Electron beam ion trap (EBIT) is an

electromagnetic In physics, electromagnetism is an interaction that occurs between particles with electric charge. It is the second-strongest of the four fundamental interactions, after the strong force, and it is the dominant force in the interactions o ...

bottle that produces and confines

highly charged ion Highly charged ions (HCI) are ions in very high charge states due to the loss of many or most of their bound electrons by energetic collisions or high-energy photon absorption. Examples are 13-fold ionized iron, or Fe XIV in spectroscopic notatio ...

s. An EBIT uses an electron beam focused with a powerful magnetic field to

ionize Ionization, or Ionisation is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecule ...

atoms to high charge states by successive

electron The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no ...

impact. It was invented by M. Levine and R. Marrs at

LLNL Lawrence Livermore National Laboratory (LLNL) is a federal research facility in Livermore, California, United States. The lab was originally established as the University of California Radiation Laboratory, Livermore Branch in 1952 in response ...

and

LBNL Lawrence Berkeley National Laboratory (LBNL), commonly referred to as the Berkeley Lab, is a United States national laboratory that is owned by, and conducts scientific research on behalf of, the United States Department of Energy. Located in ...

Operation

The positive ions produced in the region where the atoms intercept the electron beam are tightly confined in their motion by the strong attraction exerted by the negative charge of the electron beam. Therefore, they orbit around the electron beam, crossing it frequently and giving rise to further collisions and ionization. To restrict the ion motion along the direction of the electron beam axis, trapping electrodes carrying positive voltages with respect to a central electrode are used. The resulting

ion trap An ion trap is a combination of electric and/or magnetic fields used to capture charged particles — known as ions — often in a system isolated from an external environment. Atomic and molecular ion traps have a number of applications in phy ...

can hold ions for many seconds and minutes, and conditions for reaching the highest charge states, up to bare uranium (U⁹²⁺) can be achieved in this way. The strong charge needed for radial confinement of the ions requires large electron beam currents of tens up to hundreds of

milliampere The ampere (, ; symbol: A), often shortened to amp,SI supports only the use of symbols and deprecates the use of abbreviations for units. is the unit of electric current in the International System of Units (SI). One ampere is equal to elect ...

. At the same time, high voltages (up to 200

kilovolts The volt (symbol: V) is the unit of electric potential, electric potential difference (voltage), and electromotive force in the International System of Units (SI). It is named after the Italian physicist Alessandro Volta (1745–1827). Defi ...

) are used for accelerating the electrons in order to achieve high charge states of the ions. To avoid charge reduction of ions by collisions with neutral atoms from which they can capture electrons, the vacuum in the apparatus is usually maintained at UHV levels, with typical pressure values of only 10⁻¹² torr, (~10⁻¹⁰ pascal).

Applications

EBITs are used to investigate the fundamental properties of

s e. g. by photon spectroscopy in particular in the context of relativistic

atomic structure Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons. Every solid, liquid, gas, and ...

theory and

quantum electrodynamics In particle physics, quantum electrodynamics (QED) is the relativistic quantum field theory of electrodynamics. In essence, it describes how light and matter interact and is the first theory where full agreement between quantum mechanics and spec ...

(QED). Their suitability to prepare and reproduce in a microscopic volume the conditions of high temperature

astrophysical plasma Astrophysical plasma is plasma outside of the Solar System. It is studied as part of astrophysics and is commonly observed in space. The accepted view of scientists is that much of the baryonic matter in the universe exists in this state. When ...

s and

magnetic confinement fusion Magnetic confinement fusion is an approach to generate thermonuclear fusion power that uses magnetic fields to confine fusion fuel in the form of a plasma. Magnetic confinement is one of two major branches of fusion energy research, along with ...

plasmas make them very appropriate research tools. Other fields include the study of their interactions with surfaces and possible applications to

microlithography Microlithography is a general name for any manufacturing process that can create a minutely patterned thin film of protective materials over a substrate, such as a silicon wafer, in order to protect selected areas of it during subsequent etchin ...

References

* * – First EBIT atomic spectroscopy measurement * * * * *

External links

* * *{{cite web , url=https://www.nist.gov/pml/div684/grp01/other-ebits.cfm , title=Other EBITs Around the Globe , date=14 December 2011 , publisher=National Institute of Standards and Technology , access-date=26 November 2012 Atomic physics Astrophysics Plasma physics Electromagnetism Electron beam American inventions Particle traps