Watts Of Power Research Articles

Low Powered Induction Heater for Laboratory Use

Certain laboratory processes require low-powered radiofrequency heating with fine, continuous control. A lightweight low-powered induction heater which is capable of delivering about 20 watts of power into a load 12 feet from the heater with fair efficiency was developed to meet this need.

THERAPEUTIC POSSIBILITIES OF MICROWAVES

In spite of the fact that radar is considered as one of the outstanding developments of World War II, its principles are not new. Radar operates on the principle of sending out extremely short pulses of high frequency energy and measuring the time interval required for this burst of energy to reach its destination and be reflected back to its source. By knowing the length of time required for the energy to travel back and forth, distance to the object can be accurately measured. The magnetron is essentially a device which can be pulsed rapidly for intervals of the order of microseconds and is capable of delivering hundreds, thousands or millions of watts of power at wavelengths in the centimeter range or shorter. During the war the magnetron and other microwave tubes have been used almost solely for detection and direction applications. For these applications a pulse-echo system is employed.

Wilson cloud machines for portable use

Two new forms of Wilson cloud apparatus, developed for stratosphere balloon flights and suitable for portable use, are described. The machines are of light weight, require only small amounts of electric power, and are arranged for optional control by Geiger‐Muller counters. Both machines employ baffles for removing turbulence from the cloud chamber; one uses a metal bellows, but no diaphragm; the other uses a thin rubber diaphragm and a bellows pump. Vacuum tube circuits control the timing of events connected with the expansion cycle. Stereophotographs are taken with flash bulbs, or with a spark illuminator that uses only 10 watts of power from an a.c. supply.

Wilson Cloud Machines for Portable Use

Two new forms of Wilson cloud apparatus, developed for stratosphere balloon flights and suitable for portable use, are described. The machines are of light weight, require only small amounts of electric power, and are arranged for optional control by Geiger‐Müller counters. Both machines employ baffles for removing turbulence from the cloud chamber; one uses a metal bellows, but no diaphragm; the other uses a thin rubber diaphragm and a bellows pump. Vacuum tube circuits control the timing of events connected with the expansion cycle. Stereophotographs are taken with flash bulbs, or with a spark illuminator that uses only 10 watts of power from an a.c. supply.

Effect of Exposure of Chickens Inoculated with Rous Sarcoma to Electromagnetic Waves of High Frequency

The experiments to be described in this paper were undertaken to determine the effect of waves emitted by a high-frequency oscillator on the rate of tumor growth, and the extent of the metastases, in chickens inoculated with living cells of the Rous sarcoma. The waves were generated by a short-wave radio transmitter, the energy being concentrated between two large condenser plates.1 The most readily demonstrated effect of exposure of animals to these waves is on the body temperature, which may be markedly raised and maintained at a high level for considerable periods of time, depending on the duration of exposure. When the animal is removed from the machine the temperature soon subsides to normal. A number of reports indicate that all effects of exposure to these waves are due to this increase in temperature, rather than to any specific action of the waves themselves, Christie and Loomis exposed mice to ultra-high-frequency waves under constant atmospheric conditions. They concluded that the effects produced could be fully explained on the basis of the heat generated within the animal by this procedure. Kahler, Chalkley and Voegtlin exposed cultures of Paramecia to four meter waves and found that the changes in form, motility, rate of multiplication, and the lethal temperature were the same as those observed when similar cultures were heated in a water bath. Knudson and Schaible made a very complete examination of the blood of dogs exposed to an oscillator delivering 150 watts of power at high frequencies of from 9,000 to 12,000 kilocycles. All the chemical and physical changes in the blood can be fully explained, according to these authors, by the rise in temperature of the animals, with resulting dehydration, oliguria and increased metabolism. Bischoff, Long and Hill made a study of the effect of hyperpyrexia produced by various means on the acid-base equilibrium of human blood. The one respect in which the hyperthermia produced by a short-wave radio transmitter differed from that produced by diathermy, warmed air, or hot water baths, was that it caused a fall in blood volume. Johnston in this laboratory has shown that the heating of cultures of B. pyocyaneus, B. prodigiosus and S. muriotitis for prolonged periods, by exposure to short-wave radiations, did not alter the type of colony, the pigment production, or the biological reactions of the species concerned. Nor did the radiations alter the antigenic factors of S. muriotitis. The lethal temperature for these organisms after exposure to the rays was found to be the same as when they were exposed to ordinary methods of heating.

Practical Aspects of X-ray Measurement, with Special Reference to a Standard Unit of Dosage

IN studying the problem of X-ray dosage we must consider both the quality of the ray transmitted by the filter, and the quantity transmitted per unit of time. Both the quality and quantity of this transmitted ray should be expressed in fundamental terms, if possible. Quality at present is expressed in terms of penetration or wave length, the latter a property of the ray itself, an objective standard. Quantity, on the other hand, is generally expressed biologically in terms of erythema, a phenomenon which involves two variable factors, namely, the patient's reaction and the roentgenologist's interpretation of that reaction. We should seek a unit of quantity which is fundamental, determined by a property of the rays themselves, and measurable to an exact degree; to bring into accord the various ideas of roentgenologists as to the quality or quantity, or both, to be used in X-ray therapy. Such a unit has already been presented and will hereinafter be described. Physics was not a science until physicists agreed on certain definite units of length, mass, and time; chemistry was not a science until chemists began to talk in terms of atomic and molecular weights, grams, cubic centimeters, and other definite units; units which mean the same thing to all chemists and to all physicists. The physician in writing out a prescription states so many minims, drams, grams, or ounces of a drug, or so many c.c. of a solution of a definite concentration. Not that any two physicians will necessarily prescribe the same amounts or the same drugs, but the drug and the amount are both in definite terms which allow of only one interpretation. What, then, is the condition in the X-ray field? One roentgenologist states that he uses so many milliampere minutes, at so many kilovolts, using a certain filter, and skin target distance to obtain a so-called erythema dose. But like numbers of milliampere minutes do not mean the same amount of X-ray energy with different machines, no two men agreeing on what constitutes an erythema dose. In general, equal amounts of filtered radiation will not produce a similar erythematous reaction on different patients, so that to define the amount of X-rays used, entirely by its biological effect, is very unsatisfactory. When you order an electric light bulb you are not primarily interested in the number of watts of power consumed in that bulb, but in the candle power coming from it. The old carbon filament and the newer Mazda may consume the same number of watts, but there is no doubt about which one gives the most light. Similarly, in X-rays we should not rate our tubes and apparatus by input, but by output and in terms of an X-ray candle power. As in the visible light, we cannot say that a red light is three times as strong as a blue one, but can only speak of relative intensities for two lights of the same color, so in X-rays we must first state the quality of the ray and then we can compare quantities.