Test bench operation of a plasma fuelling device at IPR

Abstract

A single barrel pellet injection system has been developed at Institute for plasma research (IPR). It is an in-situ pipe gun type injector, in which, a solid hydrogen pellet formed at freezing zone is accelerated to high speed by using high pressure propellant gas. The pellet injection system is equipped with a GM-cycle cryogenic refrigerator for pellet formation, a fast opening valve for pellet acceleration and diagnostic system to measure the ejected pellet parameter. A pellet is formed in-situ in the gun barrel connected to cryogenic refrigerator maintained at a temperature < 10 K. With proper thermal heat load minimization on cryo region, solid hydrogen pellets are obtained. In test bench operation various sized cylindrical pellets of dimension (length x diameter) 1.6 mm × 1.8 mm and 4 mm × 4.25 mm are produced. The ejected pellet speed is varied over a range from 700 to 1000 m/s by regulating propellant pressure. Whereas, the speed of a pellet is measured by time of flight based light gate diagnostic system, pellet quality and its size are estimated from fast camera imaging system. The reliability of pellet formation and injection in present experimental system is greater than 95%.