Ram Accelerator Facilities From Around the World

Ram accelerator research facilities have been constructed in USA, France-Germany, Japan, China and Brazil.  Significant theoretical modeling efforts have also been carried out in these and other institutes that do not have facilities.  Brief descriptions, a few figures, and some pertinent results from these other ram accelerator research efforts are presented here.

The largest ram accelerator to date was constructed at the Army Research Laboratory in Aberdeen, MD, USA, under the direction of David Kruczynski.  The ram accelerator test section was a 120-mm-bore and fabricated from surplus 120-mm cannon barrels.  A conventional 120-mm cannon was used as a pre-launcher.  Each cannon barrel was ~5-m-long, and 4 were ultimately used for a total test section length of 20 m.  This device was unique in that it fired projectiles out into Chesapeake Bay, some of which could be recovered during neap low tide.  Multi-stage experiments were successful in accelerating 5 kg projectiles from 1.2 to 2.0 km/s.  High-speed photos of the projectile in a 2-m-long transparent tube showed the projectile accelerating even as the tube was exploding behind it.  Experiments were also carried out in a 5-m-long high pressure section (rated for 3000 psi fill pressure). 

Three different ram accelerators were constructed at the French-German Research Institute of Saint-Louis (ISL), France.  The 90-mm-bore facility was totally enclosed in a blast tank for its full length (directed by Marc Giraud).  The powder-gun propellant gas required extensive venting in a highly perforated tube prior to ram accelerator.  The final catcher blocks were “crushed BMWs”.  Velocities up to 2.4 km/s were achieved here in multi-stage experiments.  Flash x-ray images of the projectiles showed that material erosion was a key issue when using aluminum alloy projectiles. 

Under the direction of Dr. Gunter Smeets and Prof. Frederich Seiler, a 30-mm-bore test section was fabricated with 4 internal rails for projectile stabilization.  Axisymmetric experiments in the superdetonative velocity regime were carried out.  Peak velocities of 2.1 km/s were achieved in these experiments.  The railed tubes were later replaced with a smooth bore test section of 30-mm-bore.  Both superdetonative and subdetonative experiments were carried with this smooth bore test section. 

At Tohoku University in Sendai, Japan, a 25-mm-bore ram accelerator was constructed under the direction of Prof. Akihiro Sasoh.  Low mass, high acceleration tests were carried out and ~2.4 km/s velocities were achieved.  High-speed photography through specially curved tubes was carried out.  An interferogram of the projectile penetrating a diaphragm holding pressurized nitrogen and a sequence of high speed photos of the projectile approaching the test section entrance diaphragm were taken.  

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