Radar Coolant
Coolanol (silicate ester) was used in several military radars in the 1970s. However, it is hygroscopic, leading to formation of highly flammable alcohol. The loss of a U.S. Navy aircraft in 1978 was attributed to a silicate ester fire. Coolanol is also expensive and toxic. The U.S. Navy has instituted a program named Pollution Prevention (P2) to reduce or eliminate the volume and toxicity of waste, air emissions, and effluent discharges. Because of this Coolanol is used less often today.
Coherent microwave amplifiers operating above 1,000 watts microwave output require liquid coolant, like traveling wave tube and klystron. The electron beam must contain 5 to 10 times more power than the microwave output, which can produce enough heat to corrupt the vacuum with plasma. This flows from the collector toward the cathode. Magnetic focusing for the electron beam forces ionized gas atoms into the same location as the electron beam. Plasma ions flow in the opposite direction of the electron beam. This introduces FM modulation, and that degrades Doppler performance. Liquid coolant with minimum pressure and flow rate is required to control collector gassing, and deionized water is normally used with most high power surface radar systems that utilize Doppler processing.
Read more about this topic: Radar, Engineering
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