Constructing and testing a permanent-magnet railgun Yangfan Wu and Dr. Tianbao Xie

Abstract A modified magnetic railgun has been built and investigated.

Permanent magnets were used to supply the magnetic field and

a car battery was used to provide the current. The projectile has

been successfully launch. The result showed the tested railgun

required significantly less current than the conventional ones.

Acknowledgements

Design

I would like to thank the Linfield physics department for granting my thesis reseach, also my faculty thesis committee for their consistent help. For Dr. Xie’s tremendously helpful guidance and ideas. Dr. Schnitzler for his corrections on my thesis and support. Dr. Murray for her efforts to keep me on track of my thesis process. I would thank my parents for my parents for their love and support.

Results & Discussion

Future Works

Introduction and Overview Railgun Applications: Weapon:

• The first Railgun was proposed

in 1944, during WWII by

Germany, as an electric anti-

aircraft gun.

• It was never built, the electricity

needed for each gun was enough

to illuminate half of Chicago.

Launch Space Shuttle:

• A two-mile-long track

• Accelerate from 0 to 1,100 mph

in 60 seconds

• $350/kg vs. $20,000/kg

Theory: • A railgun is an entirely electrical

gun that accelerates a conductive projectile along a pair of metal tacks

𝐹 = 𝐁𝐈 × 𝐋

1Department of Physics, Linfield College, McMinnville OR

•Reduce the contact resistance and friction force by making

grooves in the rails

•Change to lighter projectile

𝐅 =𝜇0𝐈

𝟐

4𝜋𝑠(sin 𝜃2 −sin 𝜃1) × L

Main Body:

Power Supply:

Bank of Capacitors: Permanent Magnetics & Car Battery:

Advantages:

i. relatively compact

ii. easily discharged

Disadvantage:

i. discharging time is only

several milliseconds

ii. Heat

a. Increase the friction

b.destructive

Advantages:

i. Longer Charging time

ii. Stable Current flow

iii. Decreased heat

Disadvantage:

i. Small current

Projectile:

Magnets

Insulators

Iron sheets

“Rarely do railgun operates with a total efficiency over 2%” (Bosscher, 2001)

VS.

Conventional Railgun:

• 𝑩 field of 1T can not achieved until 35,000 amperes current flows through the wire.

• Same amount of velocity necessitated ten 400 V, 6300 uF capacitors.

Permanent-Magnetics Railgun: • 2.4 tesla is provided by rare

earth permanent-magnetics • 12-V Car battery

Conclusions: Railguns with Permanent-Magnets is more mobile, inexpensive, energy-saving and efficient than conventional railguns.

References McNab, I.R. "Launch to Space with an Electromagnetic Railgun." IEEE Transactions on Magnetics 39.1 (2003): 295-304. Print. Pacella, Rena Marie. "NASA Engineers Propose Combining a Rail Gun and a Scramjet to Fire Spacecraft Into Orbit." Popular Science. N.p., 17 Dec. 2010. Web. 18 Apr. 2013. Vlahos, Kelley. "It's Real! Navy Test-fires First Working Prototype Railgun." Fox News. FOX News Network, 28 Feb. 2012. Web. 18 Apr. 2013. Usnavyresearch. "BAE Electromagnetic Railgun." YouTube. YouTube, 27 Feb. 2012. Web. 18 Apr. 2013. a. Copper piece

b. Spring loaded projectile

c. Modified projectile from b

Three types of projectiles have been tried throughout the experiment

(1. German soldiers during WWII http://www.english.illinois.edu/maps/ww1/photoessay.htm)

(2. Imaginary space shuttle railgun acceleration system http://www.tomsguide.com/us/NASA-Railgun-shuttle-launcher,news-9468.html)