Electromagnetic Coil Gun

Participants: 

Kin Chan
Gradeigh Clark
Daniel Helmlinger
Denny Ng

Advisor: 
Prof. Sigrid McAfee



Goal & Motivation
• To design and comprehend the governing physics behind a coil gun.
• Understand why coil guns have not seen widespread use in real world applications.
• Present a viable alternative to traditional nail guns.

Design Overview
• 3 stages of coils for greater projectile acceleration.
• High voltage capacitors (400V) are charged by a boost converter circuit used to provide the necessary amount of current to propel the projectile.
• A microcontroller is used with a photosensor to provide a feedback loop to activate/deactivate each stage as the projectile passes through them.

How Does It Work>
• A large pulse of current is used to energize each solenoid (coils of wire wrapped closely together).
• The Biot –Savart Law guarantees the generation of a magnetic field due to the presence of electrical current; a tight packing of these coils allows for a uniform distribution of the field along the coil’s axis and a non-uniform distribution at the face.
• The projectile will go into the coil and will have the tendency to stay in-side of it due to the induced magnetic field.
• To ensure the projectile moves forward inside the barrel, each stage have to be “turned off” as soon as the tip of projectile reaches the magnetic center of the coil.
• The ferromagnetic projectile has to have a certain weight and size to max-imize muzzle velocity.

Results
• Booster Converter requires approximately 30 seconds to charge up the capaci-tor to ~390 V with a 12 V input.
• Each solenoid is comprised of 480 turns (8 layers with 60 turns each) made out of 20 AWG copper wire.
• Coil Gun is capable of firing projectiles at a speed of ~100 m/s at full charge.
• Final prototype cost $ 125.13 weights ~15 lbs.