Ion trap

An ion trap is a combination of electric or magnetic fields used to capture charged particles, often in a system isolated from an external environment. Ion traps have a number of scientific uses such as mass spectrometry, basic physics research, and controlling quantum states. The two most common types of ion trap are the Penning trap, which forms a potential via a combination of electric and magnetic fields, and the Paul trap which forms a potential via a combination of static and oscillating electric fields.

Penning traps can be used for precise magnetic measurements in spectroscopy. Studies of quantum state manipulation most often use the Paul trap. This may lead to a trapped ion quantum computer and has already been used to create the world's most accurate atomic clocks.Electron guns (a device emitting high-speed electrons, used in CRTs) can use an ion trap to prevent degradation of the cathode by positive ions.

An ion trap mass spectrometer may incorporate a Penning trap (Fourier transform ion cyclotron resonance),Paul trap or the Kingdon trap. The Orbitrap, introduced in 2005, is based on the Kingdon trap. Other types of mass spectrometers may also use a linear quadrupole ion trap as a selective mass filter.

A Penning trap stores charged particles using a strong homogeneous axial magnetic field to confine particles radially and a quadrupole electric field to confine the particles axially. The Penning Trap was named after Frans Michel Penning by Hans Georg Dehmelt who built the first trap. Penning traps are well suited for measurements of the properties of ions and stable charged subatomic particles. Precision studies of the electron magnetic moment by Dehmelt and others are an important topic in modern physics.

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