Plasma and Fusion Research
Volume 13, 3402121 (2018)
Regular Articles
- 1)
- SOKENDAI (The Graduate University for Advanced Studies), Toki, Gifu 509-5292, Japan
- 2)
- National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Gifu 509-5292, Japan
- 3)
- Kyoto University, Kyoto 615-8540, Japan
Abstract
The deuterium plasma experiments have been conducted since March 2017 on the Large Helical Device. The neutron yield per shot has reached up to 7 × 1014 and 3.5 × 1015 in the first phase where NBI #1, 2, and 3 used hydrogen and NBI #4 and 5 used deuterium, and in full D-D phase, respectively. For the triton burnup study in this campaign, the neutron activation system (NAS) has been used to measure 14 MeV neutrons and 2.45 MeV neutrons. The triton burnup ratio of 0 ∼ 0.34% are obtained by the NAS measurement. Triton burnup ratio increases with electron density when line-averaged electron density is below about 2.5 × 1019 m−3, and decreases with electron density above 2.5 × 1019 m−3. Meanwhile, the triton burnup ratio decreases as the magnetic axis positions shift outward, which can likely be explained by the orbit of helically trapped energetic tritons. In addition to the NAS measurement, the phenomenon of the 14 MeV neutron emission lagging at the 2.45 MeV neutrons emission has been observed by the time evolution measurement with scintillating-fiber detectors and neutron flux monitor.
Keywords
triton burnup, LHD, neutron activation, 14 MeV neutron, alpha confinement
Full Text
References
- [1] A. Iiyoshi et al., Nucl. Fusion 39, 1245 (1999).
- [2] M. Isobe et al., Rev. Sci. Instrum. 85, 11E114 (2014).
- [3] N. Pu et al., Rev. Sci. Instrum. 88, 113302 (2017).
- [4] M. Isobe et al., Rev. Sci. Instrum. 81, 10D310 (2010).
- [5] L.C. Johnson et al., Rev. Sci. Instrum. 66, 894 (1995).
- [6] C.W. Barnes et al., Rev. Sci. Instrum. 61, 3190 (1990).
- [7] C.W. Barnes et al., Nucl. Fusion 38, 597 (1998).
- [8] S. Conroy et al., Nucl. Fusion 28, 2127 (1988).
- [9] M. Hoek et al., “Triton burnup measurements at ASDEX Upgrade by neutron foil activation”, IPP-Report IPP-1/320 (1999).
- [10] M. Hoek et al., Nucl. Instrum. Methods Phys. Res. A 368, 804 (1996).
- [11] H.H. Duong and W.W. Heidbrink, Nucl. Fusion 33, 211 (1993).
- [12] P. Batistoni et al., Nucl. Fusion 27, 1040 (1987).
- [13] W.W. Heidbrink, R.E. Chrien and J.D. Strachan, Nucl. Fusion 23, 917 (1983).
- [14] J. Jo et al., Rev. Sci. Instrum. 87, 11D828 (2016).
- [15] N. Pu et al., Rev. Sci. Instrum. 89, 10I105 (2018).
- [16] T.H. Stix, Plasma Phys. 14, 367 (1972).
- [17] S. Murakami et al., J. Plasma Fusion Res. SERIES 5, 620 (2002).