Ion Trap

[Pigeon]

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. The two most common types of ion traps are the Penning trap and the Paul trap (quadrupole ion trap).

When using ion traps for scientific studies of quantum state manipulation, the Paul trap is most often used. This work may lead to a trapped ion quantum computer and has already been used to create the world's most accurate atomic clocks.

In an electron gun (a device emitting high-speed electrons, such as those in CRTs), an ion trap may be implemented above the cathode (using an extra, positively-charged electrode between the cathode and the extraction electrode) to prevent its degradation by positive ions accelerated backward by the fields intended to pull electrons away from the cathode.

Ion trap used with a quantum computer.

Paul ion trap

A Paul trap is a type of quadrupole ion trap that uses static direct current (DC) and radio frequency (RF) oscillating electric fields to trap ions.

Paul traps are commonly used as a components of a mass spectrometer.

The invention of the 3D quadrupole ion trap itself is attributed to Wolfgang Paul who shared the Nobel Prize in Physics in 1989 for this work. The trap consists of two hyperbolic metal electrodes with their foci facing each other and a hyperbolic ring electrode halfway between the other two electrodes. Ions are trapped in the space between these three electrodes by the oscillating and static electric fields.

[Pigeon]

Calutron

A calutron is a mass spectrometer used for separating the isotopes of uranium. It was developed by Ernest O. Lawrence during the Manhattan Project and was similar to the cyclotron invented by Lawrence.

Its name is a concatenation of Cal. U.-tron, in tribute to the University of California, Lawrence's institution and the contractor of the Los Alamos laboratory. They implemented industrial scale uranium enrichment at the Oak Ridge Y-12 plant established during the war and provided much of the uranium used for the "Little Boy" nuclear weapon, which was dropped on Hiroshima in 1945.

In a mass spectrometer, a vaporized sample is bombarded with high-energy electrons, which cause the sample components to become positively charged ions. They are then accelerated by electric fields and subsequently deflected by magnetic fields, ultimately colliding with a plate and producing a measurable electric current.

Since the ions of the different isotopes have the same electric charge but different masses, the heavier isotopes are bent less by the magnetic field, causing the beam of particles to separate out into several beams by mass, striking the plate at different locations. The mass of the ions can be calculated according to the strength of the field and the charge of the ions.

An ordinary mass spectrometer is designed to analyse the composition of very small samples; the calutron uses the same principle, but is designed to separate substantial quantities of known isotopes.

Initially a type of calutron known as Alpha was used; it enriched uranium to about 15% 235U. A later design, called Beta, further enriched the output of Alpha, optimising the initial design for the smaller quantities of already enriched feedstock.

Due to the wartime copper shortage, the electromagnets were made using thousands of tons of silver borrowed from the U.S. Treasury. To take full advantage of the required large electromagnet, multiple calutrons were arranged around it in a large oval, called a race track because of its shape.

Magnetic separation was later abandoned in favor of the more complicated, but more effective, gaseous diffusion method.