Adam Crowl, crowlspace, points out that with the 6.3% of light speed exhaust velocity from Winterbergs deuterium fusion rocket design means a 120,000 ton starship attached to 12,000,000 tons of deuterium can do a delta-vee of ~0.2 c (20% of lightspeed). This would be using the two stage configuration of the Project Daedelus (which was also based on Winterberg ideas). Daedelus had exhaust velocity of 3% of light speed.
With an efficient magnetic sail that means the journey speed approaches ~0.2 c, albeit with the mass-penalty of the sail. Perhaps a plasma-magnet can be formed at such speeds, with a quite different decceleration profile to the mag-sail, since the artificial magnetosphere balloons to match the plasma ram-pressure. Essentially the size goes up as the relative speed goes down, thus allowing a more-or-less constant braking force. A decceleration of 0.1 m/s2 will bring the vehicle to a halt in ~19 years over about 1.9 light-years from 0.2 c.
From Winterberg’s paper: Neutron entrapment in an autocatalytic thermonuclear detonation wave is a means to increase the specific impulse and to solve the large radiator problem. The maximum exhaust velocity becomes 6.3% of light speed.
Daedalus would be constructed in Earth orbit and have an initial mass of 54,000 metric tons, including 50,000 tons of fuel and 500 tons of scientific payload. Daedalus was to be a two-stage spacecraft. The first stage would operate for two years, taking the spacecraft to 7.1% of light speed (0.071 c), and then after it was jettisoned the second stage would fire for 1.8 years, bringing the spacecraft up to about 12% of light speed (0.12 c) before being shut down for a 46-year cruise period. Due to the extreme temperature range of operation required (from near absolute zero to 1,900 K) the engine bells and support structure would be made of beryllium, which retains strength even at cryogenic temperatures. A major stimulus for the project was Friedwardt Winterberg’s fusion drive concept for which he received the Hermann Oberth gold medal award.
This velocity is well beyond the capabilities of chemical rockets, or even the type of nuclear pulse propulsion studied during Project Orion. Instead, Daedalus would be propelled by a fusion rocket using pellets of deuterium/helium-3 mix that would be ignited in the reaction chamber by inertial confinement using electron beams. 250 pellets would be detonated per second, and the resulting plasma would be directed by a magnetic nozzle. Due to the scarcity of helium-3 it was to be mined from the atmosphere of Jupiter via large hot-air balloon supported robotic factories over a 20 year period.
The second stage would have two 5-meter optical telescopes and two 20-meter radio telescopes. About 25 years after launch these telescopes would begin examining the area around Barnard’s Star to learn more about any accompanying planets. This information would be sent back to Earth, using the 40-meter diameter second stage engine bell as a communications dish, and targets of interest would be selected. Since the spacecraft would not decelerate upon reaching Barnard’s Star, Daedalus would carry 18 autonomous sub-probes that would be launched between 7.2 and 1.8 years before the main craft entered the target system. These sub-probes would be propelled by nuclear-powered ion drives and carry cameras, spectrometers, and other sensory equipment. They would fly past their targets, still travelling at 12% of the speed of light, and transmit their findings back to the Daedalus second stage mothership.
Marx Generators exist and Winterberg proposes putting one hundred of them in series to power a gigavolt fusion power system. Winterberg came up with the theory for the Z-pinch system that is being tested at the research labs now.