Edison effect

In 1913, Coolidge [COO 13] imagined another kind of X-ray source. The cathode is comprised of a tungsten filament heated by the Joule effect. According to the Edison effect, this filament emits electrons that are accelerated by an electrical field and bombard the anticathode which then emits X-rays. The entire device is placed in a sealed tube inside which the pressure must be as low as possible. A schematic view of such a tube is shown in Figure 2.3. 

J. J. Thomson found that the negative electrons produced in discharge tubes are the same with various residual gases and different kinds of electrodes it was known that they are also emitted by heated metals (the Edison effect), by the action of ultraviolet light or X-rays on metals, and in some chemical reactions hence Thomson concluded that they are a common constituent of all atoms. 

The earliest electronic computers were developed at the time of World War 11 and involved numerous vacuum tubes. Since vacuum tubes are based on thermionic emission, the Edison effect mentioned above, they produced immense amounts of heat and involved the possibility that the heating element in one of the tubes might well burn out during the computation. In fact, it was standard procedure to run a program, one that required proper function of all the vacuum tubes, both before and after the program of interest. If the results of the first and last computations did not vary, one could assume that no tubes had burned out in the mean time. 

Celluloid, an artificial plastic made from nitrocellulose and camphor, was invented by Parkes from Britain and the Hiatt brothers, printers in the U.S.A. (USP 88634 (1869)). The inventions of photographic films by Eastman Co. in 1885 and of movies by Edison in 1895 markedly expanded the demands for celluloid, bringing about a major increase in large scale accidents, the effects of which were magnified by involving many people in enclosed spaces. 

Thermionic effect The electrons within the electron fluid have a distribution of velocities very much like that of molecules in a gas. When a metal is heated sufficiently, a fraction of these electrons will acquire sufficient kinetic energy to escape the metal altogether some of the electrons are essentially boiled out of the metal. This thermionic effect, which was first observed by Thomas Edison, was utilized in vacuum tubes which served as the basis of electronics from its beginning around 1910 until semiconductors became dominant in the 1960 s. 

Edison, G.R. 1978. The drug laws Ae they effective and safe Journal of the American Medical Association 239(24) 2578-2583. 

Mewhinney J, Edison A, Wong V. 1987b. Effect of wet and dry cycles on dissolution of relatively insoluble particles containing Pu. Health Phys 53 377-384. 

---