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Delve into the concept of electromagnetic launch technology for space travel from Earth to the Moon, exploring the mechanics of coilguns, railguns, and mass drivers. Learn about the factors influencing projectile acceleration, velocity, and distance covered by the projectile, along with the principles of capacitance, resistance, inductance, voltage, charge, and energy in electromagnetic launch systems. Discover the efficiency and potential of EM guns for propulsion in outer space.
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T. Vuletić, Institute of physics, Zagreb Višnjan S3++ 2011 EM launch Or We’re out! What now?
T. Vuletić, Institute of physics, Zagreb Open day 2010 Space elevator Or How do we get out?
Earth’s gravity well C,D: 1st cosmic velocity V12/R=g V1=7.9 km/s E: 2nd cosmic velocity V22/2R=g V2=11.2 km/s
Chemical launch: Newton, Jules Verneet al. Gas expansion V=1-4 km/s : insufficient! there’s also the atmospheric drag...
Moon’s gravity well Moon: 1st cosmic velocity V12/(R/2)=g/6 V1=2.2 km/s 2nd cosmic velocity V22/R=g/6 V2=3.1 km/s
EM launch: Moon shallow well + there’s no air-drag read... R.A. Heinlein: The Moon is a Harsh Mistress
EM launch: Moon watch... “Moon” by Duncan Jones
Logistics orbit: Lagrange points Idea: G.K. O’Neill and his S.S.I. “father” of the particle accelerator read... R.A. Heinlein: The Moon is a Harsh Mistress
EM gun while we’re still here
force field force How does it work? Mass Driver: Electromagnets repel or attract and cary the projectile Railgun: Rails are shorted by the projectile – current in this circuit forces the project out Coilgun: Electromagnet attracts the feromagnetic projectile!
EM gun solid-state relay capacitors railgun coilgun Coil, 30 turns, 4 layers, 1 mm wire Capacitors, 450V, 8.8mF
RLC circuit Damped harmonic oscillator Solving for the Current: underdamped damping resonant frequency overdamped critically damped
RLC circuit Damped harmonic oscillator Capacitance C=8.8 mF Resistance R=0.3 W InductanceL=?
Inductance Inductance L: Depends on the position of the projectile F= L’·I2 Force: Force maximum occurs where the inductance variation has a maximum Position: Projectile tip - 5 mm inside coil
1500 Coil current 1000 I (kA) 500 0 15 Projectile acceleration a (x1000 m/s2) 10 5 0 Projectile velocity 30 20 v (m/s) 10 0 4 10 Distance covered by the projectile 10 3 2 10 Coil center s (mm) 1 10 0 10 Coil mouth -1 10 0 1 2 3 4 5 6 10 10 10 10 10 10 10 time (ms) Force, mass... F=ma~I2 v=at a2 s= t2
Current, charge Capacitance C=8.8 mF Resistance R=0.3 W InductanceL=150 mH Voltage U=450 V Charge Q=C·U=4 C Energy E=½C·U2=900 J ~4 Coulombs discharge through the coil ~ kiloAmps in milliseconds!
Velocity 2.5 m 100 msec 20 msec 0.5 m 0 msec V=25m/s V=90km/h 0.0 m
Energy 25 g Kinetic ~ 12 J Electric ~ 900 J m2 C2 E= v2 E= U2 Diminutive efficiency, kein Schwarzenegger...
EM gun Machine & electronics shop Institute of physics: I. Čičko, B. Kiš, A. Vojnović Thanks: R. Beuc, Đ. Drobac, B.Erjavec, M. Prester, K. Salamon Take a look: www.youtube.com/user/fizika123 coilgun.info www.powerlabs.org audacity.sourceforge.net Keywords: coilgun, railgun, mass driver, EM launch