CPOTS – 2nd ERASMUS Intensive Program Introduction to Charged Particle Optics: Theory and Simulation http://cpots2012.physics.uoc.gr Dept. of Physics, University of Crete Aug 19 – Sept 2, 2012 Heraklion, Crete, GREECE Group Project Magnetic Bottle Electron Spectrometer Nimet Okumuş Socrates Anastasopoulos David Alcocer Velarde http://cpots2012.physics.uoc.gr 2 Abstract The principles of magnetic bottle mass spectrometer Theoretical analysis Energy resolution of magnetic bottle spectrometer Conclusions 3 Magnetic Bottle Electron Spectrometer Weak uniform 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. Strong B field • 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 e- entrance aperture • Very small solid angle, most electrons lost! • 4 collection of electrons Analyser eee- 4 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 5 SIMION Magnetic Bottle Spectrometer Particles Definition SIMION Magnetic Bottle Spectrometer Flying Particles Three different group with energy 40, 20, 5 eV SIMION Modelling of Magnetic Bottle Spectrometer From this 2 equations we exported the relation between Kinetic Energy and TOF K is constant. Energy Resolution of Spectrometer 8 SIMION Magnetic Bottle Spectrometer Bi=2000 gauss Bf=10 gauss Transition Region=9 mm Calibration factor=KE×(TOF)2 K=0.179574 eV µsec² Convertion TOF to KE TOF KE Magnetic Bottle Spectrometer Resolution The resolution of the Spectrometer is: 10% Energy resolution = 19.75 eV/(20.6-18.6) eV ≈10% Energy resolution = 9.95 eV/(10.4-9.4) eV ≈ 10% Energy resolution doesn’t depend on KE. ΔKE CPOTS 2012: S9 - JBG ΔKE http://cpots2012.physics.uoc.gr 12/XX Resolution Resolution= 9.6 / (10.35-8.9)=6.6% Resolution= 8.6/ (10.25-7.1)=2.7% Bi= 3000 Gauss Bi=8000 Gauss ΔKE ΔKE CPOTS 2012: S9 - JBG http://cpots2012.physics.uoc.gr 13/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. CPOTS 2012: S9 - JBG http://cpots2012.physics.uoc.gr 14/XX