The Physics of Energy provides a comprehensive and systematic introduction to the scientific principles governing energy sources, uses, and systems. This definitive textbook traces the flow of energy from sources such as solar power, nuclear power, wind power, water power, and fossil fuels through its transformation in devices such as heat engines and electrical generators, to its uses including transportation, heating, cooling, and other applications. The flow of energy through the Earth's atmosphere and oceans, and systems issues including storage, electric grids, and efficiency and conservation are presented in a scientific context along with topics such as radiation from nuclear power and climate change from the use of fossil fuels. Students, scientists, engineers, energy industry professionals, and concerned citizens with some mathematical and scientific background who wish to understand energy systems and issues quantitatively will find this textbook of great interest.
Tobacco hornworms (Manduca sexta) were exposed during their larval life to 4 mW/cm2 (SAR = 23 W/Kg) circularly polarized pulsed microwaves (2695 MHz, 2 μS, 500 pps) for 12 hours a day in an environmentally controlled anechoic chamber. Following the irradiation period, various insect development parameters were monitored until the next generation was produced. Microwaves did not have any influence on food consumption of the larvae, but larval weight, mortality and the rate of development during the successive larval stages were affected. There was no occurrence of deformities. No effect could be detected on pupal development, sex ratio and mortality. Adult insect fertility and fecundity were not affected by electromagnetic energy deposition.
There have been reports that electromagnetic radiation (EMR) alters the function of the immune system; however, these reports are often contradictory. This review reexamines the literature and attempts to evaluate the data on potential mechanisms of interaction of EMR on mammalian immune function. This report concludes that there is no convincing evidence that EMR effects on the human immune system are a health hazard. It was suggested by some authors that long-term EMR exposure may impair immune surveillance, and hypothetically thus facilitate tumor growth. Additional research is needed to prove or disprove this hypothesis. Available data indicate that EMR exposure does not affect the ability of cells of the immune system to respond to a subsequent challenge. However, the time-course and magnitude of the response may be affected by exposure following stimulation. Research to date provided evidence that at least at some frequencies and/or amplitude and pulse modulations, the site of primary interaction of EMR is at the cell membrane. However, it was shown that one specific response, the increase in B complement-receptor positive lymphocytes (Cr+) in the mouse is under genetic control by a single gene localized on chromosome 5.It is suggested that cells of the immune system are a convenient model for further studies on mechanisms of EMR interaction with living systems. Future research should be directed at exploring beneficial medical applications of EMR modulation of immune responses.
Single sided microwave applicators based on waveguide and stripline configurations were developed specifically for the purpose of sealing cartons by reheating previously applied “hotmelt”. Sealing times of less than half a second have been achieved.Slotted waveguide applicator positioned on beer carton to simultaneously heat four spots across the width.
The behaviour of a material in a microwave field is di-rectly related to the temperature dependence of the imaginary part of the permittivity of a material. According to the conditions of thermal evacuation chosen, for example convection, its heating is either stable or unstable. For some materials, a critical temperature can be defined which represents an upper limit beyond which the heating is unstable whatever the convective heat transfers. The optimal conditions which can be obtained through the use of an automatic regulation of the heating are, as a consequence, determined. The microwave heating of EPDM rubber is treated as an example.
The history of power transmission by radio waves is reviewed from Heinrich Hertz to the present time with emphasis upon the free-space microwave power transmission era beginning in 1958. The history of the tech-nology is developed in terms of its relationship to the intended applications. These include microwave powered aircraft and the Solar Power Satellite concept.
AbstractFor fusion plasma heating, two types of 2 GHz 1 MW klystrons were developed. They were 6-cavity, frequency-tunable klystrons which could deliver 1 MW continuous output power for 10 s duration. Each klystron has a similar electron gun with a modulation anode, and an evaporation-cooled collector.A prototype klystron was tested for 1 MW performance successfully and a two-window version was also manufactured in order to reduce the thermal stress of the window material. A high-power magic tee was used in order to combine the two power outputs and to produce more than the 1 MW power output. The window temperature was observed to rise, with light emission. The measured temperature rise was about 16°C at the end of 10 s duration, when the klystron was operated at the power level of 500 kW per window.An external digital computer was used to control the high-speed tuning mechanism several times during every one pulse operation.
Pecan kernels were subjected to steam heating and dielectric heating treatments at 43 MHz and evaluated initially and during storage for 16 weeks at 21°C and 65% relative humidity to determine the effects of the treatments on their quality.Both types of heating treatments had a stabilizing influence on pecan flavor as determined by a sensory evaluation panel and by analytical determinations of peroxide values. Further, dielectric heating did not produce the darkening of kernel color that results from steam heating.Further studies are needed before the methods can be assessed for practical use.
Microwave drying of Spinacia oleracea leaves was experimentally compared to electric heating and room temperature drying. Differences in water loss kinetics have been analyzed and a theoretical model has been proposed. In drastically dried leaves strong alterations of the internal morphological structure are present while surface characteristics appear satisfactorily conserved. Chlorophyll content in acetone extracts of microwave dried leaves does not appear as reduced as in conventional methods.
The Journal asked John Gerling of Gerling Laboratories, Modesto, California to search for the US. Patents on the solid state microwave oven. We also asked other people for their input and comments.The following section is what we have found so far; readers are invited to send in other relevant material on the subject and the Journal is particularly interested in patents from other countries in this area.In no way is the Journal suggesting solid state microwave ovens are realistic or about to come on the market. In our opinion it will be several years and then in very specialized applications. As but one. example of the economics of the magnetron versus the solid state oscillator, we have been told that one manufacturer in Asia is selling 500 W magnetrons for use in low power microwave ovens with a ten year original-purchaser warranty for US$8.65 - in quantities of 11,000. Even so, it would be very surprising if microwave ovens with solid state power sources were not for sale in this century.
This study compared microwave-convection, forced-air convection and conventional electric ovens as to time and energy requirements, uniformity of cooking, and effect on cooking losses, sensory characteristics, moisture, fat, thiamin and riboflavin content of top round beef steaks. Sensory evaluation indicated no significant difference in juiciness; tenderness, including number of chews; intensity of beef flavor; and external color of the steaks cooked by the three ovens. Also, moisture, fat, thiamin and riboflavin content of the meat did not differ among treatments. Total cooking losses and percentage evaporation were greater (P<0.05) for steaks cooked in the microwave-convection oven than for those cooked by the other two methods. Drip losses were greater (P<0.05) with the microwave-convection than with the forced-air convection method of cooking top round beef steaks. The least total cooking time was required for the microwave-convection oven and the most for the forced-air convection oven. On a watt-hour basis, the microwave-convection oven required less total energy than the other two ovens, although the watt-hours required for preheating was the same for all methods.
Network Analysers provide a powerful diagnostic tool involving swept frequency techniques for the design of radio frequency applicators. Such prototype applicators have been used with a number of industrial materials to assess the feasibility of drying or heating with radio frequency power. Essentially, two aspects are considered in this paper. Firstly, with the prototype applicators not coupled to an oscillatory (tank) circuit of a radio frequency source, the resonance characteristics and Q-factors are measured leading to the establishment of the utilisation efficiency. Secondly, the interaction at lower power between the loaded applicator and the tank oscillatory circuit which is coupled to it, is considered in terms of the return loss and the impedance loci. A critical electrode separation, dc, is observed which is dependent on the material loading and at which the impedance loci and return losses of the loaded applicator and tank oscillatory circuits are identical. Such an observation may be a necessary, albeit not sufficient, condition for optimum matching.
Two microwave procedures were compared with traditional stir-fry cooking for pork tenderloin. The microwave/heat resistant glass-plate method achieved a 26% energy saving, and the stir-fry method provided a 51% energy saving as compared to the microwave/browning utensil procedure. The meat cooked by the three methods did not differ in the sensory attributes of flavor, juiciness, color intensity or color uniformity. The meat cooked by the two microwave methods was less intense in aroma and less tender than the stir-fried pork, but the magnitude of difference between the means was small. Moisture, fat content, thiamin and riboflavin retention of the meat were not significantly different among the three cooking methods.
The need of the fusion energy program for high power mm-wave sources for use in plasma heating experiments has resulted in the rapid development of gyrotron oscillators.
Key requirements for microwave power tubes for fusion heating are high efficiency, long life and stability in the presence of load mismatches. Operating frequencies presently range from UHF to 60 GHz, while future machines will operate at frequencies of 2 to 200 GHz with installed heating capacities of tens of megawatts. These requirements can be met with klystrons for frequencies from 1 to 20 GHz and with gyrotrons for 20 to 200 GHz.This paper presents details of existing klystrons and gyrotrons in plasma heating service. Design and performance information is presented for the VKS-8269A and VKC-7849 klystrons which provide 500 kW at 2.45 GHz and 250 kW at 4.6 GHz, respectively. Similar information is provided for the VGA-8050A and VGE-8060A gyrotrons which provide 200 kW at 28 and 60 GHz.The capabilities of klystrons and gyrotrons as a source of microwave power are reviewed. The design considerations controlling power capability and efficiency are described along with comments on reliability with information on field experience. It is shown that klystrons and gyrotrons are the appropriate devices for generating the large amounts of microwave power needed for heating in plasma fusion devices.
The U.S. Government’s support of the fusion program is predicated upon the long-term need for the fusion option in our energy future, as well as the near-term benefits associated with developments on the frontier of science and high technology. As a long-term energy option, magnetic fusion energy has the potential to provide an inexpensive, vast, and secure fuel reserve, to be environmentally clean and safe. It has many potential uses, which include production of central station electricity, fuel for fission reactors, synthetic fuels, and process heat for such applications as desalination of sea water. This paper presents an overview of the U.S. Government program for magnetic fusion energy. The goal and objectives of the U.S. program are reviewed followed by a summary of plasma experiments presently under way and the application of wave heating to these experiments.
The general physics of plasma wave heating of magnetically confined plasma will be discussed. A presentation of the basic physical mechanism, theoretical models, and experimental results will be given. Emphasis will be placed on heating in the ion cyclotron range of frequencies, the use of lower-hybrid waves to generate current, and the use of electro-cyclotron heating in tandem mirrors. Additional applications will also be given.
