Historically the design of the first EBIT prototype is connected to the name of Morton Levine and Ross Marrs. Their goal was to develop an instrument based on the principles of an earlier device called an "EBIS" (electron beam ion source) but with some fundamental improvements, allowing higher charge sates to be formed, and allowing in situ spectroscopic access to the ions. In contrast to the case for EBIS, X-ray spectroscopy was to be the primary method of studying ions produced by EBIT.
EBIT was not designed to be an ion source like its ancestor the EBIS. Since the launch of the first EBIT, however, its operation for production of very high charge states was so successful that there are now applications which are based on the extraction of ions from the machine.
After the construction of the first EBIT at Livermore, a second advance was made -- development of a high energy version of the machine. With this instrument -- usually referred to as Super EBIT -- even the highest charge states of all the elements in the periodic table are accessible. Recently the Super EBIT demonstrated production of fully stripped uranium, which has the highest atomic number among the naturally occurring elements.
The energy of the Super EBIT electron beam can be varied up to just beyond 200 keV. For most applications, however, one does not need such high electron beam energies. In fact, 40 keV is enough to theoretically strip any element to the helium-like state, and even to fully strip elements up to an atomic number of 50. Limitations on maximum obtainable current densities however make significantly higher electron beam energies desirable.
Soon after the demonstration of EBITs effectiveness, decisions were made at NIST, the Naval Research Laboratory (NRL), and Oxford University (United Kingdom) to build similar machines. The primary motivation was the possibility of doing high precision spectroscopy of highly charged ions. Due to their close proximity and long-standing previous collaboration on other spectroscopic work, NRL and NIST decided to team up to build a single EBIT for joint use in the metropolitan Washington DC area. Vacuum and internal components for both the new U.S. and U.K. machines were made in the Oxford machine shops as part of a collaboration between the institutions in the two countries.
Several physicists at the Naval Research Laboratory (NRL), Uri Feldman, Charlie Brown, George Doschek, John Seely, Bob LaVilla, and Verne Jacobs, had coauthored one of the early (1989) papers to emerge from the Livermore EBIT. While several members of that team took an NRL crystal spectrometer across the country to Livermore to help carry out the experiment, there was a growing interest in having a second EBIT facility on the East Coast to facilitate further experiments. At the time, NRL was particularly interested in solar spectra recorded by the NRL instruments on the Skylab ATM mission, the P-70-1 STP mission, and the Yohkoh Japanese satellite mission. The possibility of having a device which could create the same high ionization stages as those observed in solar spectra, but in a controlled way in the lab, was very desirable. The Solar Terrestrial Relationships Branch of the Naval Research Laboratory teamed with the Plasma Radiation Group of NIST's Atomic Physics Division to construct a new EBIT at NIST. The initiation and early planning of this was led by Dr. Jim Roberts on the NIST side and Dr. Uri Feldman on the NRL side. Dr. Charlie Brown, assisted by technician Glenn Holland, led NRL's contributions to the associated technical laboratory work, together with their NIST counterparts Dr. John Gillaspy and Mr. Douglas Alderson. NRL's Dr. Martin Laming also made significant contributions to the early development of the EBIT control system put into use at NIST.
After the early EBIT experiment at Livermore with the NRL Bragg crystal spectrometer (referred to above), this spectrometer joined its identical twin at NIST (they were originally built jointly by NIST and NRL) for use on the EBIT at NIST.
NRL's Dr. Brown supervised the development of a MeVVA which was a replica of the Berkeley group's MeVVA II design. This was carried out by Dr. Craig Boyer and Mr. Glenn Holland at NRL who built and installed the MeVVA on the NIST EBIT during the 1994 time frame. More recently, a new "Two-Wire" MeVVA design was developed completely at NRL under a joint funding collaboration with the NIST EBIT group. The new MeVVA design allows multiple cathode samples (eight different cathodes are possible) remotely selected without a vacuum break or internal vacuum motion.
The assembly of the new EBITs progressed in parallel, reaching the final phase in August of 1993 when the NIST EBIT became operational. There are already new designs and projects underway, proving the wide acceptance of the possibilities offered by the EBIT to the scientific community.
A brief listing of some milestones in the development of the NIST EBIT facility.