Historical research guide · 0883 · 1975
Production of dense thermonuclear plasmas by intense ion beams
Friedwardt Winterberg
In one minute
Friedwardt Winterberg, writing from the University of Nevada in Reno, takes on the practical question behind every fusion scheme: how do you deliver an enormous amount of energy into a very small volume, very fast? In 1975 the two candidate drivers were laser light and beams of relativistic electrons. Winterberg proposes a third — intense beams of heavy ions moving slowly — and the whole argument turns on that slowness. A slow beam can be compressed along its own line of flight, so the pulse that reaches the target is far shorter than the pulse that left the accelerator, and its power is higher by perhaps several orders of magnitude. Slowness pays a second time as well. Because a slow beam can be built up gradually over about a millionth of a second rather than all at once, it can be driven by cheap inductive energy storage rather than an expensive fast capacitor bank — and where capacitors are used, the beam can simply be pulsed from the upper terminal of a Marx generator.
Connection
Chapter 12 is the energy-substrate chapter: every architecture on this site needs a small, dense source of energy before anything else, and this is one of the founding papers of the driver line that became heavy-ion inertial fusion. Chapter 9’s dense, self-holding plasma knot is exactly what a compressed beam of this kind is built to make.
From the source
The design requirement for a very high density plasma is stated at the outset and is the constraint the whole paper answers to: large energy accumulation within a small volume. Everything that follows is a way of meeting that one condition with the accelerator technology of the day.Abstract, opening sentence
Winterberg proposes intense non-relativistic beams of heavy ions as the driver, offered explicitly as an alternative to the two drivers then under development — laser beams and relativistic electron beams. That choice of a slow, heavy, many-times-charged projectile in place of light or fast electrons is the paper’s central move.Abstract, second sentence
Because the ion velocities are relatively low, the beam can be compressed along its own axis. Winterberg’s estimate is that this axial compression shortens the duration of the beam pulse and raises the beam power by perhaps several orders of magnitude — the pulse that arrives at the target being far more concentrated than the one the accelerator produced.Abstract, third sentence
The same low ion velocity makes it possible to build the beam up slowly, over roughly one millionth of a second, before it is axially compressed and delivered to the target. The slow build-up is not a side effect but part of the design: it separates the timescale on which energy is gathered from the timescale on which it is delivered.Abstract, fourth sentence
That long build-up time is what makes the scheme affordable. Winterberg argues it may permit cheap inductive energy storage devices to drive the beam, rather than the fast capacitor banks the other drivers require; and where capacitors are used, the beam can simply be pulsed with the upper terminal of a Marx generator. What to watch: this is a driver-economics argument set out in 1975, and the measurement that settles it is the cost and repetition rate of a heavy-ion driver actually delivering compression on target.Abstract, final two sentences
The way in
https://doi.org/10.1088/0032-1028/17/1/006How to cite it
Friedwardt Winterberg (1975) Production of dense thermonuclear plasmas by intense ion beams doi:10.1088/0032-1028/17/1/006