Theta gun, a multistage, coaxial, magnetic induction projectile accelerator
Abstract
We experimentally and theoretically studied a multistage coaxial magnetic induction projectile accelerator. We call this system a theta gun to differentiate it from other coaxial accelerator concepts such as the mass driver. We conclude that this system can theoretically attain railgun performance only for large caliber or very high injection velocity and, even then, only for long coil geometry. Our experiments with a three-stage, capacitor bank-driven accelerator are described. The experiments are modeled with a 1-1/2 dimensional equivalent circuit-hydrodynamics code which is also described. We derive an expression for the conditions of coaxial accelerator-railgun velocity breakeven in the absence of ohmic and hydrodynamic effects. This, in conjunction with an expression for the magnetic coupling coefficient, defines a set of geometric relations which the coaxial system must simultaneously satisfy. Conclusions concerning both the existence and configuration of a breakeven coaxial system follow from this requirement. The relative advantages and disadvantages of the coaxial induction projectile accelerator, previously cited in the literature, are critiqued from the viewpoint of our analysis and experimental results. We find that the advantages vis-a-vis the railgun have been overstated.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- November 1985
- Bibcode:
- 1985STIN...8628269B
- Keywords:
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- Hydrodynamics;
- Magnetic Induction;
- Projectiles;
- Railgun Accelerators;
- Computer Programs;
- Design Analysis;
- Mathematical Models;
- Engineering (General)