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20 Kilowatt Plasma Blaster Engine Design
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From: Greg Leyh [SMTP:lod-at-pacbell-dot-net]
Sent: Wednesday, June 24, 1998 12:31 PM
To: Tesla List
Subject: Re: 20 Kilowatt Plasma Blaster Engine Design
Scott Stephens wrote:
> So what about my possibly clever idea for a flame-excited Tesla Coil? Too
> boring and lame? Maybe I was too flippant and irrelevant to be taken
> seriously by the list.
It's more likely that folks such as myself don't understand
exactly what you are proposing... Is this some reciprocal sort
of engine that compresses the fuel magnetically, combusts,
then MHD's the combustion energy to and from the TC at its Fres?
> In this (second) design iteration, I come to the conclusion that 1 joule in
> a .1mH inductor can put a 50 atmosphere (700psi) squeeze on a 12cm plasma
> current loop for 10uSeconds.
>
> I would most likely spray propane-air from a propane torch or bunsen into a
> microwaved plasma, around 2cm radius, in around 10 microseconds. This plasma
> will be pulsed, oscillating in volume, around 2000 times/second.
>
> Fuel compression energy =1 Joule
>
> Pulse capacitor: E=.5cv^2, 1J+=1.4KV,1uF (maybe could use a cheap, small 10J
> photo-flash caps if ESR, pulse width and fuel character allow, and a step-up
> winding on inductor)
>
> Inductor aka Tesla Coil (magneto-sonic plasma transducer; pulsed by cap
> through triggered spark, Xe strobe tube or SCR)
> E=.5 li^2 = 1J=.5*.1mH*(140A)^2,
> V= L di/dt = , 1.4KV=.1mH dI(140A)/dt (10 microseconds)
> N=(L(9A+10B)^.5)/A; L is 100uH; A is 1" Rad; B is 1" Len; So N = 43 Turns
> B= V T 10^8/NA= 1400V*10^-5*10^8/43*PI*2.54^2=1.6Kgauss or .16 Tesla
>
> K notwithstanding, I'll assume a 43:1 step-down ratio, and a pretty low < .1
> ohm plasma resistance, and .1uH for a 1" radius plasma-loop inductance:
>
> Plasma I = BNA/L10^8 = 1.6Kgauss*1*20cm^2/.1uH*10^8=3200A (close enough to
> the 33:1 xformer assumption (4600A)
> Perfect-coupling xformer step-down estimate 33:1 * 140A = 4.6KA
> Realistic .5 K suggests 2000A induced current, so
>
> F(dynes)=Bil
> =1.6Kgauss*2000A*(2*PI*2.54cm)= 51 mega-dynes/cm^2 = 50 atmospheres
> Plasma Vol.=4PI(2.54^3cm)/3=68cm^3 or around 70cc
>
> So for 1 Joule + of energy from my capacitor, I put maybe a 700 psi squeeze
> on my 70cc plasmoid in 10 microseconds in a 1.6 Kilogauss field using my
> .1mH 43 turn, 2.5cm radius, 2.5cm long air core coil.
>
> If my resonant cavity can accept a ferrite transformer core, and I can have
> a K near 1, pulse it around 50uS, and fuel temperature and plumbing
> permiting, a very nice compact motor could be constructed, with
> semiconductors for realistic effiecency :-)
>
> Propane: .5kg/l; 46MJ/kg
>
> For 10% efficiency (10J/pop), I'll want to burn .22mg and .00044 l per pop;
> For 2000 pops/second = 1ml/second propane flow; at 5% explosive limit
> mid-range, air volume = 20ml/second; plasma core around 5cc so gas flow rate
> is .05 meters/second.
>
> Reactor power is 20 kilowatts. 2 Kilo-watts sustain magnetic oscillations,
> and the rest make heat, with a howl like a banshee }:-O
>
> My latest effort has been to search for EM codes to design the resonant
> cavity. NEC uses the method of moments technique to calculate fields, which
> may not be good for microwave cavities. APLAC (free version) uses FDTD, but
> is too limited. And none model ferrite, which probably is too complicated
> and material-dependant anyways. And what will the plasma E-eff be as the
> field is pulsed?
>
> The image of a metal, bi-conical center, with gas inlets/exhaust ports,
> surrounding a ferrite core, all in a TEM 10 cavity comes to mind.
>
> Scott Stephens
--
-GL
www.lod-dot-org