[en] The regimes of thermonuclear burning in selfsustained and driven tokamak reactors using deuterium-tritium plasma with nuclei polarized along the magnetic field are investigated. A comparison is made between the burning regimes in reactors with polarized and unpolarized plasma. In particular, it is shown that the temperature regions that allow stable steady-state thermonuclear reactions are similar for both types of reactors. However, as compared to the conventional case, the driven reactor with polarized nuclei requires higher power levels of neutral injection or radiofrequency heating to achieve the same stable temperature regime. The power multiplication factor, when using polarized nuclei, is unchanged or may be higher due to deterioration of alpha-particle confinement

[en] A design of a prototype moving-ring reactor was completed, and a development plan for a pilot reactor is outlined. The fusion fuel is confined in current-carrying rings of magnetically field-reversed plasma (''compact toroids''). The plasma rings, formed by a coaxial plasma gun, undergo adiabatic magnetic compression to ignition temperature while they are being injected into the reactor's burner section. The cylindrical burner chamber is divided into three ''burn stations.'' Separator coils and a slight axial guide field gradient are used to shuttle the ignited toroids rapidly from one burn station to the next, pausing for one-third of the total burn time at each station. Deuterium-tritium-³He ice pellets refuel the rings at a rate that maintains constant radiated power. The fusion power per ring is approx. =105.5 MW. The burn time to reach a fusion energy gain of Q = 30 is 5.9 s

[en] Inductive formation and sustainment of spheromaks are examined. The S-1 device utilizes a flux core to form a spheromak inductively. Plasmas are observed to relax during formation toward a minimum energy state, independent of initial conditions. Inductive sustainment of spheromaks is considered possible by utilizing this relaxation process. One method uses a poloidal flux transformer along the major axis, similar to the ohmic heating transformer in a tokamak. Alternatively, spheromaks can be established with the outermost poloidal field lines linked around the flux core to provide coupling between the plasma and external circuits. The spheromak configuration then can be sustained by oscillating the currents in the poloidal and toroidal field coils within the flux core. These proposed current drive schemes are investigated using the concept of magnetic helicity injection

[en] A study of a conceptual design for a ''cassette'' compact toroid reactor has been performed that emphasizes quick replacement handling. The core plasma, spheromak, is ohmically heated in a merging process between the core plasma and the gun-produced spheromak. The quick handling of replacement accomplished by using a functional material, a shape memory alloy (SMA) joint, which is proposed for release from first-wall high neutron loading in a newly devised mechanical and structural method. The SMA joint can be used for connecting or disconnecting the coupling by simply controlling the SMA temperature without the need for a robot system. Effective heat removal from the first wall and thermal and electromagnetic stress in a fusion core with very high heat flux are discussed from an engineering standpoint

[en] Compositional changes in the surface region of single-crystal SiC(0001) due to heat treatment and light ion irradiation in the keV range were studied with the use of AES. The heat treatment at 1000⁰C formed a carbon enriched layer with a thickness of 20 A on the top surface and a carbon depletion layer below this layer. Both hydrogen and helium ion irradiation caused depletion of silicon atoms in the near surface region and depletion of carbon atoms in the deeper surface region. TRIM computations revealed that in the process of slowing down of incident hydrogen ions, their kinetic energy was transfered preferentially to silicon atoms in the near surface region and to carbon atoms in the deeper surface region. This tendency explains the formation of each altered layer

[en] Fusion breeders are fusion reactors designed specifically to produce fissile fuel for fission reactors such as the light water reactor (LWR). Two kinds of fusion breeders are reviewed. The first uses a blanket designed to multiply neutrons by fissioning the abundant isotopes of ²³⁸U and ²³²Th. This design is predicted to produce enough fissile fuel for four or more LWRs and produces so much energy in the blanket that fusion performance can be reduced to a level technologically feasible within the next 10 to 15 yr. The second kind of fusion breeder uses a blanket designed to suppress fission, which enhances safety by the nonfissioning multiplication of neutrons in beryllium. This fission-suppressed fusion breeder is predicted to produce enough fissile fuel for ten or more LWRs of equal thermal power. Either kind of fusion breeder has the potential to provide a source of reasonably priced fissile fuel after the low-cost natural uranium fuel supply is gone. The suppressed-fission-type fusion breeder could enable conventional nuclear plants to be expanded to 50% of the US electrical capacity by the year 2050, if necessary. Despite the high development risk associated with fusion technologies, it appears that the potential advantages of the fusion breeder could be great enough to warrant an increase in research effort to the level required to determine its feasibility for commercial application and to ensure its availability for commercial application and to ensure its availability when needed, provided that there is clear evidence of an increase in US demand for fission power, as evidence by new reactor orders. 33 references, 4 figures, 2 tables

[en] The n = 2 mode rotational instability, which appears on a field-reversed configuration plasma produced by a theta pinch, is stabilized by a helical quadrupole field. The critical strength of the field to stabilize the instability is obtained as a function of pitch angle of the helical coil α rad/m. Typically, the plasma in the α = 6 winding field is stabilized by about one-fifth of α = 0 field strength. To physically explain such a good effectiveness of the helical field, the rotation speed of the plasma is measured by a Doppler shift of a carbon V 2270.9-A line. However, the clear explanation to the helical effect is not yet given

[en] Experiments on fusion reactions produced by adiabatic compression of plasma vortex structures are discussed. The TRISOPS machine at the University of Miami has been modified by improving the preionization of the plasma and increasing the ring frequency of the conical theta-pinch coils. The results obtained with a series of experiments leading up to the latest machine, TRISOPS VIII, are reviewed. It has been possible, with this modified machine, to obtain ion temperatures of 1 keV before secondary magnetic compression without any magnetic guide field. Ion temperatures of over 6 keV are obtained with secondary magnetic compression fields of 30,000 G. The plasma pressure, in both instances, must be balanced by hydrodynamic forces. Ion temperatures and densities were measured by three different methods. All methods yield essentially the same results. The plasma was held in stable equilibrium for 30 μs and neutrons were produces for 40 μs

[en] A compact fusion reactor design with magnetic confinement based on a field-reversed configuration is described. The reactor is linear and operates in a pulsed mode where the plasma moves as a translating ''plasmoid'' through the burn chamber. The plasma physics model incorporates recent theoretical and experimental results on confinement. The design is compact and its power output is limited by first-wall and blanket technology. A helium-cooled solid breeder blanket is used for tritium breeding and thermal energy removal. A graphite thermal shield is included to reduce the energy generation and resulting first-wall stresses during pulsed operation. These studies indicate that attractive designs in the range of 300 to 1000 MW(electric) are possible, provided that currently understood scaling laws extrapolate favorably into the reactor regime. Multidimensional neutronics analysis indicates tritium breeding ratios >1.0

[en] The effects of producing a net toroidal current in the Fusion Engineering Device (FED-A) by using an input magnetosonic (or fast) wave to modify the alphaparticle velocity distribution function through momentum transfer via the transit time damping process are studied. The alpha-particle distribution becomes anisotropic, producing a net current through collisions with the background electrons. The fast wave is found to be accessible, and resonances at cyclotron harmonics and the ion-ion hybrid layer can be minimized by choosing ω about 4ω /sub CD/ , where ω /sub CD/ is the deuterium cyclotron frequency. The calculation is based on an alpha-particle velocity distribution function accounting for slowing down against the background plasma electrons. The efficiency of the process is found to compare favorably with lower hybrid current drive, but the magnitude of the induced current falls short of the FED-A design current with the assumed value of the wave parallel magnetic field