1
AMSHardware / Upgrades / Development
Performance Operational
AMS Users MeetingOct. 13, 2002
Problems, failures and
some general comments
Hardware Upgrades Planned for 2001
☯ Adjustable lens system
☯ 16 mm Quad system
☯ Differentially pumped ionizer/quad region
☯ Alcatel hybrid pump
☯ Channel apertures
☯ Porous conical heater with thermocouple
☯ Redesigned electronics boxes/reduced cabling
☯ Inlet pressure gauge for sample flow rate.
2
Chamber DeliveryOwner Serial No. Date Comment
1 Caltech 205-01 Sep-00 Upgraded, June-022 ARI - I 255-01 Jun-003 UMIST 255-02 Sep-00 Upgraded, May-024 U. Colorado-Toohey 255-03 Jun-015 SUNY 255-04 Mar-01 Upgraded, April-026 Arizona 255-05 Mar-01 7 CEH-Scotland 255-06 Jun-018 MPI -Mainz 255-07 Jun-01 Upgraded, April-029 ARI - II 255-08 Jan-0210 U. Tokyo 255-09 Mar-02 First w/V301 on front11 UMIST Flight 255-10 Jun-0212 NOAA 255-11 May-0213 Env. Canada 255-12 May-0215 DOE 255-13 Jun-02 First with sm. Ionizer14 U. Colorado-Jimenez 255-1415 Julich 255-1516 NIES/Sanyu17 JCAP/Sanyu18 Utah State
8mm Quad systems
Summary of AMS Systems
New chamber design
V301 on inlet.
Supports high thru-put lens
No differential Pumping of ionizer
Component Status Result/Impact High emission current ionizer (increased V6/V7 resolution)
Tested Balzers IS420 special
Signals increase linearly (~4x) up to 8 mA. Detrimental to tungsten filament lifetime. Need to evaluate filament coatings to reduce work function.
Reduced volume ionizer
Tested evaluation unit from Balzers
~2x increase in NO3 IE. Selectively improves particle plume ionization.
Closed source ionizer
Tested ~50% increase in IE.
Ionizer magnets Tested ~2x increase in IE but also increase single particle pulse width…size resolution.
Performance UpgradesIonizer
3
Standard Cross Beam Ionizer ModificationStandard Ionizer
Before modification After modification
50% increase in signal. Close-up ionizer more...
1/4” x 1/4” x .005” 316 stainless steel shim stock.
Lightly spot weld this piece (~6 W*Sec) to top of ionizer to cover hole.
500
400
300
200
100
0
Sing
le P
artic
le S
igna
l (N
O2+ io
n)
400x10-6350300250200150100500-50-100-150-200Time (s)
No magnets, std. ionizer Magnets on sm. vol. ionizer
Effect of Magnets on Single Particle Pulse Width
Approximately doubles pulse width. Long tail affects size resolution measurement.
1800 IPP 350 nm NO3IE ~8x10-6
4
10-3
10-2
10-1
100
101
102
103
104
200150100500
Mass
MSClosed_R85 6 mA MSClosed_R81 4 mA MSClosed_R75 2.5 mA
Double and triple charged W ions dominate
High Emission Current OperationMass spectra at normal (2.5 mA) medium and high emission
current settings
Signals as a function of emission current increase linearly up to 5mA then appear to saturate, except tungsten [log scale] (small contribution of surface ionization?).
Ionizer was retuned at each new emission current setting.
1200
1000
800
600
400
200
0
IPP
(30+
46)
654321
Emission Current (mA)
10x106
8
6
4
2
0
Air Beam (H
z)
102
103
104
105
106
107
Tung
sten
Sig
nal (
Hz)
6x10-6
5
4
3
2
1
Ionization Eff. (Ions/Molec.)
AB_Hz (28) W_Sig (m183) IE (350nm NH4NO3) IPP_30_46 (350nm NH4NO3)
High Emission Current Operation Summary
5
16
14
12
10
8
6
4
ln(W
sig
nal)
2.01.81.61.41.21.00.80.6
ln(Emission Current, mA)
fit_LnW_Sig= W_coef[0]+W_coef[1]*x W_coef={0.62732,7.6277} a = 0.62732 ± 0.478 b = 7.6277 ± 0.36
Tungsten ion signal increases as the 7.6 power of emission current
Filament lifetime: If the lifetime of the filament is directly proportional to its vapor pressure (ion signal) and that the average life time of the filament at 2.5 mA is 1.5 years then at 5 mA it may last 1.5 days and at 6 mA only 8 hours!
-8
-6
-4
-2
ln(W
sig
/ N
2 D
iff S
ig)
m/z
181
1.51.00.50.0
Ln(mA)
2% Thoriated Tungsten Pure Tungsten
This result compares standard tungsten to 2% thoriated tungsten filament.
No apparent reduction in tungsten signal for the thoriated filament set (??)Alloy vs surface coating?
Evaluate filament coatingsWant more emission at lower temperature/power
Reduce W work function.
6
Closed ionizer(50% increase in signal)
Summary of Ionizer Enhancements
IE 2x10-6
IPP = 400
IE 4x10-6
IPP = 800
Small Volume Ionizer(2x increase in S/N)
IE 8x10-6
IPP = 2000
Magnets(~2x increase, impact on size res.)
IE 3x10-5
IPP = 8000+?
High emission current ionizer(~4x increase, dynamic range limited...)
Need to evaluate S/N increase
Component Status Result/Impact High throughput lens
Designed. Needs to be built.
2-3 times more sample flow…SIGNAL. Requires V301 on front.
Converging inlet Tested qualitatively, find someone who can fabricate it.
Increase transmission of micron size particles. (PM1 vs PM2.5 measurement)
Conversion dynode mltiplier
Tested Balzers SEV218. Mass bias eliminated but ion collection reduced.
Eliminate mass bias. Enhance ion collection efficiency.
Restek (glass) coating on detection cylinder.
Implemented. Not yet quantified.
To reduce water and organic adsorption.
Performance Upgradesother
7
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
SI, r
elat
ive
to m
z 11
400350300250200150100500
Ion Mass
ETP AF133 SEM 218 with CD (Balzers)
usres/jayne/igor/SGE_MultGain.pxp
Conversion Dynode Result
Not shown, but ion collection efficiency with SEV218 ~ 2x less than SEV217
Summary of Performance Upgrades
Combining ionizer improvements
+ high throughput lens…
…expect mass concentrations detection limitsapproaching several ng m-3 in several minutes
Achieving ionization efficiencies in the 10-5 range.Probably reached the limit?
8
Component Result/Impact Status Temperature controlled inlet.
Get to the bottom of the scaling factor.
Tested, being revised.
Inlet temperature, pressure and RH measurement.
More information on sample conditions.
Needs to be implemented.
New rack system. Transport fully assembled, simplifies setup.
On the drawing table.
Beam width probe. Get to the bottom of the scaling factor
Needs to be engineered.
Optical Particle Detection.
Detection on non volatile particles. Higher size resolution measurement.
Prototype being tested. Under development.
Operational Upgrades/Development
QMG422
EC
TPC
Computer
PS
UPS
Monitorkey board
24”
46”
35”
41”
9
Design allows instrument to be mounted left of right handed
Top portion of rack can be easily removed to service AMS
1.0
0.8
0.6
0.4
0.2
Tran
smis
sion
-0.4 -0.2 0.0 0.2 0.4
Wire Position (mm)
75 µ
m d
iam
eter
wire
350 nm NH4NO3 DOP
wires.pxp
Moveable Wire Measures Beam Width
Is scaling factor related to beam width and decreased particle collection?
10
Sample flow from isokinetic
inlet(0.1 LPM)
Temperature Regulated Inlet
To AMSCouples to 1/8”
Cajon fitting housing critical
aperture
Heating/cooling fluid flow
Optional temperature port
1/8” Swagelok Union with Teflon and graphite ferrules. Position TC junction in gas stream without contact to walls
Type K thermocouple with exposed
junction
New design using Peltier cooler being tested at BC
Light Scattering Modulesub-assemblies
Diode pumped green laser532 nm 25 mW
Main development challenge is reducing scatter light
Test version deployed during ITCT
11
Beam width probe(solve the scaling factor)
Converging aperture(a true PM2.5 instrument)
Most Important Developmentsare going to be...
Hardware Failures
Premature bearing failure of turbo pumps on front endInlet and back pressure too high
Alcatel Hybrid bearing problems new release planned for Oct. 2002
National Instruments fast board DAC failure.
Balzers Components RF QMH 410-5, IS420, recessed pins in ionizer connector
12
V301 premature bearing failure infant mortality case.
Vacuum Interlock (TP6), shut down of multiplier/heater/heater bias.
V70 controller reverts to low speed operation.
Pin-Hole assembly - tighteningover-tightening, deformation of disc low pressure side O-ring disrupts particle transmission
5V regulator failure on TPC related to Alcatel modification
Hardware Failures, cont’d
Difficulties...
Cabling which cable goes where, some left unconnected.
AMS Acquisition Program corrupt AMSmenu.prm
Balzers IS420 Loss of V6 and V7. Power glitch that resets SEM to FC and disables V6 and V7.
Computer Instabilities Dual vs Single CPU.
User Manual...troubleshooting and debugging section
13
5
4
3
2
1
0
Ion
Sign
al (m
z 46
)
4.8x10-34.64.44.24.0
TOF (s)
Chopper freq (Hz) 107.5 49.1 77.3 125.6 149.6 173.3 200.8
4.60x10-3
4.55
4.50
4.45
4.40
4.35
4.30
Peak
TO
F (s
)
25x10-320151050
1/Chopper Frequency
Chopper “Zero” IssueParticle TOF Spectra for
350 nm NH4NO3 DMA particles
If not zeroed exactly…
Particle velocity calibration will only be accurate for the chopper frequency it was calibrated.
Maintenance
Pin-hole assembly, check O-rings replace with 2-006
After a field mission clean the chamber and filters on all electronic components.
Routine check for leaks.
14
We’ve come a long way
AMS system that demonstrated proof of concept1997
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
SI, r
elat
ive
to m
z 11
400350300250200150100500
Ion Mass
ETP AF133 SEM 218 with CD (Balzers)
usres/jayne/igor/SGE_MultGain.pxp
140
120
100
80
60
40
20
0
Sign
al
5040302010
AMU
FC biased with V7 (11V) FC at GND
15
15x10-3
10
5
0
m/z 48 at 2.5 m
A
0.0080.0060.0040.0020.000
TOF (s)
50x10-3
40
30
20
10
0
m/z
48 a
t 5 m
ACompare S/N for two different emmision currentsAmbient sulfate signal 200 sec average time
Sig_p48_R86 5.0 mA Sig_p48_R87 2.5 mA
Is there an advantage of operating at high emission current?
This result suggests that operating at 5 mA does not have a significant advantage since the S/N is the same as operating at lower current (2.5 mA). (A big disadvantage of high emission current operation is the large tungsten
signal and reduced filament lifetime)
