Kingdon trap
Encyclopedia
A Kingdon trap is a type of ion trap
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In the Kingdon trap there is no potential minimum to store the ions; however, they are stored with a finite angular momentum about the central wire and the applied electric field in the device allows for the stability of the ion trajectories. It consists of a thin central wire, an outer cylindrical electrode and isolated end cap electrodes at both ends. A static applied voltage results in a radial logarithmic potential between the electrodes. In 1981, Knight introduced a modified outer electrode that included an axial quadrupole term that confines the ions on the trap axis. The dynamic Kingdon Trap has an additional AC voltage that uses strong defocusing to permanently store charged particles. The dynamic Kingdon Trap does not require the trapped ions to have angular momentum with respect to the filament. An Orbitrap
is a modified Kingdon trap has been used for mass spectrometry
. Though the idea has been suggested and computer simulations performed neither the Kingdon nor the Knight configurations were reported to produce mass spectra, as the simulations indicated mass resolving power would be problematic.
Ion trap
An ion trap is a combination of electric or magnetic fields that captures ions in a region of a vacuum system or tube. Ion traps have a number of scientific uses such as mass spectrometery and trapping ions while the ion's quantum state is manipulated...
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In the Kingdon trap there is no potential minimum to store the ions; however, they are stored with a finite angular momentum about the central wire and the applied electric field in the device allows for the stability of the ion trajectories. It consists of a thin central wire, an outer cylindrical electrode and isolated end cap electrodes at both ends. A static applied voltage results in a radial logarithmic potential between the electrodes. In 1981, Knight introduced a modified outer electrode that included an axial quadrupole term that confines the ions on the trap axis. The dynamic Kingdon Trap has an additional AC voltage that uses strong defocusing to permanently store charged particles. The dynamic Kingdon Trap does not require the trapped ions to have angular momentum with respect to the filament. An Orbitrap
Orbitrap
An orbitrap is a type of mass spectrometer invented by Alexander Makarov. It consists of an outer barrel-like electrode and a coaxial inner spindle-like electrode that form an electrostatic field with quadro-logarithmic potential distribution....
is a modified Kingdon trap has been used for mass spectrometry
Mass spectrometry
Mass spectrometry is an analytical technique that measures the mass-to-charge ratio of charged particles.It is used for determining masses of particles, for determining the elemental composition of a sample or molecule, and for elucidating the chemical structures of molecules, such as peptides and...
. Though the idea has been suggested and computer simulations performed neither the Kingdon nor the Knight configurations were reported to produce mass spectra, as the simulations indicated mass resolving power would be problematic.