Jeff Greason of the Tau Zero Foundation is presenting a new class of drive: Using the Dynamic Pressure of Passage through Interplanetary or Interstellar Plasma to Expel Reaction Mass at High Velocity. Jeff’s presentation is at Space Access 2019.
A plasma magnet offers one-million times the drag power to excitation power.
The magnetosphere of Neptune is not enough to stop a high-velocity electric sail. Stopping from 100 kilometers per second would take a 30G deceleration within Neptune’s magnetosphere.
There was a Centauri Dream summary of Jeff’s prior design of a plasma magnet drive.
Greason previously described using 10kW power supply to use a plasma magnet to propel a 2500 kg craft with an acceleration of 0.5g, reaching 400-700 km/s in just half a day.
Braking With a Q Drive
Jeff’s new idea is to take the energy from the passage through the plasma of space to use on the reaction mass that a spacecraft is carrying. This the Drag-powered reaction: Q-Drive.
Harness externally supplied energy to move internally-supplied reaction mass.
Carry the reaction mass onboard use ram air turbine to extract energy (cause drag) to expel reaction mass (making thrust).
Idealized with no losses:
Exhaust Velocity = Windspeed
Specific Impulse = 0.5 windspeed
Mass Ratio = ((Initial Windspeed+ delta V)^2)/(Initial Windspeed) ^2
This is conservation of kinetic energy.
The Solar wind speed is 450 kilometer per second on average.
Q-drive operates to extract the energy (IBIS paper coming)
0.05 meter per second squared deceleration credible with existing materials and power sources.
Accelerate to 155 kilometer per second outward no mass spent
At the halfway point switch Plasma magnet to propelling reaction mass forward. At 155 km/s the relative wind speed is 295 km/second on average. Mass ratio to brake at Neptune is 2.3.
Achieve orbit around Neptune in one year.
This is 12 times faster than Voyager.
Allows for 20 kilowatt per kilogram specific power maneuvers.
At the orbit of Earth, 1 astronomical unit (AU) from the Sun, typical solar wind densities, flow speeds, and temperatures are on the order of 8 protons per centimeter cubed, 440 km/s, and 1.2 × 105 K, respectively; however, the solar wind is highly variable in both space and time.
SOURCES- Live coverage of Jeff Greason at Space Access 2019, Centauri Dreams
Written By Brian Wang, Nextbigfuture.com
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I think the idea here is a two function sail, riding solar wind out, then extracting power from the sail for an ion drive at stupidly high power in thrust vectors that a sail would suck at.
I’d have to see the details of how the incoming energy gets transmitted to the reaction mass. If the energy is actually being produced in the form of electrical power, I don’t see how it beats the engine only thrust to mass ratio for an ion engine.