Reply To: T-shirt designers unite and take over

[Jolly Roger]

From “DREAD Weapon System” thread:

Brian H wrote:

I never thought of that. But yes, an incredibly powerful focus fusion laser could theoretically be used to accelerate a solar sailing craft to Mars. Or beyond Neptune, Pluto, even beyond the solar system.

I don’t see why you’d bother. Take along a tonne of decaborane and an FF generator or ten, harvest a bit of hydrogen along the way from the interstellar medium, and you could get far more power and acceleration and control and options. With a solar sail, you can’t wander out of the beam or you’re helpless until a signal can be aimed back to the source and the laser re-directed. Braking is tricky, too. You have to pop a counter-mirror out front and turn the sail around to get the bounce-back, or SLT.

You may find this site of interest:

http://www.ess.washington.edu/Space/propulsion.html (Advanced Electric Propulsion)

(minor edit for clarity)

Advanced Electric Propulsion

Chemical rockets have limited application for space applications due to the fact that the fuel is relatively slow (low specific impulse) relative to the speeds needed to move efficiently about the solar system. As a result, chemical systems are massive, and the trip times for missions are very long. Research at UW (University of Washington) in this area is for the development of faster propellants that can provide substantial reductions in cost and trip time. To achieve these efficiencies plasma systems (i..e. charged particles) are required where electric and magnetic fields can be used to accelerate the plasma propellants to speeds more than an order of magnitude faster than can be achieved by chemical rockets. The systems below detail devices under active development:

High Power Helicon (HPH) is an electrodeless plasma thruster that is able run at kW to 100’s kW to produce thruster levels as high as several Newtons (N) of force, at high power and gas efficiency.

Mini-Magnetospheric Plasma Propulsion (M2P2) is a system that can leverage energy from the solar wind to augment the onboard propulsion for spacecraft while minimizing the spacecraft power requires. Potential for radiation shielding is still under investigation.

PlasmaMagnet has the ability to create large magnetic systems without the need for any pre-existing magnets. These systems provide new capabilities for plasma sails and radiation shielding.

MagBeam combines the key features of M2P2 /PlasmaMagnet with high power beam plasma sources such as HPH to produce a system where large orbiting spacecraft can be used to push payloads between the planets with very little cost and thereby facilitate a permanent human presence in space.

(edited)
The MagBeam System is a plasma-magnetic equivalent to the Laser/Solar Sail system above, but has the advantage of being self-aiming, adjustable at the payload, and reversible (push or pull). All the components of the system need power, which Focus Fusion (FF) could provide.

An FF could also serve directly as a plasma source. However, it is probably more useful as the power source of the HPH. Even though FF has a high specific impulse (high velocity), it does not have the high mass throughput, hence Thrust, of an HPH.

BTW, 1 N thrust = ~ 0.1 g acceleration per kilogram of payload. A 100-(metric)ton craft would need about 1,000,000 Newtons (1MN) thrust for 1 g.

NB: M2P2 /PlasmaMagnet can brake at the destination by interacting with a planet’s magnetosphere or a star’s solar wind.