| Chemical vs The exhaust velocity of modern chemical rockets is at least one order of magnitude too small for the needs of fast interplanetary travel. The amount of propellant that must be carried along today constitutes most of the ship's mass and hence leaves little room for useful payload. Its flow rate is so high, that the rocket ship spends it all in a few short bursts. That does not lend itself well for human missions.  |
Plasma High exhaust velocity can be achieved by the use of plasma. The temperature of a plasma starts at about 10,000° C. But present day laboratory plasmas can be a thousand times hotter. These temperatures are comparable to those in the interior of our Sun. No known material could survive direct contact with such plasma. Fortunately, plasma responds well to the presence of electric and magnetic fields. A magnetic channel can be constructed to both heat and guide plasma, without ever touching material walls. Magnetized plasmas are envisioned to some day generate abundant energy on Earth by controlled thermonuclear fusion. |
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