cpots2012.physics.uoc.gr Dept. of Physics, University of Crete Aug 19 – Sept 2, 2012
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Transcript of cpots2012.physics.uoc.gr Dept. of Physics, University of Crete Aug 19 – Sept 2, 2012
CPOTS – 2nd ERASMUS Intensive ProgramIntroduction to Charged Particle Optics: Theory and
Simulation
http://cpots2012.physics.uoc.grDept. of Physics, University of Crete
Aug 19 – Sept 2, 2012 Heraklion, Crete, GREECE
http://cpots2012.physics.uoc.gr 2
Group Project
Magnetic Bottle Electron Spectrometer
Nimet OkumuşSocrates Anastasopoulos
David Alcocer Velarde
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Abstract
The principles of magnetic bottle mass spectrometer
Theoretical analysis
Energy resolution of magnetic bottle spectrometer
Conclusions
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Magnetic Bottle Electron Spectrometer
• Electrons spiral in B field which reduces adiabatically
• Electron energy measured by time of flight to detector
• Lets use a standard spectrometer, e.g. hemispherical analyser with an
entrance aperture
• Very small solid angle, most electrons lost!
• 4 collection of electrons
Weak uniform B field Strong
B field
The use of permanent magnets requires modifications of the transition region (between the high-field electron production zone and the low-field drift tube analyzer) to avoid axial field reversals associated with fringing fields.
e-
e-
e-
e-
Analyser
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Investigate Spectrometer Properties
• Measure the time of flight for electrons with different conditions (using Record function)
• Find the energy resolution of the spectrometer in different situation
SIMION Magnetic Bottle SpectrometerParticles Definition
SIMION Magnetic Bottle Spectrometer
Flying Particles Three different group with energy 40, 20, 5 eV
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SIMION Modelling of Magnetic Bottle Spectrometer
Energy Resolution of Spectrometer
K is constant.
From this 2 equations we exported the relation between
Kinetic Energy and TOF
SIM
ION
Mag
netic
Bott
le
Spec
trom
eter
Bi=2000 gaussBf=10 gaussTransition Region=9 mm
K=0.179574 eV µsec²Calibration factor=KE×(TOF)2
Convertion TOF to KE
TOF KE
Magnetic Bottle Spectrometer Resolution
The resolution of the Spectrometer is: 10%
CPOTS 2012: S9 - JBG http://cpots2012.physics.uoc.gr 12/XX
ΔKE
Energy resolution = 19.75 eV/(20.6-18.6) eV ≈10%
ΔKE
Energy resolution = 9.95 eV/(10.4-9.4) eV ≈ 10%
Energy resolution doesn’t depend on KE.
CPOTS 2012: S9 - JBG http://cpots2012.physics.uoc.gr 13/XX
Resolution= 9.6 / (10.35-8.9)=6.6%
Bi= 3000 Gauss
ΔKE
Bi=8000 Gauss
ΔKE
Resolution= 8.6/ (10.25-7.1)=2.7%
Resolution
CPOTS 2012: S9 - JBG http://cpots2012.physics.uoc.gr 14/XX
Conclusion
Resolution of spectrometer is depent on length of the time of flight tube.
The resolution changes with B field .
Energy resolution doesn’t depend on KE.
Thank you for your attention