Preliminary Design Considerations Research Articles

Tritium Control in NET: Preliminary Design Considerations

Tritium Control in NET: Preliminary Design Considerations

Design parameters of an unconventional probe-forming lens

The design parameters of an electron probe-forming lens with a zero-bore flat-face single pole piece have been considered under nonsaturation conditions. From the measured axial flux density distribution of an experimental single-pole-piece lens, the maximum flux density, the spherical and chromatic aberration coefficients, the focal length and the object position have been investigated in terms of the diameter of the pole's flat face, which is the effective geometrical parameter. Empirical equations relating the geometrical electron-optical parameters have been put forward and compared with those of a different experimental lens reported in the literature. The focal properties of the probe-forming lens have also been investigated in the telescopic mode of operation. The results should be useful for preliminary design considerations of an unconventional electron probe-forming lens with zero-bore flat-face single pole piece for various types of electron-optical instruments according to the operational requirements.

Preliminary design considerations for a rockbed/floor space-heating system

A solar energy house space-heating system, in which thermal energy is transferred by conduction through a concrete floor from a subfloor rockbed, is considered from the aspect of the store being able to maintain comfort conditions with no further solar energy input. The rate of decay of temperature variations along the floor is also considered. The study uses a solution of the two-dimensional diffusion equation for a composite slab subjected to a sudden change in environment: the pertinent details of the solution are given. The study shows that the interaction between the collectors, store and load is more critical in this system than in a conventional active solar-heating system. It is possible for the floor-heating system to have a storage capability which would give a system performance comparable to that for a conventional system in mild climates, but the system is less suited to more severe climates. If a phase-change material is used in the porous bed, then the bed can be very thin, but a high pressure drop and complex subfloor ductwork would need to be avoided. For thicker beds, it would be advantageous to encourage free convection within them.

Preliminary design analysis of the ALT-II limiter for TEXTOR

Installation of a large toroidal belt pump limiter, Advanced Limiter Test II (ALT-II), on the TEXTOR tokamak at Jülich, FRG is anticipated for early 1986. This paper discusses the preliminary mechanical design and materials considerations undertaken as part of the feasibility study phase for ALT-II. Since the actively cooled limiter blade is the component in direct contact with the plasma edge, and thus subject to the severe plasma environment, most preliminary design efforts have concentrated on analysis of the blade. The screening process which led to the recommended preliminary design consisting of a dispersion strengthened copper or OFHC copper cover plate over an austenitic stainless steel base plate is discussed. A 1 to 3 mm thick low atomic number coating consisting of a graded plasma-sprayed Silicon Carbide-Aluminum composite is recommended subject to further experiment and evaluation. Thermal-hydraulic and stress analyses of the limiter blade are also discussed.

Analysis and design considerations for a real-time system for non-destructive evaluation in the nuclear industry

This paper studies the feasibility of implementing a real-time system for non-destructive evaluation of nuclear reactors based on the principles of synthetic aperture processing. A detailed analysis of the computational requirements and simulation and benchmarking work on several computers seems to suggest the design of a special purpose processor as the most viable solution to the problem. The paper concludes with a discussion of the parameters affecting field design and some preliminary design considerations of the overall system.

INTOR toroidal field coil design studies

Preliminary design considerations for a toroidal field coil for INTOR with trapezoidal winding cross section, 11 T maximum field, and 2,35 kA/cm2 current density in the winding are presented. Due to severe restrictions imposed by the INTOR specifications meeting the allowable stress level is a big challenge for the designer.

Solar storage systems using salt hydrate latent heat and direct contact heat exchange—I preliminary design considerations

The operating characteristics of a salt hydrate latent heat storage system, using Glauber's salt and direct contact heat exchange through an immiscible heat transfer fluid, have been studied theoretically. Drop dynamics and heat transfer models from the literature were used to predict the system behaviour for a range of conditions involving heat transfer fluid inlet temperature and drop size, composition and crystallization temperature of the salt and vessel contact height. The results of these calculations are used to guide the specification of an approx. 1 10 scale pilot heat storage unit which has been constructed and operated successfully.

The fluid mechanics of pulsed laser propulsion

A fluid mechanical model is developed to assess the performance of a rocket that is propelled by the absorption of radiant energy from a remotely stationed, repetitively pulsed laser. The model describes the flow within a conical nozzle that is subjected to point energy depositions at the apex of the cone. A similarity solution is obtained and the specific impulse and energy efficiencies that may be achieved with such a device are determined. Fluid mechanical constraints limit the range of pulse repetition rates that may be utilized. Preliminary design considerations indicate that a specific impulse of 800 sec or greater may be achieved with both a laboratory and a full-scale device. A two pound laboratory rocket can be accelerated at 10 #'s with a 15 joule laser pulsed 25,000 times per sec. A one ton rocket will require a megajoule laser operating at 350 pulses per sec to achieve an equivalent acceleration. A,a D* dm

The Fluid Mechanics of Pulsed Laser Propulsion

A fluid mechanical model is developed to assess the performance of a rocket that is propelled by the absorption of radiant energy from a remotely stationed, repetitively pulsed laser. The model describes the flow within a conical nozzle that is subjected to point energy depositions at the apex of the cone. A similarity solution is obtained and the specific impulse and energy efficiencies that may be achieved with such a device are determined. Fluid mechanical constraints limit the range of pulse repetition rates that may be utilized. Preliminary design considerations indicate that a specific impulse of 800 sec or greater may be achieved with both a laboratory and a full-scale device. A two pound laboratory rocket can be accelerated at 10 #'s with a 15 joule laser pulsed 25,000 times per sec. A one ton rocket will require a megajoule laser operating at 350 pulses per sec to achieve an equivalent acceleration. A,a D* dm

Preliminary design considerations of a high performance Hall-currentaccelerator.

Details of the analysis for predicting space storability are presented in Ref. 2. Briefly, the major source of deviations between experimental results and predicted results is examined recognizing the fact that the analytical and experimental results tend to converge as the tank size increases. Results can then be extrapolated to cryogenic propellants other than LN2. Typical results of this analysis are shown in Fig. 7. Losses of propellants other than hydrogen are acceptable for the tank sizes shown. The long-term storage of hydrogen becomes practical with tank diameters >15 ft. This work has shown that heat leaks to cryogenic tanks are due mainly to penetrations of the insulation of supports and propellant lines to the erigine(s). Only 27% of the heat flow to the 8-ft spherical tank occurs directly through the insulation. A significant development effort to reduce heat leakage through penetrations is needed. The development of a re tractable support system bears strong consideration. The effects of a zero-gravity environment on venting and on heat-transfer coefficients, and the heat input from the pressurization system gas, were not considered because of program limitations. These areas are currently being investigated bv the AFRPL. The effect of the ground launch environment on the performance of the superinsulation of a hydrogen tank is currently being investigated by NASA and will affect the results presented for hydrogen storability.

Predicting the Effective Dynamic Coupling Coefficient of the Flextensional Transducer (Preliminary Design Considerations)

Expressions for the effective dynamic coupling coefficient of the flextensional transducer have been approximated. The approximate solutions are illustrated and compared with experimental data.

Nuclear Radiation Heating: Preliminary Design Considerations

Quick engineering estimates of nuclear radiation heating effects exterior to reactors are frequently desired in preliminary flight vehicle design. A technique that is useful for such evaluations is presented. Analogies are suggested among the capture, inelastic scattering and neutron-induced charged particle processes; a means is provided for treating neutron interactions giving rise to gamma rays of various discrete energies; and a cosine distribution of the core gamma radiation is discussed.