong>UV</strong> <strong>LED</strong> fiber coupled<br />
<strong>UV</strong> <strong>LED</strong> Performance<br />
<strong>UV</strong> <strong>LED</strong> with ball lens<br />
Page 3
<strong>UV</strong> Charge Management<br />
Page 4<br />
‣ Use of <strong>UV</strong> Sources<br />
‣ Photoelectrons for charge management of test bodies (TB)<br />
‣ Photoemission from TB and its enclosure<br />
‣ Bipolar discharging using photoelectrons and bias<br />
‣ Test Bodies<br />
‣ Insulators (LIGO, VIRGO, GEO600)<br />
‣ Floating conductors (LISA, LPF, GP-B)<br />
‣ Charging Sources<br />
‣ Handling and installation<br />
‣ Pump-down or other gas flow<br />
‣ Separation of dissimilar materials<br />
‣ Cosmic radiation<br />
‣ Patch effects<br />
‣ Vacuum field emission (Field >10 7 V/m)<br />
‣ Charge Magnitude<br />
‣ Typically 1-100 pC/day<br />
‣ Typically
Sources for Charge Management I<br />
‣ Ion Sprayers / Ion Bars<br />
‣ For use in air<br />
‣ Standard for clean rooms and benches<br />
STATIC CLEAN<br />
DC Ionizer DC-ESR-C<br />
Clean room use<br />
SIMCO, Type P-Sh-N<br />
Working distance10-600 mm<br />
Voltage7000 V - AC<br />
‣ <strong>UV</strong> photoelectrons<br />
‣ For use in vacuum<br />
‣ GP-B, LISA, GEO 600<br />
GP-B: Hg <strong>UV</strong><br />
<strong>UV</strong> <strong>LED</strong><br />
Page 5
Sources for Charge Management II<br />
‣ Studies and Proposals<br />
‣For use in vacuum<br />
‣Field emission cathodes 1<br />
‣Ion & Electron guns 2<br />
‣<strong>The</strong>rmal filaments<br />
Ion Gun<br />
IGL-2101 / IGPS-1101<br />
5eV to 2000eV<br />
10eV to 1keV<br />
Spot : 1 - 20mm<br />
Field emission cathodes<br />
Electron Gun<br />
ELG-2/ EGPS-1022<br />
5eV to 2000eV<br />
1nA to 10µA<br />
Spot : 0.5 - 5mm<br />
Page 6<br />
Kimball Physics Inc.<br />
1<br />
GP-B Gyroscope Charge Control Using Field Emission Cathodes, S Buchman T. Quinn, M. Keiser and D. Gill, J. Vac. Sci. Technol. B 11, (1993)<br />
http://scitation.aip.org/getpdf/servlet/GetPDFServletfiletype=pdf&id=JVTBD9000011000002000407000001&idtype=cvips&prog=normal<br />
2<br />
Charge neutralization in vacuum for non-conducting and isolated objects using directed low-energy electron and ion beams S Buchman ,<br />
R.L.Byer, D Gill, N A Robertson, and K-X Sun, Class. Quantum Grav. 25 (2008) 035004 http://stacks.iop.org/0264-9381/25/035004
<strong>UV</strong> Lamps Lifetime<br />
<strong>UV</strong> Lamp A Intensity vs Operating Hours<br />
Normalized Discharge Rates vs Time - LAMP B, -3V Bias<br />
1500<br />
1400<br />
0.0E+00<br />
Intensity Monitor<br />
1300<br />
1200<br />
1100<br />
1000<br />
900<br />
800<br />
700<br />
600<br />
y = 1392.8e -0.0042x<br />
R 2 = 0.72<br />
0 50 100 150 200 250<br />
Operating Hours<br />
Rate (DN/min/IM count)<br />
-1.0E-03<br />
-2.0E-03<br />
-3.0E-03<br />
-4.0E-03<br />
-5.0E-03<br />
G1<br />
G2<br />
G3<br />
G4<br />
-6.0E-03<br />
0 20 40 60 80 100 120 140<br />
time (hours)<br />
<strong>UV</strong> Lamp B Intensity vs Operating Hours<br />
1100<br />
Intensity Monitor<br />
1000<br />
900<br />
800<br />
700<br />
y = 957.68e -0.0043x<br />
R 2 = 0.9776<br />
‣<strong>UV</strong> lamp intensity decay time constant<br />
~ 230 hours<br />
‣Large variability of discharge rates<br />
between gyroscopes<br />
600<br />
500<br />
0 20 40 60 80 100 120 140<br />
Operating Hours<br />
Page 7<br />
‣<strong>The</strong> GP-B Hg <strong>UV</strong> lamps met all<br />
requirements
GP-B Charge Management<br />
‣Charging Sources Ground Test/Analysis SM Results<br />
‣ Levitation < 1V test 200 – 500 mV<br />
‣ He gas spin-up < 1V test Not observed: < 10 mV<br />
‣ Cosmic radiation ~ 0.1 -1 mV/day (GEANT) 0.1 – 1 mV/day<br />
‣ Variations in cosmic radiation charging<br />
‣ Shielding: Decreasing from Gyro #1 to Gyro # 4<br />
‣ Solar flares<br />
‣Rotor charge controlled with <strong>UV</strong> excited electrons<br />
‣ 2 <strong>UV</strong> Hg lamps (254 nm line)<br />
‣ 8 <strong>UV</strong> switches<br />
‣ 2 <strong>UV</strong> fibers per gyroscope<br />
<strong>UV</strong> Lamp A<br />
<strong>UV</strong> Lamp B<br />
1 mV = 1 pC<br />
Schematic of GP-B<br />
<strong>UV</strong> architecture<br />
× 4 gyroscopes<br />
<strong>UV</strong> switch #1A<br />
<strong>UV</strong> switch #1B<br />
Gyro #1<br />
‣Continuous measurement at the 0.1 mV precision<br />
‣Control to 5 mV (meets requirement of 15 mV)<br />
Page 8
GP-B Charge Control: Discharge of G#1<br />
450mV<br />
<strong>UV</strong> Switches<br />
Gyro1 Charge (mV)<br />
70mV/hour<br />
discharge<br />
Lamp A<br />
Lamp B<br />
<strong>UV</strong> Lamp Assembly<br />
100mV<br />
0 mV<br />
Day of year, 2004<br />
Page 9<br />
Charge controlled to < 5 mV<br />
<strong>UV</strong> Electrode
<strong>UV</strong> <strong>LED</strong> Lifetime and Radiation Testing<br />
ILX Precision<br />
Current Source<br />
Computer<br />
Function<br />
Generator<br />
<strong>UV</strong> <strong>LED</strong> Lifetime Testing System<br />
(both vacuum & nitrogen tests)<br />
Modulation<br />
(1 kHz, 10% duty cycle)<br />
GPIB<br />
Amp<br />
Nitrogen/Vacuum<br />
Chambers<br />
<strong>UV</strong> <strong>LED</strong><br />
<strong>UV</strong> Photodiode<br />
Oscilloscope<br />
Signal to<br />
<strong>UV</strong> <strong>LED</strong><br />
Fast <strong>LED</strong> Driver and Photodetection PCB<br />
Signal from<br />
<strong>UV</strong> Photodiode<br />
Driving Signal<br />
Page 10
<strong>UV</strong> <strong>LED</strong> Based AC Charge Management<br />
Output<br />
fast modulated<br />
to generate<br />
electron packets<br />
Modulation<br />
of electrode<br />
phase locked<br />
for steering<br />
electrons<br />
Phase<br />
adjusted for<br />
bipolar charge<br />
management<br />
<strong>UV</strong><br />
e -<br />
e -<br />
<strong>UV</strong><br />
e -<br />
e -<br />
Page 11
Charging and Discharging<br />
of a proof mass potential of +/- 20 mV<br />
Results for AC charge transfer<br />
studies using a <strong>UV</strong> <strong>LED</strong> with<br />
observed power or ~11 µW at a<br />
center wavelength of 257.2 nm<br />
<strong>UV</strong> test facility<br />
Page 12
<strong>UV</strong> <strong>LED</strong> Lifetime in Nitrogen, 1 atm<br />
Spectral Stability After 19,800 Hours<br />
Power Stability After 20,000 Hours<br />
‣ <strong>UV</strong> <strong>LED</strong> emission spectrum<br />
‣ Spectral shift ≤ 2 nm shorter<br />
‣ <strong>UV</strong> <strong>LED</strong> power level<br />
‣ No significant power variation<br />
Page 13<br />
<strong>UV</strong> <strong>LED</strong> lifetime test in Nitrogen: > 28,000 hours (3.2 years)
<strong>UV</strong> <strong>LED</strong> Lifetime in Vacuum, 10 -7 torr<br />
Initial Spectrum<br />
Power Stability After 9,000 Hours<br />
‣ <strong>UV</strong> <strong>LED</strong> emission spectrum<br />
‣ <strong>UV</strong> <strong>LED</strong> power level<br />
‣ No significant power variation<br />
Page 14<br />
<strong>UV</strong> <strong>LED</strong> lifetime test in vacuum: > 17,500 hours (2 years)
Proton Irradiation<br />
63.8 MeV proton irradiation test<br />
‣ Test at UC Davis<br />
‣ Total fluence 2x10 12 proton/cm 2<br />
‣ > 100 years of dose at LISA orbit<br />
‣ <strong>UV</strong> <strong>LED</strong>s maintained light output<br />
‣ Spectral shape unchanged<br />
‣ Power intensity unchanged<br />
Page 15
Page 16
Proton Irradiation Setup at UC Davis<br />
Proton<br />
Accelerator<br />
Ames Chamber<br />
(removed for<br />
high flux proton<br />
irradiation)<br />
Protons<br />
63.8 MeV<br />
Alignment<br />
Aperture<br />
Bread Board<br />
Stanford<br />
Platform<br />
Optics Table<br />
Lab Jack<br />
Page 17
Radiation Qualification Test Setup<br />
Si Photodiode<br />
Protons<br />
63.8 MeV<br />
Beam current<br />
20-15,000 pA<br />
Flat Window<br />
<strong>UV</strong> <strong>LED</strong><br />
Ball Lens<br />
<strong>UV</strong> <strong>LED</strong><br />
SiC Photodiode<br />
Aluminum<br />
Shielding Block<br />
Electronics<br />
Electronics<br />
Shielding Wall (>1 m Concrete)<br />
Page 18<br />
Experimental setup (top view) for<br />
<strong>UV</strong> <strong>LED</strong> proton radiation tests.
<strong>UV</strong> <strong>LED</strong> Spectral Shift Measurements<br />
Before and After Proton Irradiation<br />
‣ <strong>UV</strong> <strong>LED</strong> 63.8 MeV proton irradiation test<br />
‣ Central wavelength 255 nm for both, no shift observed<br />
Page 19
Proton Irradiation Results<br />
<strong>UV</strong> <strong>LED</strong> + SiC Detector<br />
80 pA Run 500 pA Run 15,000 pA Run<br />
Proton Fluence Proton Fluence Proton Fluence<br />
1x10 10 p/cm 2 6.3x10 10 p/cm 2 2x10 12 p/cm 2<br />
Proton energy:<br />
‣ 59.0 MeV for 80 pA<br />
‣ 59.0 MeV for 500 pA<br />
‣ 63.8 MeV for 15,000 pA<br />
Space proton energy:<br />
2~5 MeV<br />
Total fluence: > 100 year<br />
Proton fluence in LISA orbit<br />
Page 20<br />
Reference for proton test of<br />
other <strong>LED</strong> and laser diodes:<br />
A. H. Johnston and T. F.<br />
Miyahira, “Characterization of<br />
Proton Damage in Light-<br />
Emitting Diodes”, IEEE Trans.<br />
Nuclear Science, 47 (6), 1999
Environmental Testing<br />
‣ <strong>UV</strong> <strong>LED</strong> in TO39 packaging tested at Ames Center<br />
‣ Shake: 3g + 7g random vibration in all three axes<br />
‣ Bake: thermal vac chamber -30°C~+ 60°C, including soak<br />
‣ Beam profile, spectra, V-I-P curves staged measurements<br />
‣ Preliminary conclusion: PASS<br />
Fiber coupled <strong>UV</strong> <strong>LED</strong><br />
<strong>UV</strong> <strong>LED</strong> mounted for testing<br />
Page 21
<strong>The</strong> Shake & Bake Setup at NASA Ames<br />
Z-direction shake test platform<br />
Bake Chamber<br />
x, y - direction shake test platform<br />
<strong>UV</strong> <strong>LED</strong><br />
SMA<br />
Packaging<br />
Grating &<br />
Mount<br />
Page 22<br />
<strong>UV</strong> <strong>LED</strong><br />
TOS39<br />
Packaging
Shake & Bake Results<br />
Beam<br />
Profile<br />
Spectrum<br />
V-I-P<br />
Curves<br />
Page 23<br />
Before test After shake After shake & bake
<strong>UV</strong> <strong>LED</strong>’s for LISA & LIGO Charge Control<br />
‣ Long lifetime >28,000 hours to date<br />
‣ Radiation hard<br />
‣ Lower power consumption<br />
‣ Lower mass<br />
‣ AC modulation up to 1 GHz<br />
<strong>UV</strong> <strong>LED</strong> Performance<br />
<strong>UV</strong> <strong>LED</strong><br />
Page 24
NASA- Stanford<br />
Gravity Reference NanoSatellites<br />
1 pm/Hz 1/2 Grating Cavity<br />
Displacement Sensor<br />
Towards ultra high precision gravitation reference<br />
sensors and multi vehicle space interferometry<br />
256 nm Deep <strong>UV</strong> <strong>LED</strong> Roundest sphere and drag<br />
free sensor<br />
1 nrad/Hz 1/2 grating<br />
angular sensor<br />
<strong>The</strong> Program<br />
Frequent launches on ride-along platforms<br />
Standard low cost bus configurations<br />
12 - 24 month project duration<br />
<strong>The</strong> Benefits<br />
New science: Physical, Life, Engineering<br />
Critical technology demonstrations<br />
Fast advance of NASA mission objectives<br />
Train engineers & scientists for the future<br />
STANFORD<br />
NANOSAT<br />
AMES<br />
GENESAT<br />
‣NASA-Ames provides nanosatellite<br />
Platform, payload integration, and mission<br />
operations<br />
Technologies<br />
Roadmap<br />
2007 2008 2009 2010 2011<br />
<strong>UV</strong> Diode<br />
Grating & Laser<br />
Grating Displacement<br />
Grating Interferometer<br />
Other Instruments<br />
Tech. Integration<br />
‣Stanford provides gravitational reference<br />
technologies<br />
Platforms<br />
Caging Mechanism Drag Free Flight<br />
Other Capabilities<br />
Micro/Nanothrusters<br />
Formation Flying<br />
3U Cubesat<br />
6U Cubesat<br />
‣About one mission per year beginning in<br />
2011<br />
‣Estimated total cost per mission is $3-5M<br />
Page 25<br />
Falcon 1<br />
Launch Opportunities<br />
GeneBox ; Flown 16 July 2006<br />
GeneSat-1; Flown 16 Dec 2006<br />
Pharmasat-1; Launch 10 Dec 2007<br />
Minotaur I<br />
Atlas V<br />
Minotaur IV<br />
Microsatellite Sorties<br />
Microsatellite Constellation<br />
2Q 08 1Q 09 3Q 09 1Q 10 4Q 10 2Q 11 4Q 11<br />
Overarching Goal: Provide Rewarding, Focused Objectives<br />
for the Next Generation of Space Scientists and Technologists
<strong>The</strong> First Planned Project<br />
<strong>UV</strong> <strong>LED</strong> Space Demonstration 2009-2011<br />
‣Charge management for high precision GRS<br />
‣Calibration source for <strong>UV</strong> and X-ray telescope<br />
‣Telescope surface and window de-charging<br />
‣Life maintaining system for space flight<br />
Nick Leindecker<br />
Payload Functional Components<br />
GENESAT<br />
Page 26<br />
<strong>UV</strong> <strong>LED</strong> Performance<br />
<strong>UV</strong> <strong>LED</strong>
<strong>UV</strong> <strong>LED</strong> Testing to Date<br />
Lifetime Test<br />
‣Lifetime test in N 2<br />
> 28,000 hours<br />
‣Llifetime test in<br />
vacuum: >17,500<br />
hours<br />
‣<strong>The</strong> spectra in N 2<br />
shifted to shorter<br />
wavelength ~2 nm<br />
Radiation Test<br />
‣63.8 MeV proton irradiation<br />
test<br />
‣Output power maintained<br />
for total fluence 2x10 12<br />
proton/cm 2 (>100 yr LISA )<br />
‣Spectral shape and power<br />
intensity unchanged after<br />
proton irradiation<br />
Shake & Bake<br />
‣Shake test 3g + 7g<br />
random vibration in<br />
all three axes<br />
‣Bake: thermal vac<br />
chamber -30°C~+<br />
60°C, +soak<br />
‣Spectral shape and<br />
power unchanged<br />
1) <strong>LED</strong> deep <strong>UV</strong> source for charge management of gravitational reference sensors, Ke-Xun Sun, B. Allard, S. Buchman, S. Williams, and R. L. Byer<br />
Class. Quantum Grav. 23 (2006) S141–S150 http://stacks.iop.org/0264-9381/23/S141<br />
2) <strong>UV</strong> <strong>LED</strong> Space Qualification, Ke-Xun Sun, N. Leindecker, S. Higuchi, S. Buchman, R. L. Byer, J. Goebel, M. McKelvey, R. McMurray, Draft in refereeing<br />
Page 27
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