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Can hydrogen be the transportation fuel in an otherwise nuclear economy?
Let’s face it: The global economy should be powered primarily by nuclear power. And it probably will by the end of this century, with a still-significant assist from renewables and hydro. Once nuclear systems are dominant, the costs come down to where gas is now; and when carbon emissions are reduced to a small portion of their present state, it will become obvious that most other sources are only good in niche settings. I mean, why use small modular reactors to load-follow when they can just produce that power instead of buffering it?
P. A. Politzer
Fusion Science and Technology | Volume 48 | Number 2 | October 2005 | Pages 1170-1177
Technical Paper | DIII-D Tokamak - Radio-Frequency Heating and Current Drive | doi.org/10.13182/FST05-A1069
Articles are hosted by Taylor and Francis Online.
Noninductive current drive is an essential part of the implementation of the DIII-D Advanced Tokamak program. For an efficient steady-state tokamak reactor, the plasma must provide close to 100% bootstrap fraction (fbs). For noninductive operation of DIII-D, current drive by injection of energetic neutral beams [neutral beam current drive (NBCD)] is also important. DIII-D experiments have reached ~80% bootstrap current in stationary discharges without inductive current drive. The remaining current is ~20% NBCD. This is achieved at N [approximately equal to] p > 3, but at relatively high q95 (~10). In lower q95 Advanced Tokamak plasmas, fbs ~ 0.6 has been reached in essentially noninductive plasmas. The phenomenology of high p and N plasmas without current control is being studied. These plasmas display a relaxation oscillation involving repetitive formation and collapse of an internal transport barrier. The frequency and severity of these events increase with increasing , limiting the achievable average and causing modulation of the total current as well as the pressure. Modeling of both bootstrap and NBCD currents is based on neoclassical theory. Measurements of the total bootstrap and NBCD current agree with calculations. A recent experiment based on the evolution of the transient voltage profile after an L-H transition shows that the more recent bootstrap current models accurately describe the plasma behavior. The profiles and the parametric dependences of the local neutral beam-driven current density have not yet been compared with theory.