Kingdon Trap

Hande AkbasKealan Naughton

Alexander Fuchs-Fuchs

Kingdon Trap

Kingdon Trap with SIMION

•Create a working Kingdon trap in SIMION

•Results - Energy range of potentially trapped particles

•Improvements

What is a Kingdon Trap?•One of the first ion traps

•Radial trapping - two concentric cylinders with potential difference

•Axial trapping -ends with higher potential

•Ions are trapped in stable orbits if they possess the right angular momentum

•Static applied voltage results in a radial logarithmic potential between the electrodes

•Ions pulled in elliptical orbits

How it works

•Static applied voltage results in a radial logarithmic potential between the electrodes

•Ions pulled in elliptical orbits

The Kingdon Trap

•Symmetrical device

•Inner cylinder a wire

•Outer cylinder a hollow tube

•Put caps on the ends

Theory

•Maximum and minimum energies defined by maximum and minimum orbits

•Energy Max: 768 eV

•Energy Minimum: 43 eV

The Trap

•Outer cylinder radius: 50 mm

•Length: 300 mm

•Inner cylinder: 5mm

•The end caps separated by a few mm

SIMION steps

•Build the Geometry

•Fly the first particles

Getting the particles inside

•Problem: Sealed cylinder

•Make injection point

•This addition must be kept same potential as caps and outer cylinder, for uniform distribution

In action

Getting the particles inside

Defining the energy range

•Energy

•Too High: Collide with outer cylinder

•Too Low: Collide with inner rod

What we found

•Inner rod Potential: -3200 V

•Caps and cylinder: 20 V

•Minimum energy: 43 eV (38 eV)

•Max energy: 580 eV (768 eV)

•Mass independent

Improvements

•Never been reported to produce mass spectra

•Modified version - Orbitrap - used as a mass spectrometer

Orbitrap•Type of mass spectrometer

•outerbarrel-like electrode and coaxial inner spindle like electrode

•Electric field: quadro-logarithmic potential distribution

Orbitrap•Oscillation frequency: independent

of ion velocity, Inversely proportional to square root. Characteristic of the mass of the particle

•High accuracy: 1-2 ppm

•High resolving power: 200,000

•resolving power proportional to the number of harmonic oscillations

Conclusions

•Simulation of a working ion trap

•Defined energy range agrees with theory

•Upgrades can be made into a working mass spectrometer

Don’t get Caught