- Electron beam ion trap
Electron beam ion trap (or its acronym EBIT) is used in physics to denote an
electromagneticbottle that produces and confines highly charged ions. It was invented by R. Marrs [Levine et al, 1988] and M. Levine at LLNL.
An EBIT uses an
electron beamfocused by means of a powerful magnetic field to ionize (see Ionization) by repeated electronimpact atoms injected into the apparatus to very high charge states. The vacuumdevice requires intense electron beam currents of tens up to hundreds of milliamps accelerated by means of high voltages (up to 200,000 V) applied to special electrodes. The positive ions produced in the region where the atoms intercep the electron beam are tighly confined in their motion by the strong attraction exerted by the negative charges flowing in the electron beam. Therefore, their paths orbit around the electron beam crossing it frequently, thus giving rise to further collisions and continued ionization. To keep their motion restricted in the direction of the electron beam axis, trapping electrodes carrying positive voltages with respect to the central electrode are used. The resulting ion trapcan hold the ions for many seconds and minutes, and conditions for reaching the highest charge states, up to bare uranium (U92+) are achieved in this way. To avoid spoiling the produced ions by collisions with neutral atoms from which they can capture electrons, the vacuum in the apparatus is usually maintained at UHVlevels, with typical pressure values of only 10-12 torr, (or ~10−10 pascal).
EBITs are used to investigate the fundamental properties of
highly charged ions e. g. by photon spectroscopyin particular in the context of relativistic atomic structuretheory and quantum electrodynamics(QED). Their suitability to prepare and reproduce in a microscopic volume the conditions of high temperature astrophysical plasmas and magnetic confinement fusionplasmas make them very appropriate research tools. Other fields include the study of their interactions with surfaces and possible applications to microlithography.
* Levine, M. A., et al., "The Electron Beam Ion Tr
T22, p. 157 (1988).
* Roscoe E. Marrs, Peter Beiersdorfer, and Dieter Schneider, Physics Today, 27 (October 1994)(Description of the Electron Beam Ion Trap)
* R. E. Marrs, M. A. Levine, D. A. Knapp, J. R. Henderson, Phys. Rev. Lett. 60, 1715 (1988)(First EBIT atomic spectroscopy measurement)
* R. E. Marrs, S. R. Elliott, D. A. Knapp, Phys. Rev. Lett. 72, 4082 (1994)(Production of bare uranium)
* Observation of Visible and UV Magnettic Dipole Transitions in Highly-Charged Xenon and Barium, C. A. Morgan et al., Phys. Rev. Lett. 74, 1716 (1995)
* Nanoscale modification of silicon surfaces via Coulomb explosion, H. P. Cheng, J. D. Gillaspy, Phys. Rev. B 55, 2628 (1997)
* Masked ion beam lithography with highly charged ions, J. D. Gillaspy, D. C. Parks, L. P. Ratliff,Journal of Vacuum Science and Technology B, 16, 3294 (1998)
* A new versatile electron-beam ion trap, F. J. Currell, et al., Journal of the Physical Society of Japan 65, 3186 (1996)
* H. F. Beyer, H.-J. Kluge, V. P. Shevelko, in: "X-ray Radiation of Highly Charged Ions", Springer Series on Atoms and Plasmas, Springer Verlag, Berlin-Heidelberg 1997
* [http://physics.nist.gov/MajResFac/EBIT/intro.html A brief introfuction to EBIT]
* [http://physci.llnl.gov/Research/EBIT/ Original EBIT]
* [http://physics.nist.gov/MajResFac/EBIT/intro.html#140 A list of EBIT facilities]
* [http://physics.nist.gov/MajResFac/EBIT/ebit.html Introduction to EBIT]
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