New Mass Spectrometers for NBC

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New Mass Spectrometers for NBC Environmental
CharacterizationMid-Year ReviewF.S. Anderson
E. Pilger, University of Hawaii
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Basics

• New Mass Spectrometers for NBC Environmental
  Characterization
• University of Hawaii/HIGP
• Lead F. Scott Anderson (50)
• Personnel
• Eric Pilger Physicist (50)
• Lloyd French - ME (25)
• Gary McMurtry - Spectroscopist (10)
• Karen Stockstill (Postdoc 50)
• David Hampton - ME (20)
• Jim Jolly - EE (10)

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Program Details

• Date of award 8/10/2004
• Date of receipt of funds 9/1/2004
• Date work actually started 9/1/2004
• Percent of work completed to date 85
• Proposed 2 year program
• Transitioning to entirely to partnership program
  after 1.5 years

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Objectives

• Explore fundamental new technological MS
  approaches to MASINT signatures
• ESI RFMS (leverages NASA MIDP)
• RFMS New mass filtering method
• Explore with EI (gas) ESI (liquids)
• ESI Applied under simpler in-situ relevant
  conditions, I.e. vacuum
• LA-RI-MS (leverages NASA PIDDP, NAI, ONR IED)
• New application of RI-MS to in-situ
  ultra-sensitive detection
• New MBTOF MS
• 2 Talks
• NSF EI-RFMS
• Partnership LA-RI-MS

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RFMS Results Summary
Started with RFMS design from JPL with variety of
problems
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RFMS

• Last Review
• Demonstrated signals consistent with ion
  detection
• Not interpretable at that time
• Well developed theory
• Unique spectrograph property
• Allows simultaneous measurement of multiple
  masses
• Useful with imaging detectors
• Shock tolerance
• Simple e-fields
• No upper limit to mass range

• Identified errors
• Needs good vacuum
• Initial theory of operation significantly
  incorrect!

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EI-RFMS Operation
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Theory of Mass Dispersion
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Theory of Mass Dispersion
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Ideal Instantaneous RF Filter
Model

• Theoretical air spectrum
• All masses enter simultaneously
• Frequencies sweep to push masses from center
• Light first
• Heavy last
• Characteristics
• Inside radius r ion paths cross
• Outside uniform flight to fixed radius
• Each peak crossing detector causes spectral peak

Ion Beam
Detector
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Poor Instantaneous RF Filter
Model

• Theoretical air spectrum
• All masses enter simultaneously
• Frequencies sweep to push masses from center
• Characteristics
• Beam larger than detector
• All displacement onto detector
• Non-unique movement on detector
• Non-unique result
• Beam width/detector size critical

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Old Instantaneous RF Filter
Model

• Model of data from our previous talk
• Theoretical air spectrum
• Illustrates need for good beam quality
• Can only readily see 2 peaks (H2O, N2)
• Spectrum not-conclusive

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Ideal Continuous RF Filter
Model

• Ions not pulsed, not points on detector
• As RF rotates, rings are formed
• Theoretical air spectrum
• All masses enter continuously
• Frequencies sweep to push masses from center
• Light first
• Heavy last
• Unfortunately, still getting muddy spectra
• Sought to image beam/rings

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Measuring Beam Width
Detector Plates

• Beam/Detector width critical
• Causes of beam spreading
• Poor vacuum
• Stray E-fields
• Poor RF generation
• Increased vacuum
• Markedly better results
• Changed detector
• Added tube
• Bought better OTS RF generator
• We continue to work to minimize beam width

RF Electrodes
Ion Beam
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Measuring Beam Width
Backplate Signal

• Seek to visualize beam
• Raster beam across small hole in detector using
  DC on RF plates (like TV)
• Changed detector
• Added small hole
• Success - could image beam
• Depending on vacuum, beam width from 0.7 to 1 mm

Detector Plates
RF Electrodes
Ion Beam
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Imaging RF Filter
Backplate Signal

• Always desired ring visualization
• Could not see bullseye patterns
• Realized could combine DC raster and RF on same
  electrodes
• Create ring pattern and raster it across central
  aperture

Detector Plates
RF Electrodes
Ion Beam
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RF Filter True Beam Width
Model
Continuous Source Rastered
Pulsed Source Rastered
Beam width like true beam width (0.7-1 mm)
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First Real Data FC-43

• Began testing steering to image expected bullseye
  patterns
• Commonly got uninterpretible data
• Fixes to RF subsystem resulted in this
  low-resolution image
• FC43 is a common MS calibration compound for mass
  50-600

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Medium Res FC-43 Data

• Repeated the experiment with a higher resolution
  steering scan
• Asymmetry indicates RF electrode shape
  non-optimal
• Sharper fin electrodes in next revision
• Can use these images to derive masses present
• Can also use electrodes, though some loss of
  resolution due to non-circularity

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Higher Res FC-43 Data

• Scan of lower right quadrant at higher resolution
• Three dominant masses in FC43 are visible
• Realized could measure spectra at one point on
  rings or reduce rings to calculated spectrum

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FC-43 Data
Resolution 5
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Air Data
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Celebration Crown Royal Data
Note that Crown Royal is consistent with watery
Ethyl Alcohol
Remnant FC43
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What next?

• Why is resolution low?
• Beam/Detector large with respect to dispersion
• Vacuum poor
• Theoretical resolution of 8000 / mm
• Current beam 1000 mm
• Better resolution
• Continued work to focus beam
• EI tuning
• Better e- curtain
• Better einzel lens
• Smaller apertures

• Better resolution (cont)
• Better vacuum
• Higher sensitivity detector
• Allows additional reductions in aperture size
• Higher resolution detector
• Detects smaller rings
• Larger RF amplitudes
• Enables larger dispersion
• Can use steering to measure parts of beam at
  distances gt actual detector size
• R100 should be possible

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Ion Focus Better Einzel Designs

• Initial design Einzel
• Increased signal focus
• Poor DOF
• Current -Einzel
• Better DOF
• Better focus for all masses
• Better focal range
• Future
• Try tube lens arrangement
• Others

Positive Einzel
Negative Einzel
Tube lens
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Implications

• New RFMS technique demonstrated
• No mass limit
• Spectrograph property
• Can measure multiple masses simultaneously
• Mechanical requirements low
• Issues
• Moderate resolution technique for in-situ sizes
• Standard vacuum requirements
• Applications
• Remote in-situ ESI of liquids unlikely to have
  sufficient resolution or vacuum
• ESI could be used with our MB-TOF development,
  however
• Remote, rugged, in-situ EI remains possible

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RFMS Results Summary
RFMS
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Completed Lab for LA-RI-MS
All deliveries within next 2 weeks!
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Layout with Storage Source
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MB-TOF Resolution Progress

• RM/dMt/dt
• Critical minimize dt
• Orthogonal source
• Could be hand tuned to 8-10 ns for one mass
• New storage source
• Increases resolution over whole mass range
• Typically 20 ns without tuning
• Better preamplifier resulted in reduction to 8 ns
• Further tuning will be better yet
• Reduce ringing

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NdYVO4 Optical Power Amplifier

• First prototype
• Water cooler
• Based on available parts
• Limited shot system could utilize air cooling

Cold plate/Water Re-circulator System utilized to
remove thermal load generated by Laser Diode Bars.

• Optical Power Amplifier Performance
• Energy 185uJ/Pulse
• Repetition Rate 1.1kHz
• Pulse Width 720ps
• Optical Power 204mW
• Optical Gain 18.5X
• Polarization Contrast Ratio 60 to 1

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ZZ-TOF

• Outgrowth of MB-TOF
• Easier to measure all masses simultaneously
• Lower power
• No pulsing
• Smaller

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LARIMS Results Summary
Extensive leveraging of late NASA PIDDP funds
(arrived 11/05) Ongoing leverage from NASA NAI,
ONR IED Program Work transitioned from NSF to
Partnership Program
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Honest Assessment

• EI/ESI-RFMS
• Fundamental new MS technique demonstrated
• Potential for use of modified EI source to make
  highly focused beam in other applications
• Demonstration of ESI
• Use in variety of vacuum conditions possible
• More work in defining source characteristics
• Range of possible applications reduced to
  probable
• Low vacuum use unlikely
• ESI in ballistic shock-tolerant mode unlikely
• Methods for applying these ideas will evolve
• Ready for more focused work in Partnership
  Program
• LA-RI-MS Despite slow funding start
• LA RI design complete
• Lab Lasers in place
• TOF and High Speed DAQ arriving this week
• ONR IED initial miniature high powered laser
  construction underway
• MB-TOF continues to evolve