introducing the tof-acsm - welcome |...
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62 * 58 * 48 cm
Introducing the ToF-ACSM
presented by Mike Cubison, Tofwerk AG
Aerodyne ACSM
● Aerosol Chemical Speciation Monitor
● The instrument presented here:● has NO CHOPPER● has hardware setup optimised for MONITORING
It is not the mini-AMS! (Pete is up next to talk about that)
But it shares many features with it
Design criteria - Hardware
Design criteria - Hardware● Use a TOF spectrometer … !
● Seek compromise between sensitivity and $$● m/dm sufficient for unit-mass analysis with clear baseline determination
“E-TOF”
Design criteria - Hardware● Use a TOF spectrometer … !
● Seek compromise between sensitivity and $$● m/dm sufficient for unit-mass analysis with clear baseline determination
● Minimise size & weight
Design criteria - Hardware● Use a TOF spectrometer … !
● Seek compromise between sensitivity and $$● m/dm sufficient for unit-mass analysis with clear baseline determination
● Minimise size & weight● Orientation not constrained
The “Taurus”
Design criteria - Hardware● Use a TOF spectrometer … !
● Seek compromise between sensitivity and $$● m/dm sufficient for unit-mass analysis with clear baseline determination
● Minimise size & weight● Orientation not constrained● Simple vacuum system
Only 2 pumps
Design criteria - Hardware● Use a TOF spectrometer … !
● Seek compromise between sensitivity and $$● m/dm sufficient for unit-mass analysis with clear baseline determination
● Minimise size & weight● Orientation not constrained● Simple vacuum system● Electronics capable of handling upgraded spectrometer
“TPS 2.0”
One TOF power supply for all Tofwerk spectrometers
Design criteria - Hardware● Use a TOF spectrometer … !
● Seek compromise between sensitivity and $$● m/dm sufficient for unit-mass analysis with clear baseline determination
● Minimise size & weight● Orientation not constrained● Simple vacuum system● Electronics capable of handling upgraded spectrometer● Robust detector
● can handle atmospheric pressure● long lifetime
SGE dynode detector
Operation voltage range: 2850 → 4500 V
after 2 months continuous operation we are running at 3000 V
Design criteria - Hardware● Use a TOF spectrometer … !
● Seek compromise between sensitivity and $$● m/dm sufficient for unit-mass analysis with clear baseline determination
● Minimise size & weight● Orientation not constrained● Simple vacuum system● Electronics capable of handling upgraded spectrometer● Robust detector
● can handle atmospheric pressure● long lifetime
● Data acquisition (DAQ) system● Large dynamic range● Economical● Data rate sufficient for m/dm of spectrometer... and not more● Averaging and thresholding → noise suppression
The new DAQ system
SP Devices ADQ114
● Large dynamic range → signal is digitised into 214 discrete levels● Economical → internal timing → no NI timer card● Appropriate data rate
● 0.8 Gsamples/s, up to 200 MS per second at ~100% duty cycle● Averaging and thresholding
● On-board averaging of 64 kExtractions (~ 1 second)
Design criteria - Software
Challenge: Design DAQ and analysis software that
1) Gives basic ACSM time-series data with minimal user input
2) Provides an environment for academic users to perform complex data analysis tasks
Design criteria - Software● Layered, modular DAQ software
● Acquisition through library → not hardware specific● User-interface and acquisition handled separately
REALLY easy-to-use DAQ interface
supported by
a complex full-featured recording exectuable
Design criteria - Software● Layered, modular DAQ software
● Acquisition through library → not hardware specific● User-interface and acquisition handled separately
● Automated data crunching● No need for post-processing to get at time series data
Design criteria - Software● Layered, modular DAQ software
● Acquisition through library → not hardware specific● User-interface and acquisition handled separately
● Automated data crunching● No need for post-processing to get at time series data
● Automated start-up and operation● Resume acquisition upon hard restart● Control instrument voltages● Handle interlock condition● Maintain detector sensitivity
Design criteria - Software● Layered, modular DAQ software
● Acquisition through library → not hardware specific● User-interface and acquisition handled separately
● Automated data crunching● No need for post-processing to get at time series data
● Automated start-up and operation● Resume acquisition upon hard restart● Control instrument voltages● Handle interlock condition● Maintain detector sensitivity
● Full remote-control capability● Not just remote desktop● Auto-export to web → data accessible via PC / phone app● Control basic instrument functions via web-based applications
All in all, what is new?
Shared with the AMS family Specific to ToF-ACSMSpectrometer * Spectrometer *
Detector * Detector *
Aerodynamic inlet DAQ hardware & software
Heater & ioniser Vacuum system (except backing pump)
TOF pulser & pre-amplifier Electronics (TPS, heater etc)
Distribution & support by Aerodyne PC
* The TOF and detector are “hot-swappable” with this instrument!
Prototype has:● Grid-less E-TOF → less performance, less $$● SGE dynode detector → less ions detected, longer lifetime, robustness
→ minimising price at expense of performance: the “monitoring” instrument
Measuring aerosol
Standard AMS aerodynamic lens(Liu 1995, Zhang 2002,2004)
ACSM inlet-valveswitching system(Ng 2011)
Orifice
a very important design criterium
Measuring aerosolcf ToF-AMS “Fast mode” (Kimmel et al, 2011)
Duty cycle: Bkgnd = 17 %Total = 73 %
3-sigma(ng/m3)
Q-ACSM (Jayne, pers
comm.)
ToF-ACSM (SGE, E-TOF)
Ammonium 2656 170*
Organic 1380 198Sulphate 230 17Nitrate 103 19
Chloride 97 9
1-minute sensitivity limits
But the big problem is the interference of air molecules in the organic fragmentation pattern
→ we have to work out how to pump them away
● Mass range of TOF up to 200 Th● Only to 100 Th → sensitivity up 25%
● Detector voltage set low to maximise lifetime
● Using dynode detector● MCPs → sensitivity up 100%
● Using E-TOF● C-TOF → sensitivity up 40 %
* Using new frags!
Ammonium fragmentation
ARCTAS H-ToF-AMS dataCalifornia Central Valley
Example of sensitivity
Organic “difference” time-series
Test sensitivity for real
Jungfraujoch High-Alpine Research Station
TofwerkThun, Switzerland
JFJ lab
In conclusion
There is another new member of the AMS family
● Small and convenient
● Improved specs on the DAQ and electronics
● In monitoring configuration, sensitivity is ~ 10 x that of the Quad
● Full remote control, including from mobile platforms
● Automatic data-crunching
● “Involved” complex post-processing still available for academics!
● Choice of spectrometer and detector to suit application
● There is more work to be done on the vacuum system!!
Cheers to
Go visit Aerodyne in the exhibitors hall
The ToF-ACSM was realised thanks to
Aerodyne:John JayneJoel KimmelDoug Worsnop
Drexel:Pete DeCarlo
PSI:Roman FröhlichAndre PrévôtJay SlowikUrs Baltensperger
Tofwerk:Urs RohnerChristian TannerMarc GoninKatrin Fuhrer
Funding:KTI
END