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