Contents: 1. Nuclear Power Development. 2. Natural Radioactivity and Radiation Exposures. 3. Neutron Reactions. 4. Nuclear Fission. 5. Chain Reaction and Nuclear Reactors. 6. Types of Nuclear Reactors. 7. Nuclear Fuel Cycle. 8. Nuclear Waste Disposal: Magnitudes of Waste. 9. Storage and Disposal of Nuclear Wastes. 10. Administrative and Policy Issues in Nuclear Waste Disposal. 11. Nuclear Reactor Safety. 12. Nuclear Reactor Accidents. 13. Reactor Safety and Future Nuclear Reactors. 14. Nuclear Energy and Weapons Proliferation. 15. Costs of Electricity from Nuclear Power. 16. The Prospects for Nuclear Power. Appendices.

Nuclear Energy: Principles, Practices, and Prospects

Collisionless damping of induced nonlinear plasma oscillations

The fast magnetosonic wave, mode converted ion cyclotron wave (MC ICW) and mode converted ion Bernstein wave (MC IBW) have all been observed and unambiguously identified in the mode conversion region of Alcator C-Mod. The influences of the species mix, mode conversion location and Bpol/Btot have been studied in D( 3 He) plasmas at B0 ∼ 5. 4T (fRF = 50 MHz) and B0 ∼ 8T (fRF = 78 MHz). The RF waves were measured by a phase contrast imaging (PCI) system. The experimental observation is compared with the result from a synthetic PCI diagnostic based upon the full wave code TORIC. Good agreement between the observation and modelling has been obtained on the spatial structure of the RF waves. When the mode conversion layer was off axis, both MC ICW and MC IBW were observed. In 5.4 T near-axis mode conversion discharges, the double hump spatial structure of the MC waves was observed experimentally and reproduced by the synthetic PCI. Such a structure is an indication of the up–down asymmetry of the MC ICW. In 8 T near-axis mode conversion discharges, we had the first definitive observation of IBW dominated MC in Alcator C-Mod. (Some figures in this article are in colour only in the electronic version)

/pdf/observation-and-modelling-of-ion-cyclotron-range-of-ujum6vllhs.pdf

Observation and modelling of ion cyclotron range of frequencies waves in the mode conversion region of Alcator C-Mod

Highly localized direct electron heating [full width at half-maximum (FWHM)≅0.2a] via mode converted ion Bernstein waves has been observed in the Alcator C-Mod Tokamak [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)]. Electron heating at or near the plasma center (r/a⩾0.3) has been observed in H(3He) discharges at B0=(6.0–6.5) T and ne(0)≅1.8×1020 m−3. [Here, the minority ion species is indicated parenthetically.] Off-axis heating (r/a⩾0.5) has also been observed in D(3He) plasmas at B0=7.9 T. The concentration of 3He in these experiments was in the range of n3He/ne≅(0.2–0.3) and the locations of the mode conversion layer and electron heating peak could be controlled by changing the 3He concentration or toroidal magnetic field (B0). The electron heating profiles were deduced using a rf modulation technique. Detailed comparisons with one-dimensional and toroidal full-wave models in the ion cyclotron range of frequencies have been carried out. One-dimensional full-wave code predictions were found to ...

Electron heating via mode converted ion Bernstein waves in the Alcator C-Mod tokamak

Radio frequency (rf) waves in the ion cyclotron range of frequencies (ICRF) are widely used for heating fusion plasmas. In a multi-ion-species plasma, the launched fast waves convert to ion cyclotron waves and ion Bernstein waves in the vicinity of the two-ion hybrid resonance between the cyclotron resonances. The mode converted waves are of interest as actuators to optimize plasma performance through current drive and flow drive. Numerical simulations are essential to describe these processes accurately in a realistic tokamak geometry, and it is important that these simulation codes be validated against experiment. The phase contrast imaging (PCI) technique has been used on Alcator C-Mod to measure directly the rf waves. The measurements were compared to predictions of full-wave simulations using a synthetic diagnostic method. The measured mode converted wave intensity was found to be a factor of ∼50 weaker than what was expected from the linear wave theory in a strong mode conversion regime. The agreement improved when the wave intensity was weaker, which is a possible indication of nonlinear wave physics being involved. Thesis Supervisor: Miklos Porkolab Title: Professor of Physics Director, Plasma Science and Fusion Center

Studies of ICRF mode conversion with phase contrast imaging and full-wave simulations in Alcator C-Mod

This thesis discusses experimental observations and the theory of mode-converted ion Bernstein waves (IBW) in the Alcator C-Mod tokamak. IBWs are short-wavelength, hot plasma oscillations that can be excited in the core of the plasma through mode conversion of an externally launched fast magnetosonic wave (FW). The balance between ion cyclotron damping of the FW and mode conversion to an IBW as a function of minority ion species concentration is explored. In the mode conversion regime, with appropriate plasma parameters, significant amounts of power can be transferred to the IBW, which can then damp on electrons, producing localized electron heating, current profile control, and current drive. Observations of electron heating in deuterium-helium-3 plasmas at 7.8 Tesla are discussed and compared to theory and full-wave code modeling. An analytic theory based on the internal resonator model [A.K. Ram, et al., Phys. Plasmas, 3, 1976 (1996)] for mode conversion compares favorably with the experimentally measured mode-conversion efficiency, as do the results of the full-wave code TORIC [M. Brambilla, Plasma Phys. Controlled Fusion, 41, 1 (1999)]. This thesis also presents direct observations of IBW oscillations, before damping takes place. Measurements are presented of the density fluctuations driven by the wave electric field near mode conversion in three ion species (hydrogen, helium-3, and deuterium) plasmas. This has been achieved with a newly upgraded Phase Contrast Imaging (PCI) diagnostic, which is now able to detect radio-frequency waves through the use of optical heterodyning. The PCI system in C-Mod measures line-integrated density fluctuations using a CO 2 laser which passes vertically through the plasma. The density fluctuation pattern is an inherently 3-dimensional structure, so the full-wave code TORIC has been used to interpret the one-dimensional measurements, which have some unexpected features, such as multiple peaks and troughs in amplitude. Strong IBW signal was often observed to the low-field side of the mode conversion layer. The importance of the parallel electric field for these IBW density fluctuation measurements is identified. IBW wavenumbers from 5 to 12 cm1 have been detected, which is within the range of the code results.

Observations and Theory of Mode-Converted Ion Bernstein Waves in the Alcator C-Mod Tokamak

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Observations and Theory of Mode-Converted Ion Bernstein Waves in the Alcator C-Mod Tokamak