Radar phosphors

To preserve the reflection signal, a long decay phosphor is required. The phosphors used in the past were generally composed of two phosphors, one with a long decay. Thus, the screen exhibits two colors, that of the target and the other forming the background which is refreshed in every 360 ° rotation of the radar antenna. Radar phosphors include ... 

The Calcium Halophosphate Phosphors. Early fluorescent lamps used various combinations of naturally occurring fluorescent minerals. The development of the calcium halophosphate phosphor, Ca (P0 2(Cl, F) Sb ", Mn, in the 1940s was a significant breakthrough in fluorescent lighting (7). As is often the case in new phosphor discoveries, this phosphor was found accidentally while searching for phosphors for radar screens. 

The main categories of electrical/optical ceramics are as follows phosphors for TV, radar and oscilloscope screens voltage-dependent and thermally sensitive resistors dielectrics, including ferroelectrics piezoelectric materials, again including ferroelectrics pyroelectric ceramics electro-optic ceramics and magnetic ceramics. 

P-2 ZnS Cu ZnS, CuS, MgCl2, NaCl Green-emitting (520 nm) phosphor long decay for radar... 

P-12 (ZnMg)F2 Mn2+ ZnF2-4H20, MgF2, MnF2 Radar tubes where moderate decay was desirable. Orange-emitting phosphor (588 nm)... 

Long decay time phosphor for use in radar. Orange emission at 575 nm... 

Copper-activated zinc and cadmium sulphides exhibit a rather long afterglow when their irradiation has ceased, which is favourable for application in radar screens and self-luminous phosphors. 

These orange-emitting phosphors have a long afterglow time and are therefore still used in special radar tubes and oscilloscopes [5.296], [5.307], [5.418], despite their low stability towards burn-in compared with other cathode-ray phosphors. 

Phosphors for cathode-ray tubes, television screens, monitor screens, radar screens, and oscilloscopes are tested under electron excitation. Electron energy and density should be similar to the conditions of the tube in which the screen will be used. The phosphors are sedimented or brushed onto light-permeable screens and coated with an evaporated aluminum coating to dissipate charge. The luminescence brightness and color of the emitted light are measured with optical instruments such as photomultipliers or spectrophotometers. 

From this discussion, it should be obvious that the two most important properties of cathode-ray phosphors are the response to electron-beaun excitation (brightness) and the decay time. We require a long-decay phosphor for radar applications and a short-decay phosphor for television usage. Nearly all the cathode-ray phosphors are based on the zinc and cadmium sulfides because they exhibit the highest efficiency to cathode-ray excitation. ZnS forms a series of solid solutions with CdS whose emission band can be shifted from the blue (ZnS Ag) to the red phosphor. 

There are many other types of cathode-ray tubes which find application oscilloscope tubes, tubes with very short decay times, radar tubes, tubes with high-resolution screens, and so on. For these tubes and the phosphors they require, we refer to a recent review paper [1]. 

Molycorp, a wholly owned subsidiary of Unocal Corp., was the only company to mine rare earth minerals in the United States in 2002. The rare-earth separation plant operations stopped in 2003. Molycorp mined bastnasite, a rare earth fluorocarbonate mineral, as a primary product at Mountain Pass, California. The value of domestic ore production was estimated at 31 million in 2002 the estimated value of refined rare earth minerals was more than 1 billion. The end uses for rare earth products in 2000 were as follows automotive catalytic, 22 percent glass polishing and ceramics, 39 percent permanent magnets, 16 percent petroleum refining catalysts, 12 percent metallurgical additives and alloys, 9 percent rare earth phosphors for lighting, televisions, computer monitors, radar, and x-ray intensifying film, 1 percent, and miscellaneous,... 

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