Download CoilGun PPT

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 Verne et 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
Eraser,
How does it work?
force
field
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:
force
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
Resistance R=0.3
Inductance L=?
mF
W
Inductance
200
0.05
Inductance L:
0.04
Depends on the position
of the projectile
150
0.03
100
0.02
50
Force:
0
0.01
-50
0.00
-100
-0.01
-150
-200
-10
0
10
20
L' (H/m)
L (H)
250
F= L’·I2
Force maximum occurs
where the inductance
variation has a maximum
30
position (mm)
Position:
Projectile tip
0
10
20
30
position (mm)
40
- 5 mm inside coil
1500
Force, mass...
I (kA)
Coil current
1000
500
F=ma~I2
a (x1000 m/s2)
0
15
Projectile acceleration
10
5
v=at
v (m/s)
0
30
Projectile velocity
20
10
a 2
s= t
2
s (mm)
0
104
103
102
101
100
10-1
Distance covered by
the projectile
Coil center
Coil mouth
100
101
102
103
time (s)
104
105
106
Current, charge
Capacitance C=8.8
mF
Resistance R=0.3
W
Inductance L=150
H
Voltage U=450
~4 Coulombs
discharge through
the coil
V
Charge Q=C·U=4
C
Energy E=½C·U2=900
J
~ 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
Electric
C
E= U2
2
~ 900 J
Diminutive efficiency,
kein Schwarzenegger...
Kinetic
m
E= v2
2
~ 12 J

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