Big power supply

"In order to direct the plasma resulting from the explosion towards the rear of the vehicle a magnetic nozzle is utilized. The MMO team utilized particle trajectory (developed at the University of Washington) and MHD (MACH2) based analysis to investigate nozzle characteristics and establish a baseline suitable to the MMO vehicle concept. The final baseline nozzle, produces 1,870kN of thrust,

16,000 seconds of specific impulse and a nozzle efficiency of 87.1% at a yield of 340GJ per implosion.

It consists of 5 coils distributed over 11 meters with coils preferentially clumped near the axis, each carrying 10 MA of current. The total array mass is approximately 200 metric tons.

The power supply for the Z-pinch implosion should provide a current evolution with approximately a

unimportant since the implosion interrupts the current. The electrical power requirements for the magnetic nozzle are determined by the final nozzle design (magnetic field and coil locations). The power requirements of the two systems are sufficiently different that individual power supplies should be tailored to each system.

The high currents and short rise times required by the implosion can be generated by charging a capacitor bank in parallel to a lower voltage and then using switches to connect the capacitor in series. This configuration is called a Marx bank. The Marx bank

170 kV. The choice was driven by easily available capacitors at the rated voltage and capacitance. It is envisioned that the switches will be high voltage gap switches with low inductance.

The charge supply is isolated from the capacitors through two 250 ? resistors for each capacitor. The energy required for each implosion is CV2 /2 or 72 MJ. At a pulse rate of 1 Hz, the power requirement is 72 MW."

Reply to
bitrex
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MA = milliamps? Oh, no, it means MEGA-AMPS!

Jon

Reply to
Jon Elson

I like the "10 500uF capacitors each charged to 170kV" part.

"The choice was driven by capacitors commonly available"

Commonly available to who?!

Reply to
bitrex

Utopia Planitia Orbital Shipyards?

Reply to
bitrex

Ah, maybe ordered from the catalog they used in "This Island Earth" -- the one where the pages were printed on metal? (Google says, "Electronic Service, Unit #16")

(at best a B-grade 50's sci-fi film with effects that were advanced for the mid 50's, but have definitely not aged well)

Reply to
artie

One biggish Marx that I saw, the charging resistors were clear plastic hoses filled with water, with some copper sulfate dissolved. Nice blue color.

One of my many crazy ideas is to charge up some big ceramic doorknob caps, one at a time, and physically stack them as each is charged. Say, 30 caps at 30KV each.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

Folks like Sandia Labs, where they have the Z machine. They zap a target with multiple mega-amps from banks of Marx generators. Produces temperatures close to what you get in a nuclear weapon detonation.

Jon

Reply to
Jon Elson

You can probably make a real Marx generator with little extra work and MUCH less personal risk. Just stack the caps in a zig-zag arrangement, add some super-high value resistors for the charging, and some sheet aluminum or whatever as the spark gaps to put them in series. When the first one breaks over, it starts a cascade to fire them all.

Jon

Reply to
Jon Elson

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