A comparison matrix decision model is applied to candidates for a D-T ignition tokamak (TNS), including assessment of semi-quantifiable or judgemental factors as well as quantitative ones. The results show that TNS is mission-sensitive with a choice implied between near-term achievability and reactor technology.

Here a more detailed publication is summarized which presents analytical methods with solutions that describe the structural behavior of ohmic heating solenoids to achieve a better understanding of the relationships between the functional variables that can provide the basis for recommended design improvements. The solutions relate the requirements imposed by structural integrity to the need for producing sufficient flux swing to initiate a plasma current in the tokamak fusion machine. A method is provided to perform a detailed structural analysis of every conducting turn in the radial build of the solenoid, and computer programmed listings for the closed form solutions are made available as part of the reference document. Distinction is made in deriving separate models for the regions of the solenoid where turn-to-turn radial contact is maintained with radial compression or with a bond in the presence of radial tension, and also where there is turn-to-turn radial separation due to the absence or the loss of bonding in the presence of would be radial tension. The derivations follow the theory of elasticity for a body possessing cylindrical anisotropy where the material properties are different in the radial and tangential directions. The formulations are made practical by presenting the methods …

The toroidal field coils in two of the four TNS field coil design options are superconducting. NbTi superconductors are used in the low field design option and Nb/sub 3/Sn superconductors are used in the high field design option. The preliminary conceptual design parameters of the coils and the superconductors have been developed. The selected coil shape is the pure tension D-configuration. The superconductors are the multifilamentary, cabled design and are cooled by forced flow supercritical helium. Thermal stability analyses were performed for the superconductors. The cryogenic recovery capability of the NbTi superconductors is more than 10/sup 5/ J/m/sup 3/ of conductor plus helium volume and that of the Nb/sub 3/Sn is more than 3 x 10/sup 5/ j/m/sup 3/.

The matrix isolation spectra of all of the 40 presently known atomic metal species show strong matrix effects. The transition energies are increased, and the bands are broad and exhibit splitting of sublevels which are degenerate in the gas phase. Several models have been proposed for splitting of levels, but basic effects are not yet understood, and spectra cannot be predicted, yet it is possible to correlate gas phase and matrix in many of the systems. Selective production of diatomics and clusters via thermal and optical annealing of atomic species can be monitored by optical spectra, but yields spectroscopically complex systems which, however, especially in the case of transition metals, can be used as precursors in novel chemical reactions. A combination of absorption, emission, ir, Raman, ESR, and other methods is now quickly yielding data which will help correlate the increasing wealth of existing data. 55 references, 6 figures.

Conditions for the stable propagation of a pinched electron beam in low pressure gas (p approximately 0.1 to 100 torr) are described. The observed window of good propagation around p approximately 2 torr air is interpreted as the quenching of the two-stream mode by sufficiently high plasma density and collision frequency, and the simultaneous suppression of the resistive hose mode by sufficiently rapid generation of electrical conductivity from breakdown ionization.

The magnetic, structural, and thermal design of superconducting poloidal field coils for a tokamak fusion-fission breeder reactor are described. The design requirements and considerations, with the resulting parameters, are presented.

A model of the interaction between an ignited plasma and a wall is utilized to study the impact of impurities and recycled fuel ions and helium ash on the burn time of the plasma. The model indicates that the impurity concentration, n/sub im/, grows exponentially toward a maximum value determined by the confinement time for impurities, tau/sub im/, the sputtering coefficient, S/sub i/, and the isolation coefficient, ..cap alpha... The time for n/sub im/ to reach a critical value and quench the plasma was determined for representative impurities, C, Mo, W, Fe, under various conditions of plasma temperature. Methods for extending the burn time by minimizing the effective sputtering coefficient of the wall and increasing the isolation of the plasma from the wall are reviewed. The carbides, B/sub 4/C and SiC, are found to have encouraging sputtering properties but their thermal, chemical and mechanical properties need to be evaluated before they can be recommended for use as first walls. The magnetic divertor is the preferred isolation scheme. Because the divertor carries impurities and leaked fuel and helium ions to a burial chamber, required pumping speeds are found to be very high for TNS plasmas and supplemental particle trapping systems must …

The electrical design of the ORNL-Westinghouse next step (TNS) fusion reactor was begun in 1976, using a set of ground rules which were based on the overall program objectives. These objectives were to identify the design of reasonably-priced reactors, which would achieve ignition and be technology forcing. The term ''technology forcing'' was understood to mean the desirability of a large number of ignited D-T pulses and the incorporation of superconducting toroidal field (TF) coils, if at all possible. A trade study methodology was developed to compare different machine sizes and TF coil technologies and to aid in the selection of system and subsystem design approaches. The logic which led from the program objectives to the design ground rules and from the ground rules to the circuit selection is described below. The circuit design approaches were generalized and these models were incorporated into a computer program (COAST) which was used to examine the cost of overall tokamak systems as key design parameters were varied.

A FORTRAN code for the COsting And Sizing of Tokamaks (COAST) is described. The code was written to conduct detailed analyses on the engineering features of the next tokamak fusion device following TFTR. The ORNL/Westinghouse study of TNS (The Next Step) has involved the investigation of a number of device options, each over a wide range of plasma sizes. A generalized description of TNS is incorporated in the code and includes refined modeling of over forty systems and subsystems. Considerable detailed design and analyses have provided the basis for the thermal, electrical, mechanical, nuclear, chemical, vacuum, and facility engineering of the various subsystems. Currently, the code provides a tool for the systematic comparison of four toroidal field (TF) coil technologies allowing both D-shaped and circular coils. The coil technologies are: (1) copper (both room temperature and liquid-nitrogen cooled), (2) superconducting NbTi, (3) superconducting Nb/sub 3/Sn, and (4) a Cu/NbTi/ hybrid. For the poloidal field (PF) coil systems copper conductors are assumed. The ohmic heating (OH) coils are located within the machine bore and have an air core, while the shaping field (SF) coils are located either within or outside the TF coils. The PF coil self and mutual inductances are …

This paper gives an in-depth discussion on the various methodologies currently available to predict the near-field ground motion from an earthquake. The limitations of the various methods are discussed in some detail in light of recently available data. It is shown that, (at least for California earthquakes) for an earthquake with a given magnitude a wide variation in the peak ground motion can occur. The change in the spectral content of the ground motion is given as a function of earthquake magnitude and peak ground acceleration. It is shown that the large g values associated with small earthquakes are relatively unimportant in the design provided the structures have a modest amount of ductility. Data recently obtained from the Friuli earthquake are also examined. Although not all the geophysical data are currently available, the provisional conclusion is reached that the relation between the strong ground motion from this earthquake and its source parameters is the same as for the western United States.

Tritium breeding in a fusion-fission tokamak reactor is optimized by the technique of geometric programming. The neutronic processes are represented as an objective function found by fitting a generalized quadratic function of the zone widths to the breeding ratio found from planned computational experiments. The results of this technique are examined, and the predicted performance compared to neutronic calculations with the optimized values of the design variables.

An Intense Pulsed Ion Neutral Source (IPINS) is being developed for injection into a mirror confinement experiment. The ion source is based on the reflex triode principle. The parameters achieved in current small-scale experiments are pulse duration 1 ..mu..s, beam energy 80 keV, and ion current density approximately 0.2 kA/cm/sup 2/. Beam neutralization using thin carbon foils is under investigation.

The long range imaginary optical potential arising from quadrupole Coulomb excitation is derived in closed form. An analytical closed form for elastic scattering is obtained by inserting this potential into a weak absorption modified form of Frahn's strong absorption model.

The ORNL/Westinghouse program for The Next Step (TNS) tokamak beyond TFTR has examined a large number of potential configurations for D-T burning ignition tokamak systems. An objective of this work has been to quantify the trade-offs associated with the assumption of certain plasma physics criteria and toroidal field coil technologies. Four tokamak system point designs are described, each representative of the TF coil technologies considered, to illustrate the engineering features associated with each concept. Point designs, such as the ones discussed herein, have been used to develop component size, performance and cost scaling relationships which have been incorporated in a digital computer code to facilitate an examination of the total design and cost impact of candidate design approaches. The point designs which are described are typical, however, they have not been individually optimized. The options are distinguished by the TF coil technology chosen and include: (1) a high field water-cooled copper TF system, (2) a moderate field NbTi superconducting TF system, (3) a high field Nb/sub 3/Sn superconducting TF system, and (4) a high field hybrid TF system with outer NbTi superconducting windings and inner water-cooled copper windings. Descriptions are provided for the major device components and all major support …

This report addresses a compact poloidal divertor reference design for TNS.

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