Neutral beam injector research and development work in the USA Page: 3 of 8
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A first model of a fractional area, MFTF/DIII 80 kV source has been
operated with 80 kV, 14 A, 0.5-sec pulses. No basic problems 'ith the
source designs have shown up; full-scale module tests will start soon.
(The overall design and construction of the full-scale MFTF source has
been carried out by MFTF personnel.)
The second part of our program is devoted to development for longer-
term applications. The next few years will be devoted to increasing effi-
ciency (ion species, gas, electrical), pulse length, energy (to 150 kV),
and reliability. All of these items require major advances over present
As part of this program we are developing a new generation of
plasma sources with improved ion and electron confinement by cusp magnetic
fields at the walls. These sources should have improved electrical effi-
ciency and should produce ion beams with an enhanced atomic ion fraction.
We are also developing the technology necessary for direct recovery of the
energy of that portion of the beam which remains un-neutralized. The ex-
periments to date, carried out with a 1 kW, 15 keV steady-state beam, gave
70% recovery efficiency. Electrostatic as well as magnetic fields were used
for electron suppression. Recovery of a single species 10 keV H+ beam us-
ing magnetic electron suppression gave over 85% recovery efficiency. Scaled
up experiments on a 50 kW, 105 keV beam is underway with recovery effici-
ency over 20% initially, but decaying during the 500 msec pulse. The col-
lector self-biased to a voltage over 75 kV. In the area of long-pulse op-
eration, we are developing cathodes with d.c. capability, and have under-
taken a computational analysis of secondary particle trajectories in the
accelerator structure, which, together with experimental measurements,
should permit us to identify and reduce the dominant heating mechanisms.
We aie developing, through industrial vendors, techniques for manufac-
turing sources that are to be entirely hard sealed. Recently, a method
for brazing rectangular ceramic insulators to metal electrodes has been
developed at LBL for use on the ion accelerators for TFTR. 
New approaches to the design of electronics  and computerized con-
trols  are included in the program.
2.2 ORNL Neutral Beam Work
The ORNL Plasma Technology Section participates in a variety of
fusion pl-ama heating activities. Neutral beam injection systems have been
designed for use on several state of the art tokamaks (PLT,  ISX, 
PDX, LPT and TNS). The development and qualification of four PLT inject'.n
systems was recently completed with operating parameters of 0.75 MW (1 M)
neutral beam power per injector utilizing hydrogen (deuterium) extraction.
initial operation of two (four systems are installed on PLT) of these sys-
tems at about 1 MW neutral power produced record tokanak ion temperatures
of about 2.3 keV.
ISX and PDX ion sources have been operated at plasma parameters con-
sistent with 100 A extraction. A complete 100 A source is being assembled.
The PLT injection system has been upgraded in pumping and will transport
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Pyle, R.V.; Baker, W.R. & Barr, W.L. Neutral beam injector research and development work in the USA, article, July 1, 1978; Berkeley, California. (https://digital.library.unt.edu/ark:/67531/metadc1182193/m1/3/: accessed April 20, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.