1. Electric arc heaters have been used for aeronauticaltestpurposessincethelate 1950's,withthe adventoflong-range ballistic missiles andtheassociated needfortesting thermal protective materials for reentrybodies.The hightemperaturesandpressures required for this type of materials testing, as wellasothertestrequirements relating tostructures and propulsion, are not attainable by conventional means. Electric arc heaters are the only proven method of heating air to high temperatures (5,000 - 15,000 R)foraduration of several minutes.This is evident fromthecomparisonofvarioustypesoftest
2. 10,000 co I g> 5,000 available inthe H1 and HRfacilities produce a continually expanding flow field and, thus, a continuously varying impact pressure with axial distance from the nozzle exit. Through continuing upgrades, operation of the H1 heater at a chamber pressure up to 150atm has beendemonstrated, and various arc heater diagnostic experiments have been performed. Results from several of the arc heater diagnostic experiments are presented in Ref. 3. The new 65-MW H3 segmented arc heater was first operated in February 1995,andthe initialoperating results were presented in Refs. 4 and 5. An
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