Modular electromagnetic railgun accelerator for high velocity impact studies.

Area of Science:

• Electromagnetic propulsion
• Materials science
• High-velocity impact testing

Background:

• The development of advanced electromagnetic accelerators is crucial for high-velocity impact testing.
• Railgun technology offers a pathway to achieving hypervelocities for material science research.

Purpose of the Study:

• To commission and characterize the performance of the RAFTAR (Railgun Accelerator Facility for Technology and Research) electromagnetic railgun.
• To evaluate the facility's capability for single-shot, high-velocity impact testing on materials.

Main Methods:

• Utilized a modular, breech-fed, rectangular bore railgun (14 × 13 mm²) with a 1.15 m barrel.
• Powered by two 160 kJ capacitor bank modules, ignitron switches, and a pulse shaping inductor.
• Employed time-of-flight technique with B-dot sensors and a shorting-foil arrangement for velocity measurements.

Main Results:

• Achieved projectile acceleration exceeding 1000 m/s for an 8g aluminum-7075 armature.
• Recorded a muzzle time of approximately 1.75 ms with a 220 kA current.
• Observed a velocity-skin-effect during the high acceleration phase in-bore.

Conclusions:

• Demonstrated RAFTAR's capability for high-velocity material testing.
• Validated experimental results against theoretical predictions, confirming optimal parameter selection.
• Identified key factors limiting railgun performance for future optimization.