Scientists tout civilian laser-fusion plans

A group of European scientists has put forward a proposal for a £500m facility to research new approaches to laser fusion that could potentially be built in the UK.

The facility, provisionally called HiPER, would be civilian-run, and as well as pursuing research into fast-ignition laser fusion, would also be available for other experiments in astrophysics as well as nuclear and atomic physics, the group says.

The group, which represents seven European Union member states, was set up by Henry Hutchinson of the Rutherford Appleton Laboratory in the UK. It says the facility could be in place and working by the middle of the next decade, PhysicsWeb reports.

The goal of the research would be to go beyond breaking even on the energy-in/energy-out equation and achieve high energy gains. This is a vital milestone on the road between merely demonstrating ignition, and building a workable demonstration reactor.

Hutchinson told PhysicsWeb: "The energy problem is sufficiently urgent that we cannot afford to ignore different approaches to fusion."

Laser fusion research is being pursued internationally because of its potential to supply large quantities of clean energy. There are two main approaches to confining the plasma generated during the reaction: magnetic or inertial confinement.

Currently, both approaches are being studied at various sites around the world. Magnetic confinement is the be researched by the international team ITER, and inertial confinement is being investigated at the National Ignition Facility (NIF) in the US and the Laser Mégajoule (LMJ) in France. Both of these facilities are primarily designed for nuclear weapons research, and have relatively little time to devote to other scientific research.

The basic principles are relatively simple to lay out: a high energy laser is used to heat and compress a small amount of deuterium, a stable isotope of hydrogen. When the deuterium gets sufficiently hot, the outer layers detonate, sending a shockwave towards the centre of the sample.

This shockwave, if it is large enough, triggers thermonuclear ignition - i.e. the nuclei in the deuterium fuse, releasing helium and neutrons, and a large quantity of energy. This in turn ignites a chain reaction in surrounding fuel, and the resulting energy could then be used to generate electricity.

By convention, the same laser is used both to heat and compress the sample of deuterium. In fast ignition, there are two lasers, one to handle each stage separately.

HiPER would combine a 200kJ long pulse laser, for compression, and a 70kJ short pulse laser for heating. Hutchinson says this approach requires less laser energy than the conventional approach, making it markedly cheaper. ®