Fusion proton diagnostic for the C-2 field reversed configuration
R. M. Magee · R. Clary · S. Korepanov · A. Smirnov · E. Garate · K. Knapp · A. Tkachev
Summary and citation · read the original at the source · none found
In one page
Tri Alpha Energy — the California company now called TAE Technologies — built its C-2 machine to hold a field reversed configuration, a plasma that makes its own magnetic bottle out of its own circulating current. Richard Magee and six colleagues describe a new instrument for reading what happens inside it. When two deuterium nuclei fuse they sometimes produce a proton of about three million electronvolts, and because the fusion rate climbs steeply with ion energy, counting those protons is an unusually sensitive way to measure how energetic the ions are. Their detector is a large silicon diode, fifty square centimetres, run so that every arriving proton registers as one countable pulse. The scintillator neutron detectors already on the machine are fast but positionally blind. This one resolves ten centimetres along the machine, which is exactly what is needed to test whether the fast ions injected by the neutral beams settle where classical theory says they should, or whether some other scattering mechanism is at work. The paper closes with first data from a neutral beam test chamber.
Why it matters hereChapter 9 is about self-organised plasmoids, and the field reversed configuration is the laboratory version of one: a plasma ring that holds its own shape with its own currents. Chapter 12 is about getting fusion out of a confined system, and this is the instrument that tells you whether the fast ions are behaving — the measurement that has to work before any claim about confinement or gain can be trusted.
What it claims
01Measurements of the flux of fusion products from high temperature plasmas provide valuable insight into the ion energy distribution, because the fusion reaction rate is a very sensitive function of ion energy. That steep dependence is what makes counting fusion products a thermometer rather than merely a tally.Abstract, first sentence
Settled physics02In C-2, field reversed configuration plasmas are formed by the collision of two compact toroids and are partially sustained by high power neutral beam injection — the architecture reported by Binderbauer and colleagues in Physical Review Letters 105, 045003 (2010) and by Tuszewski and colleagues in Physical Review Letters 108, 255008 (2012).Abstract, second sentence, with the two Physical Review Letters citations it carries
Published and peer-reviewed03Measurements of the deuterium-deuterium fusion neutron flux are already used on C-2 to diagnose ion temperature and to study fast ion confinement and dynamics.Abstract, second sentence
Published and peer-reviewed04The new instrument is a 3 MeV proton detector built to complement the existing neutron detectors: a large area, fifty square centimetre, partially depleted, ion implanted silicon diode operated in a pulse counting regime.Abstract, third and fourth sentences
On the bench now05The scintillator-based neutron detectors allow high time resolution of about 100 kHz but have no spatial or energy resolution; the proton detector supplies 10 cm spatial resolution instead.Abstract, fifth and sixth sentences
On the bench now06What to watch is the measurement the detector was built to make: whether the axial distribution of fast ions is consistent with classical fast ion theory, or whether anomalous scattering mechanisms are active. The paper presents the diagnostic design and initial data from a neutral beam test chamber; the answer comes from the machine.Abstract, sixth and final sentences
What to watch
The way in
https://doi.org/10.1063/1.4892861SOURCE NOT REACHED IN FULL. The article is held closed by AIP: OpenAlex, Unpaywall and Semantic Scholar all report oa_status closed with no repository copy anywhere, checked 2026-09-08. So the summary and every claim below are written from the authors’ own abstract as deposited by AIP and read through the Crossref record, and from the bibliographic record itself — Review of Scientific Instruments volume 85, issue 11, article 11D851, published 1 November 2014, with all seven authors listed at Tri Alpha Energy, Inc., Rancho Santa Margarita, California, the company now trading as TAE Technologies. Locators therefore point to sentences of the abstract rather than to numbered sections, and no text of the article is reproduced here.
How to cite it
R. M. Magee, R. Clary, S. Korepanov, A. Smirnov, E. Garate, K. Knapp, A. Tkachev (2014) Fusion proton diagnostic for the C-2 field reversed configuration. doi:10.1063/1.4892861
Where it sits in the curriculum
Plasmoids, charge clusters and the orbsLattice confinement fusion