The 3MV Dust Accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies

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1 The 3MV Dust Accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies Anthony Shu University of Colorado Colorado Center for Lunar Dust and Atmospheric Studies CIPS Seminar April 22 nd, /22/2011 1

2 Outline Why a dust accelerator? Goals of the CCLDAS accelerator Couple of projects that require dust accelerator Examples of possible use by other users The CCLDAS Dust Facility How the accelerator works Performance of the dust accelerator Current and future work 4/22/2011 2

3 Why a dust accelerator? It s not just a vacuum cleaner run in reverse 4/22/2011 4

4 Goals of CCLDAS Accelerator Instrument development for lunar and interplanetary/interstellar dust What is the composition of impact-generated vapor (molecular and/or elemental)? Does the composition of vapor depend on impact energy or soil grain size distribution? What is the angular/energy distribution of vapor? What is the angular/velocity distribution of particulate debris? User Facility - for any imaginable use 4/22/2011 5

5 Dust Accelerators in the World A. Max Planck Institut fur Kernphysik, Heidelberg, Germany B. Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, CO, USA 4/22/2011 6

6 Lunar Environment 4/22/2011 7

7 Evidence of Dust on the Moon Horizon Glow LEAM Excess Solar Brightness 4/22/2011 8

8 LDEX 4/22/2011 9

Polyvinylidene Fluoride detectors http://www.

9 Polyvinylidene Fluoride detectors plastics/pvdf.html Used on New Horizons as dust detector Light weight and low power Fast recovery time allows high density measurements 4/22/

Materials Testing Space Shuttle Window damage from Micrometeorite Light Gas

htm Hypervelocity impacts can cause significant damage High speeds make most

http://www.nasa.gov/centers/wstf/laboratories /hypervelocity/gasguns.

10 Materials Testing Space Shuttle Window damage from Micrometeorite Light Gas gun impact on Glass Hypervelocity impacts can cause significant damage High speeds make most materials appear liquid Reduce efficiency of reflectors and solar cells /hypervelocity/gasguns.html Hubble Telescope Solar Panel 4/22/

equivalence principle Reflectivity allows return of 1 photon out of 10 17

11 Lunar Retro-reflectors Findings: Moon is spiraling away at 38 mm/yr Liquid core 20% of moons radius G is very stable, variation of 1 in Verification of strong equivalence principle Reflectivity allows return of 1 photon out of y/apollo/lrrr.html (Samples courtesy of D. Currie) 4/22/

Impact Light Flashes Intensity correlated to particle and target parameters THz detection can allow better specificity in material detection Characterize

12 Impact Light Flashes Intensity correlated to particle and target parameters THz detection can allow better specificity in material detection Characterize time-dependent behavior of radiating debris Can be used to look at secondary ejecta 4/22/

13 Impact Generated Plasmas Mobilize small areas generating impact craters Generate transient impact plasma cloud Expand and possibly enhance secondary ejecta yield 4/22/

14 Interstellar and Interplanetary Dust 4/22/

15 Dust Telescope DTS Signals Amplitude H (1) C (12) C 2 (24) Ni (58,60) Ag (107,109) Mass [amu] Dust mass, velocity vector and chemical, and isotopic composition M/DM > 200 4/22/

Aerogel Sample Returns http://newscenter.lbl.

16 Aerogel Sample Returns stories/2005/08/05/it came fromouter space/ Aerogel may alter chemical composition, size, and shape Can experimentally test what happens to dust particle and aerogel due to dust impacts 4/22/

17 Micrometeorite Impact Studies /22/

spectrum Reduction in reflectivity Depth of absorption bands are reduced

18 Space Weathering Space weathering from solar wind, cosmic rays, and micrometeorites Effects found on moon, Mercury, asteroids Reddening of reflected spectrum Reduction in reflectivity Depth of absorption bands are reduced ons/justice_space_weather.ppt 4/22/

com/conferences/psi2010/files/talks/tuesday/sessi

19 Dust in Fusion Devices Dust in DIII D penetration port on%206/psi19_presentation_smirnov.pdf Titanium dust in Alcator C Mod waveguide 4/22/

Operational issues tritium retention impairment of diagnostic instruments plasma

20 Dust Issues in Fusion Devices Dust Sparks in LHD Safety issues risk of explosion in Loss of Vacuum Accident, Loss of Coolant Accident events radiological hazard chemical toxicity Operational issues tritium retention impairment of diagnostic instruments plasma contamination Li dust in NSTX R.D. Smirnov, 19 th Conference on Plasma Surface Interactions 4/22/

Edge Localized Modes mitigation studies Sample of DIII D wall tile

21 Dust Injection in Fusion Devices Aims of dust injections Calibration of diagnostics Benchmark modeling of dust dynamics Testing of wall materials Edge Localized Modes mitigation studies Sample of DIII D wall tile material for dust impact studies at CCLDAS (Courtesy of D. Rudakov) 4/22/

22 The CCLDAS Dust Facility Capabilities and future work 4/22/

23 Target Chamber SF6 Tanks Beamline Overview 3MV Pelletron Pelletron 3 MV Electrostatic Generator Particle velocities: 100 km/s Active selection of particles (charge/velocity) Particle materials: Fe, Ag, Latex,??? Particle sizes: m 4/22/

24 Dust Head Pre accelerator for Pelletron Particle charging to surface electric fields of ~3x10 9 V/m (~ 30% of field emission limit) Needle kept at 20kV DC Reservoir pulsed from 20kV to Ground Extraction plate held at ground Fires particles at random rate 4/22/

and charging system More stable voltage difference maintained No belt dust

25 Pelletron Charging System E Field Similar to Van der Graaf generator Metal pellets form chain instead of band No contact between chain and charging system More stable voltage difference maintained No belt dust creation No ultimate terminal potential limit Systems up to 25MV 4/22/

Detector Passive Detection Detect image charge induced on cylinder 20 cm detector 2 200

26 Detector Passive Detection Detect image charge induced on cylinder 20 cm detector s square pulse (SNR 2.5) Smallest and fastest particles can be lost in noise 4/22/

27 Detector Signal - Good 4/22/

28 Full Beam Line Signal 4/22/

29 Comparison to Heidelberg 4/22/

30 Comparison to Heidelberg 4/22/

turbo Maglev turbo for vibration isolation Cryo pump for fast pumping Beamline port Capable of

31 Lunar Environment Impact Lab High Intensity UV UV Lamp Solar Wind Simulator Port Lamps 1 A/cm 2 9W of UV emission Sheath scale length ~5cm 14UV lamp ports Solar wind simulation port Maglev turbo Maglev turbo for vibration isolation Cryo pump for fast pumping Beamline port Capable of simulating lunar environment Vacuum pressures down to 10 6 torr Cryo Pump UV Lamp ports 4/22/

for impact generated plasma and neutrals detection Inside of UHV

32 Ultra-High Vacuum Chamber Arrived at lab, still needs to be unpacked and sealed Vacuum tested to 10 9 torr, hoping for < torr Used for impact generated plasma and neutrals detection Inside of UHV Chamber Mount Points Lid Lifting points Beamline ports Feet 4/22/

Particle Selection Unit Uses Ortec TAC/SCA to calculate timing Uses Ortec SCA to calculate pulse height Determines appropriate delay for any speed of particle High speed clock (~10MHz)

33 Particle Selection Unit Uses Ortec TAC/SCA to calculate timing Uses Ortec SCA to calculate pulse height Determines appropriate delay for any speed of particle High speed clock (~10MHz) for counting up between two pulses Low speed delay clock (variable) for counting down to determine delay Ratio of clock frequencies determines distance:l " = l $ & '( & )( 4/22/

34 Real-Time Filtering Signal embedded in noise can be extracted through cross correlation. Known signal shape allows precise choice of filter shape Maximum of correlation directly proportional to pulse height and width Threshold detection of central peak and timing from zero crossing to next signal zero crossing gives velocity Charge can be derived 4/22/

35 SIMION Modeling Red equi potential lines are spaced every 10kV Electrostatic Potential X Z Using SIMION to model beam line characteristics Modeling Dust head pre accelerator, Einzel focusing lens, and Pelletron Accelerator 4/22/

128in +20kV Ground Einzel focusing lens is turned off Red lines are equi potential lines Blue

36 Pre-acceleration with No Focusing Dust Reservoir Extraction Plate Einzel Lens (off) Pelletron Entrance 3.128in +20kV Ground Einzel focusing lens is turned off Red lines are equi potential lines Blue lines are trajectories of dust particles 75kV Dust is modeled as a point source fired in a 30 o cone from tip of needle in dust reservoir Charge to Mass Ratio is ~17 C/Kg 4/22/

128in Einzel focusing lens is turned on Red lines are equipotential lines Blue lines are trajectories of dust

37 Pre-acceleration with Focusing Dust Reservoir Extraction Plate Einzel Lens (off) Pelletron Entrance +16kV +20kV Ground 3.128in Einzel focusing lens is turned on Red lines are equipotential lines Blue lines are trajectories of dust particles Charge to Mass Ratio is ~17 C/Kg 75kV Dust is modeled as a point source fired in a 30 o cone from tip of needle in dust reservoir Particles are roughly parallel after entering Pelletron 4/22/

collimated Final spot is larger than size of beam line ~6 With

38 Final Beam Spot Walls of Beam line Dust particles hitting wall Einzel off Einzel on Without focusing lens, beam is not collimated Final spot is larger than size of beam line ~6 With lens on, beam is collimated Spot size: ~0.5mm diameter 1mm 4/22/

39 Current Beamline Detectors 3MV Pelletron Particle Selection Unit 4/22/

40 Future Work Attach beam line to LEIL target chamber Prepare for first user on May 1 st Lunar Retroreflector material studies Finish PSU testing and implement FPGA Prepare stand for UHV chamber and connection to beam line Start shooting dust at stuff! CCLDAS Website - lasp.colorado.edu/ccldas Lab Webcam - dustcam.colorado.edu 4/22/

41 Timelapse 4/22/

42 Detector Signals - Bad Bad Signals are hard to filter out Noise Unexplained upside signals Particles hitting detectors Slow particles do not appear as square waves 4/22/

43 Distributions 4/22/

44 Distributions 4/22/

Laboratory Studies of Lunar Dust Transport

Laboratory Studies of Lunar Dust Transport X. Wang, M. Horanyi and S. Robertson Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS) 4.15.2010 Lunar plasma Environment Evidence of electrostatic