Electrothermally augmentation of a solid propellant launcher

Abstract

The augmentation of a ballistic process, based on the well known solid propellant burning by an electrothermal (ET) energy source, is the subject of an experimental and theoretical investigation to obtain improved launching techniques. The plasma jet formation method, the internal ballistics modeling approach and the experimental test bed are described. Experimental results are disclosed showing the enhanced burning rate of a solid propellant ignited and augmented by the injection of plasma jets. We also present preliminary experimental evidence of improved performance of the new proposed method over that of conventional ballistics using solid propellant alone.

Electrothermal tapered capillary hyper jet focused-injection plasma source concept

“…T exit peak (eV ) = 2.752 e − 0.02 θ , R 2 = 0.99507 (8) Plasma parameters have strong axial gradient and less or negligible radial gradient. An example of the axial and radial distribution of the plasma temperature for the 12.6mm to 6.6mm taper (θ= 33.69 o ) is investigated herein.…”

“…Electrothermal capillary plasma sources in the ETC guns were utilized as an igniter to the bulk-loaded propellant and as an augmentation mechanism to the burn rates of solid propellant [8]- [11]. The importance of ETC research is in its ability to launch projectiles at very high velocities in excess of 5-7km/s, which can't be achieved by conventional gun systems.…”

“…Elecrothermal capillary discharges used in most ETC experiments were cylindrical with an average length of 9-15cm and average diameter 4-10mm, and either operating in the ablation-controlled confined arc regime or fused with a thin aluminum wire as an exploding fuse to initiate the discharge [2], [3], [5], [8]- [11]. Pulse length varies between 0.1-1.0ms with discharge currents in the range of few kA to 100s kA, and can provide plasma pressure of several 100MPa, exit plasma velocities of up to 5km/s and greater, and plasma temperature in the range of 10,000-40,000 o K [3][4][5][6][7][8][9][10][11][12][13]. Modeling of these capillaries was either in 0-D or 1-D based on the assumption that the plasma temperature distribution is constant along the radius of the capillary [4]- [15].…”

Investigation on the flow field characteristics of a highly underexpanded pulsed plasma jet

“…Electrothermal plasmas are also of interest for applications such as rocket propulsion, electrothermal-chemical launchers, and hypersonic mass acceleration technology (Hewkin and Figura, 1993;Greig et al, 1993). Electrothermal-chemical (ETC) gun propulsion uses a pulsed power system to generate a plasma, which is then injected into a chemical propellant to improve gun performance, control, and safety of gun systems (Schmidt et al, 1975;Kaplan et al, 1993;Gilligan et al, 1991). In an ETC gun, an electrical energy pulse is first converted to the thermal and kinetic energy of a plasma, and the plasma energy is used to ignite the chemical propulsion charge (e.g., solid propellant) as well as to enhance gun performance by taking advantage of a number of unique plasma characteristics.…”

Non-US electrodynamic launchers research and development

“…While this effort is performed by the staff of the Soreq Nuclear Research Center, it receives significant funding from the United States,'3 and some of the more recent gun firings have been performed in the United States at the Eglin Air Force Base, Florida. Research at Soreq began several years ago with small caliber firings but progressed rapidly to firings at 60-mm bore diameter (Juhasz et al, 1992;Kaplan et al, 1993), and is now well into a firing program using a modified 105 mm cannon. January 1995).…”