1. Field of Invention
The present invention relates to atmospheric testing instruments and in particular to ion spectrometers.
2. Discussion of the Prior Art
It is well known that the interaction of air molecules with energy radiation produces various, charged, ionic species. Ultraviolet radiation from the sun and radioactive radiation from the bombs and reactors are examples of such ion-producing, energy radiation.
It is clearly desirable to be able to take accurate, ion-density measurements to facilitate, for example, an investigation of the interaction of solar energy with the atmosphere, or to facilitate the measurement of nuclear bomb radiation or nuclear reactor leakage.
Various devices and methods have been adopted in the prior art to measure this basic, physical, atmospheric parameter (ion density). These devices and methods are generally based around a device called a "Gerdien Condenser." The operation of the "Gerdien Condenser" is in turn based on the fact that each ion has a different mobility factor K which is dependent on the chemical nature of the ion, and the fact that the drift velocity V of each ion is related to this mobility by the equation V = KE where E is the electric field. In a time-independent, electric field the distance traveled by an ion in a time t depends only upon its mobility K. Thus, this ion-mobility individuality may be used to effect a separation of the various charged ions present.
A "Gerdien Condenser" consists of a small-radius, cylindrical electrode and a large-radius, cylindrical electrode concentrically located with respect to each other and with a potential difference between them. The atmosphere or gas to be tested is passed through an annular ring located in the nose of the spectrometer, which covers the opening between the two, concentric cylinders. The center electrode is designated as the collector electrode and the system is set up accordingly. Thus the annular ring in the nose is placed relatively close to the outer, cylindrical electrode and the electrical potential on the center electrode is made opposite in polarity to the charge of the ion that it is desired to measure. Thus, upon the entrance of the ions through the annular ring, an ion trajectory is set up from the larger annular ring to the small-radius cylindrical electrode. The ions intersect with the center electrode at different points depending upon their velocity which, in turn, is dependent on the individual mobilities.
A major problem with this design is that when this instrument is carried by such upper atmosphere vehicles as rockets, airplanes, and balloons, a very high air or gas turbulence is generated within the chamber between the concentric cylinders. This air turbulence has a substantial effect on the ion-measurement accuracy.