Malter effect

Abstract: The thin film field emission (Malter effect) from ${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$ films on Al was investigated (1) by coating the film with a fine dust of willemite and observing the behavior of the primary beam; (2) by forming an electron image of the surface by means of the Malter current from it. The behavior of these films, while exhibiting the Malter effect, may be summarized as follows: 1. The potential of the front surface of the electrode is a saw-tooth function of time at any point, and nonuniform over the surface at any instant. 2. The current density of the primary beam at the surface varies, correspondingly, because of the varying electric field above the surface. 3. A time lag exists between the application of voltage across the film and the establishment of the Malter current. 4. The Malter current issues chiefly from a number of isolated points on the surface, and the current from any one of these points varies with time. 5. The emitting points are scattered over the entire surface of the electrode, with some preferential grouping in the region covered by the primary beam. 6. Some of the electrons constituting the Malter current have a kinetic energy corresponding in order of magnitude to the voltage drop across the film. 7. The Malter electrons leave the film with a wide range of speeds.

Abstract: Using a preionization scheme based on the Malter effect, small‐signal gains ≳5%/cm at 10.6 μm ahve been produced in a 1‐mm2‐cross‐section waveguide CO2 amplifier at total operating pressures of 100–760 Torr. Comparisons are made between this preionization scheme and those using electron beams.

Abstract: Preionization is achieved in transverse-discharge gaseous lasers by means of the Malter effect. In two embodiments, the preionization is achieved either with a metal electrode which is the cathode during preionization and then is the anode during the subsequent pumping phase, or by means of a separate set of preionization electrodes. These preionization cathodes are metal electrodes, such as aluminum or tantalum electrodes, exhibiting high secondary electron emission by the Malter effect. High-field electron emission from these preionization cathodes is inherently possible because of a thin insulating layer on the surface. This layer separates positive ions attracted to the surface from the conducting metal and thereby creates a very high field gradient over a very short distance. In a preferred embodiment, uniform initial ionization is created during the preionization phase of operation; and the excitation is supplied by an electric field which is lower than that required to sustain the discharge; and the active medium is enclosed in an optical waveguide free of interfering structure.