IN-BORE INSTRUMENTATION DIAGNOSTICS FOR LARGE-BORE EMLS

A "flying laboratory" technique of in-bore diagnostics for large-bore electromagnetic launchers (EMLs) is being developed under the direction of Michael J. Fernandez. The high pressure, heat, and magnetic flux environment of the EML and its containment structures do not allow easy implementation of conventional diagnostic techniques. Researchers have relied on remote sensing methods, such as B-dot probes (isolated from the bore), for data. The accuracy and relevance of such discrete, remote measurement is somewhat questionable. An inhouse program has been initiated to determine the feasibility of making measurement of EML parameters on board a projectile. This technique utilizes off-the-shelf components in a configuration that has been proven effective in measuring projectile acceleration in the bore of propellant driven guns. The goals of the In-Bore Instrumentation/Diagnostics (IBID) testing program are to demonstrate the feasibility of instrumenting EML projectiles with a high shock accelerometer (200 kgee), a high shock recorder (100 kgee) and batteries, to power the on board memory, while obtaining direct, continuous and reliable acceleration profiles. From these, accurate projectile velocity may be obtained by integration for any position in the barrel. Another goal is to demonstrate instrumentation and recorded data survivability at as high an acceleration and velocity as possible. Having established feasibility, the technique could easily be extended to other EML parameters. Accurate knowledge of projectile acceleration is particularly essential in future armature studies.