Visible light emitted by highly charged ions in electron-beam ion trap

March 1, 1995

Scientists at the National Institute of Standards and Technology (NIST, Gaithersburg, MD) have detected visible light from highly charged ions held in an electron-beam ion tra¥(EBIT). This device strips most of the electrons from atoms, producing and trapping highly compact forms of matter such as hydrogen- and helium-like atoms with masses 100 times larger than ordinary hydrogen. Previous emissions from such ions in an EBIT have been detected only in the x-ray region.

Using barium and xenon atoms, NIST researchers verified that highly charged ions in an EBIT could produce visible emission under certain conditions. Says project leader John Gillaspy, "The truly remarkable thing about these emissions is that they are predicted to remain visible for isoelectronic charge states that span the entire upper half of the periodic table--it is as if the ordinary wavelength scaling laws have broken down. This should make them very practical for use in the next generation of Tokamak fusion devices."

The electron beam of the EBIT removes electrons, trapping the resultant ions and causing them to undergo a transition to an excited state. Ions producing the visible emission have a lifetime on the order of a millisecond and produce deep-blue light near 400 nm. The charge state and other conditions are similar to those found in Tokamak fusion reactors, providing scientists with a tool for reactor study that could lead to improvements in efficiency. Researchers will be searching for visible emission from titanium-like ions in operational fusion test reactors, and expect to gain insights into ion behavior in fusion reactors.