Hollow ballistic pendulum for plasma momentum measurements

Abstract

A novel pendulum design—hollow ballistic pendulum—is suggested for plasma momentum measurements. It has an advantage over the pendula used earlier in laser plasma experiments of being insensitive to a momentum of matter evaporated and scattered by the pendulum wall exposed to the plasma, which usually exceeds plasma momentum to be measured. Simple expressions describing pendulum performance are derived, and requirements of shape and size are established. Using this kind of pendulum in experiments on laser acceleration of thin foils made it possible to measure the momentum of accelerated foil with an accuracy of about 10%.

The electrodeless Lorentz force (ELF) thruster experimental facility

“…Various pendulum designs have previously been used to determine plasma impulse. [27][28][29] This design specifically addresses the issues of electromagnetic interference and plasma-pendulum interactions.…”

Space Simulation Testing of the Helicon Double Layer Thruster Prototype

“…Since the laser displacement system is placed outside the vacuum chamber, the measurement approach used here is free from RF interference and thermal effects. This instrument could also be used to measure the thrust in the exhaust of other electric propulsion devices (Inutake et al, 2007;Blackhall and Khachan, 2007) and the m omentum flux of ion beams formed by expanding plas mas (Corr et al, 2007(Corr et al, , 2008 or fusion experiments (Goncharov et al, 1988).…”

“…A compact cantilever force probe based on the pull-in phenomenon in microelectromechanical-system electrostatic actuators has been recently em ployed for plasma pressure measurements in the ISTTOK tokamak (Nedzelskiy et al, 2007). Ballistic pendulum s have been employed for momentum measure ments of laser-produced plasmas, which are of interest to the fusion research community, for many years (Grun and Ripin, 1982;Goncharov et al, 1988). These pendulum s consist of a planar target, often made of Mylar or brass, suspended by nylon threads.…”

Canted Current Sheet Mass Leakage and its Impact on Pulsed Plasma Thruster Performance

“…Although a momentum plate is not as reliable as a thrust stand, in our case it was the most convenient way to measure impulse, as the accelerator was built for good optical access and a low inductance connection to the pulse forming network and cannot be mounted on a thrust stand. Momentum plates of various designs have been used by researchers in the past to measure the impulse of pulsed plasmas [10][11][12][13][14][15][16].…”