Results of NSTX heating experiments

• Published in: IEEE transactions on plasma science 2003-02, Vol.31 (1), p.60-67
• Main Authors: Mueller, D., Ono, M., Bell, M.G., Bell, R.E., Bitter, M., Bourdelle, C., Darrow, D.S., Efthimion, P.C., Fredrickson, E.D., Gates, D.A., Goldston, R.J., Grisham, L.R., Hawryluk, R.J., Hill, K.W., Hosea, J.C., Jardin, S.C., Ji, H., Kaye, S.M., Kaita, R., Kugel, H.W., Johnson, D.W., LeBlanc, B.P., Majeski, R., Mazzucato, E., Medley, S.S., Menard, J.E., Park, H.K., Paul, S.F., Phillips, C.K., Redi, M.H., Rosenberg, A.L., Skinner, C.H., Soukhanovskii, V.A., Stratton, B., Synakowski, E.J., Taylor, G., Wilson, J.R., Zweben, S.J., Dorland, W.D., Peng, Y.K.M., Barry, R., Bigelow, T., Bush, C.E., Carter, M., Maingi, R., Menon, M., Ryan, P.M., Swain, D.W., Wilgen, J., Sabbagh, S.A., Paoletti, F., Bialek, J., Zhu, W., Raman, R., Jarboe, T.R., Nelson, B.A., Maqueda, R.J., Wurden, G.A., Pinsker, R.I., Schaffer, M., Ferron, J., Lao, L., Stutman, D., Finkenthal, M., Wampler, W., Kubota, S., Peebles, W.A., Gilmore, M., Mau, T.K., Lee, K.C., Domier, C.W., Deng, B.H., Johnson, M., Luhmann, N.C., Bonoli, P., Bers, A., Ram, A., Akers, R., Takase, Y., Ejiri, A., Ono, Y., Shiraiwa, S., Nishino, N., Mitarai, O., Nagata, M., Yang, J.G., Na, H., Pacella, D.
• Format: Article
• Language: English
• Subjects: Applied sciences; Approximation; Confinement; Controled nuclear fusion plants; Diffusion; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fusion; Fusion reactors; Heating; Helicity; Impurities; Installations for energy generation and conversion: thermal and electrical energy; Magnetic confinement; Magnetic confinement and equilibrium; Magnetohydrodynamics; Neutral beams; Particle beam injection; Particle beams; Physics; Physics of gases, plasmas and electric discharges; Physics of plasmas and electric discharges; Plasma confinement; Plasma heating (beam injection, radio-frequency and microwave, ohmic, icr, ecr and current drive heating); Plasma production and heating; Plasma transport processes; Plasma waves; Titanium; Tokamaks; Toroidal magnetic fields; Transport
• ISSN: 0093-3813; 1939-9375
• DOI: 10.1109/TPS.2003.808890

The National Spherical Torus Experiment (NSTX) at Princeton University, Princeton, NJ, is designed to assess the potential of the low-aspect-ratio spherical torus concept for magnetic plasma confinement. The plasma has been heated by up to 7 MW of neutral beam injection (NBI) at an injection energy of 100 keV and up to 6 MW of high harmonic fast wave (HHFW) at 30 MHz. NSTX has achieved /spl beta//sub T/ of 32%. A variety of MHD phenomena have been observed to limit /spl beta/. NSTX has now begun addressing /spl tau//sub E/ scaling, /spl beta/ limits, and current drive issues. During the NBI heating experiments, a broad T/sub i/ profile with T/sub i/ up to 2 keV, T/sub i/>T/sub e/ and a large toroidal rotation were observed. Transport analysis suggests that the impurity ions have diffusivities approaching neoclassical. For L-Mode plasmas, /spl tau//sub E/ is up to two times the ITER97L L-Mode scaling and exceeds the ITER98pby2 H-Mode scaling in some cases. Transitions to H-Mode have been observed which result in an approximate doubling of /spl tau//sub E/ after the transition in some conditions. During HHFW heating, T/sub e/>T/sub i/ and T/sub e/ up to 3.5 keV were observed. Current drive has been studied using both coaxial helicity injection with up to 390 kA of toroidal current and HHFW. HHFW has produced H-modes with significant bootstrap current fraction at low I/sub p/, high q, and high /spl beta//sub p/.