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