Lifter in a Vacuum

last updated:07 Jun 2002

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Lifter in a Vacuum (07 Jun 2002)

I got the idea for the lifter from the JNL site (see main page links). If the lifter is ever to be used as propulsion system for a space craft, its propulsion must be studdied in a vacuum. The above shows the setup I used. The vacuum chamber is from (Edmonds Scientifics) with a few modifications. I drilled 4 holes in the bottom and used bolts with rubber washere (as o-rings) to make electrical feed-throughs. The input current is measured with the yellow DVM (right), and the high voltage is measured with the black and red HV voltage probe (left). The pressure is measured with the pressure gauge from the ed-sci hand pump. I found that I could get lower pressures if I connected a second ed-sci pump in series with the first (partially shown at bottom of picture). What I did was take voltage and current measurements when input power adjusted such that the ship just lifted off the ground (and took measurements as a function of pressure). Since I can measure the weight of the ship, I can calculate power needed to produce a given force.

Download Video Lifter in Vacuum (1.6MB)

Above is the high-frequency transformer I used to power my Voltage multiplier. Drive frequency ~6.7 kHz.

This is a picture of the FET I used (NTE 2377) in a bowl of (now water) what was Ice. I set the Heat sink on Ice cubes while running the experiment because the fet would get so hot. (And believe me I went through some nice transistors before I came up with this design). At the lower pressures -30kPa, I needed an whopping 272 Watts of power input through the fet.

This is a voltage multiplier (Like ones you'd find in a TV), and mica cap for matching the load impedance (in parallel with input to multiplier circuit). The circuit works much better when matched.

Here are the results (pressure is in kPa below atmosphere, i.e. 10 kPa on the graph is 10 kPa below 1 atmosphere, 0 kPa is at 1 atmosphere , etc.). The power required for the the lifter to just lift off, increases as the pressure decreases (according to the results this does not look good, at least for use in space travel). The lowest pressure I could go to and still have the lifter lift-off, was -30 kPa. Pressures even lower caused arcing and breakdown between the HV lines. (Note: all pressures are a negative amount below atmospheric pressure. i.e 0 kPa = 1 atm pressure)

The reason why we see this decrease in lift at lower pressures is... The required current for lift-off increased at lower pressures. Required voltage for lift-off was always 20kV. Above is a plot of the impedance of the lifter as a function of pressure. The impedance drops (linearly?) as a function of pressure. This is due to break down/conduction between the conductors. There is hope though. If one studdies the Paschean curves, the impedance should increase again for very high vacuums. (since there is no longer any air to conduct the electricity) Remember Townsend Brown was reported to have had increadable results with his discs in high vacuum chambers. I just can not reach these high vacuums with my present setup.
This is a lightning like break downs at -70 kPa
This is high current arcing at -80 kPa
More diffuse arcing at -90 kPa
Even more diffuse arcing at -97 kPa. This is the limit of my present vacuum chamber
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