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Kinetic inductance measurements in linear circular and rectangular cylindrical superconductors, giving inductance temperature dependence for wires and both thick and thin films
A theory is described for the production of electric currents in the magnetosphere and for the transfer of energy from the solar wind to the magnetosphere. Assuming that the magnetosheath has ohmic-type conduction properties, it is shown that unipolar induction can energize several current flows, explaining the correlation of the east-west component of the interplanetary magnetic field with polar electric fields and polar magnetic variations. In the tail region, unipolar induction can account for effects correlated with the north-south component of the interplanetary magnetic field.
Hypothermia was induced in the golden hamster Mesocricetus auratus, using the helium-cold method. The first group of hamsters was sacrificed immediately after induction to rectal temperature 7 C, a second group was sacrificed after being maintained at a body temperature of 7 C for 18-24 hr, and a third group consisted of unexposed controls. The hearts were excised and the ventricles analyzed for hypoxic damage, glycogen, and catecholamines. In the short-term hypothermic animals, resting tension was increased while peak isometric tension, generated tension after 10 min of anoxic exposure, glycogen, and catecholamines were all reduced. All of the functional parameters recovered in the long-term hypothermic group, while glycogen and catecholamines showed a trend toward recovery. It is concluded that myocardial hypoxia develops during induction into hypothermia when using the helium-cold method. This effect is reversible and hypoxic damage does not increase as the hypothermic exposure is prolonged.
The design and construction of inductive transducers for measuring the vibrations in metal bars at ultrasonic frequencies are discussed. Illustrations of the inductive transducers are provided. The quantitative relations that are useful in designing the transducers are analyzed. Mathematical models are developed to substantiate the theoretical considerations. Results obtained with laboratory equipment in testing specified metal samples are included.
An extensive test program was undertaken to determine the effect of many design features such as the size and number of air scoops, and the type of diffuser airflow distribution to use to optimize performance of a double-annular ram-induction combustor of 94 cm outer diameter. Six combustor configurations were tested. It was found that a snouted double annular combustor built with 256 ram-induction air scoops with a combustor open area giving a total pressure loss of 5.0 percent at a diffuser inlet Mach number of 0.25 gave the best overall performance of the configurations tested.
The relative merits of quasi-square wave inverter-motor technology versus a sine wave inverter-motor system were investigated. The empirical results of several tests on various sizes of wye-wound induction motors are presented with mathematical analysis to support the conclusions of the study. It was concluded that, within the limitations presented, the quasi-square wave inverter-motor system is superior to the more complex sine wave system for most induction motor applications in space.
A nuclear electric propulsion concept using a thermionic reactor inductively coupled to a magnetoplasma-dynamic (MPD) accelerator is described and the results of preliminary analyses are presented. In this system, the thermionic generating unit operates continuously at a power level of approximately 0.4 MW, while the MPD thruster operates intermittently at higher voltages and power levels. Energy storage is provided by building up a large current in an inductor. Periodically, the charging current is interrupted and the energy stored in the magnetic field of the inductor is utilized for a short duration thrust pulse. A typical thrust pulse is characterized by a power level of 1 to 4 MWe, a duration of 1 msec, and a duty cycle of approximately 20%. Results of the preliminary analysis show that approximately 85 to 90% of the power available from the thermionic converter array can be delivered to the MPD thruster for a nominal 400 kWe system with an inductive unit suitable for a flight vehicle. Optimized values of the total specific mass of the system including the thermionic reactor, the inductor, and the MPD thruster are estimated in the range of 23 to 24 kg/kWe.
Shock tube experiments measured hydrogen-air induction times near the second explosion limit. By matching these experimental results with numerically predicted induction times, the rate coefficient for the reaction H + O2 + M = HO2 + M was evaluated as k-sub 4,N2 = 3.3 (plus or minus .6) x 10 to the 15 cm to the 6th/sq mole/s.
Thermal profiles for the moon are calculated under the assumption that a pre-main-sequence T-Tauri-like solar wind excites both transverse magnetic and transverse electric induction while the moon is accreting. A substantial initial temperature rise occurs, possibly of sufficient magnitude to cause subsequent early extensive melting throughout the moon in conjunction with nominal long-lived radioactives. In these models, accretion is an unimportant direct source of thermal energy but is important because even small temperature rises from accretion cause significant changes in bulk electrical conductivity. Induction depends upon the radius of the moon, which we take to be accumulating while it is being heated electrically. The 'zero-age' profiles calculated in this paper are proposed as initial conditions for long-term thermal evolution of the moon.
Experiments in which a quasi-steady MPD thruster is driven by a large inductor demonstrate the feasibility of using inductive energy storage to couple an intermittent high power plasma thruster to a lower power steady state supply, such as a thermionic converter. Switching between inductor charging and MPD thrusting phases of the current cycle occurs smoothly, with the voltage spike generated during switching sufficient to initiate the arc discharge in the thruster without an auxiliary starting circuit. Further, the current waveforms delivered by the inductor are of a shape suitable for the quasi-steady thrusting process, and they agree with analytical estimates, indicating that the interaction between the thruster impedance and the inductive source is dynamically stable.
Possible heating mechanisms for an intense thermal cycle in the early solar system are considered, and inductive asteroid heating in a T Tauri environment is examined. Calculations of thermal models based on recent measurements of the electrical conductivity of carbonaceous meteorites are reported which are presumably more representative of actual conditions in the early solar nebula. Asteroidal thermal evolution is computed using a highly simplified code that restricts induction to the dc limit of the TM mode, approximates the complete unipolar-generation differential equation by a simple series-resistance model, and restricts the modeling of thermal conduction to a calculation of heat transfer across a thin planar shell of given thickness increasing with time, which blankets a body assumed to have an isothermal core. A grid of results is obtained for 20 combinations of asteroid radius and solar distance representing the populaton of asteroids. It is found that there is a relative heating maximum with respect to body radius, that this effect is due to the operation of two distinct heating-rate restrictions which have opposite radius dependences, and that the maximum current density is roughly proportional to the inverse of interior radius.
The high thrust density of the self-field magnetoplasmadynamic (MPD) thruster makes it a promising candidate for many advanced space missions. The high power requirements of this thruster lead to its operation in a pulsed mode from an energy storage device. The system characteristics of an inductive energy storage circuit with a solar array power from 25 kwe to 400 kwe are considered, by solving the circuit equations for the inductor charge and discharge phases. Using simple analytic models of the circuit components, the total system efficiency and inductance are determined as functions of the array output power and circuit resistance. The total system efficiency increases with array power and is acceptable only for low values of circuit resistance, indicating that superconducting circuitry may be desirable. The optimum charge-discharge cycle changes fundamentally as the circuit resistance is decreased through a critical value dependent on the thruster operating characteristics.
An induction powered implanted monitor for epidurally measuring intracranial pressure and telemetering the pressure information to a remote readout is disclosed. The monitor utilizes an inductance-capacitance (L-C) oscillator in which the C comprises a variable capacitance transducer, one electrode of which is a small stiff pressure responsive diaphragm. The oscillator is isolated from a transmitting tank circuit by a buffer circuit and all electric components in the implanted unit except an input and an output coil are shielded by a metal housing.
Electrical induction in Io's ionosphere, due to the corotating plasma bound to the Jovian magnetosphere, is one possible source for the attainment of the high temperatures suggested by the large scale height of Io's ionosphere. Unipolar induction models are constructed to calculate ionospheric joule heating numerically, whose heating rates lie between 10 to the -9th and 10 to the -8th W/cu m. The binding and coupling of the ionosphere is due to the dense, and possibly ionized, neutral SO2 atmosphere, and there appears to be no need to postulate the existence of an intrinsic Ionian magnetic field in order to retain the observed ionnosphere.
Thermal evolutionary models of the asteroids and the moon based on the hypothesis of electrical inductive heating by a dense primordial solar wind are compared with observation. Inferences (derived from spectroscopy) of asteroidal mineralogy when compared with electrical heating models, the variation of cooling rates recorded in iron meteorites, and the occurrence of the lunar magma ocean event lend support to the hypothesis of inductive heating. A high primordial solar rotation rate and magnetic field together with the loss due to plasma outflow of a substantial fraction of the initial solar mass would follow.
The moon constitutes a nonhydromagnetic, but electrically conducting, target for the solar wind whose response reaches a peak as frequency increases and diminishes with further increase in frequency, suggesting the presence of the magnetic quadrupole moment. Magnetometer measurements of induction using Explorer and Apollo instruments are studied from both the harmonic and transient standpoint, and the resulting determination of internal bulk electrical conductivity is discussed. The closeness of the estimated internal temperature to the Ringwood-Essene solidus at 150-250 km depths suggests a layer of enhanced conductivity in lieu of high temperature. A reduced core radius estimate with a one-sigma upper limit of 360 km is reported. The discussion of lunar electrodynamics presented is restricted to the problem of induction, with only passing reference to flow fields and regional electric fields.
This paper describes the development of a transistorized PWM inverter-induction motor traction drive system. A vehicle performance analysis was performed to establish the vehicle tractive effort-speed requirements. These requirements were then converted into a set of inverter and motor specifications. The inverter was a transistorized three-phase bridge using General Electric power Darlington transistors. The description of the design and development of this inverter is the principal object of this paper. The high-speed induction motor is a design which is optimized for use with an inverter power source. The primary feedback control is a torque angle control with voltage and torque outer loop controls. A current-controlled PWM technique is used to control the motor voltage. The drive has a constant torque output with PWM operation to base motor speed and a constant horsepower output with square wave operation to maximum speed. The drive system was dynamometer tested and the results are presented.
The assessment of the degree of hot corrosion attack on nickel based alloys is a difficult task, especially when the definition specifies that it must be in terms of metal consumed and even more difficult if the measurement must be nondestructive. The inductance of a solenoid coil responds to changes in volume of fill and composition of metal cores, therefore, it may be used for nondestructive measurement of hot corrosion. The hot corrosion of U700 was studied at 900 C in a Mach 0.3 flame doped with 0.85 wppm of sodium. The change of inductance was found to define the known corrosion behavior and to suggest its use as a tool with predictive capabilities. Sufficient sensitivity exists to detect oxidation of this alloy at 900 C.