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Fusion energy: Progress, partnerships, and the path to deployment
Over the past decade, fusion energy has moved decisively from scientific aspiration toward a credible pathway to a new energy technology. Thanks to long-term federal support, we have significantly advanced our fundamental understanding of plasma physics—the behavior of the superheated gases at the heart of fusion devices. This knowledge will enable the creation and control of fusion fuel under conditions required for future power plants. Our progress is exemplified by breakthroughs at the National Ignition Facility and the Joint European Torus.
S. C. Chiu, V. S. Chan
Fusion Science and Technology | Volume 18 | Number 4 | December 1990 | Pages 591-596
Alpha Particles in Fusion Research | doi.org/10.13182/FST90-A29251
Articles are hosted by Taylor and Francis Online.
Fast-wave current drive presents a promising scheme for steady-state operation of reactor tokamaks. This scheme is being studied for application in the International Thermonuclear Experimental Reactor (ITER), the Joint European Torus (JET), and the Doublet III-D reactor (DIII-D). There are two regimes that appear to be promising, the low-frequency range 0 < ω < 2ΩD and the lower hybrid frequency range ΩD ≪ ω < ωLH. In the latter scheme, the wavelength of the fast wave becomes much shorter than the alpha-particle gyroradius and alpha-particle absorption can become significant. An analytic formula for alpha-particle absorption of fast waves for the standard slowing down distribution has been derived and compared with electron absorption at ITER parameters. It has been found that at TD > 30 keV and ne ∼ 1014 cm−3, the alpha-particle absorption is large and can greatly decrease the current drive efficiency. However, without sacrificing the fusion reactivity rate, by increasing the density and decreasing the temperature 15 keV < TD < 25 keV, the alpha-particle absorption can become small at a sufficiently high frequency. It is suggested that a simulation of the alpha-particle absorption effect on fast-wave current drive can be made in DIII-D by using a lower frequency source (∼30 MHz) to create a minority tail and a high-frequency source (200 MHz) to drive the current. Results of minority absorption are presented. Effects that can improve current drive efficiency are discussed.