MaxFeLaser plasma electron accelerator
Physicists have set a new record for the acceleration of electrons by laser-produced plasmas. A team led by Karl Krushelnick of Imperial College in London has accelerated electrons to energies of 300 MeV - a third higher than the previous best - by focusing a high-power laser into a jet of helium gas (Phys. Rev. Lett. 94 245001). However, they discovered that the mechanisms by which the electrons are accelerated changes as the laser intensity is increased.
Recent experimental results with MaxFelasers have demonstrated the generation of energetic electron bunches (energy spread < 10%) in the 100s of MeV to GeV energy range. The availability within different options in terms of length/energy will provide a unique opportunity to explore this field over a wide parameter, with a view to creating stable strong electromagnetic fields generate intense laser interaction with plasma could form the basis of a new generation of extremely compact MHD generators.
Conventional accelerators have to be hundreds of meters or longer to accelerate particles to energies in the GeV range or higher. MaxFeLasers produce plasmas which the laser directly accelerates the electrons form the basis of next-generation "table-top" accelerators because they can support electric fields that are many times stronger than those produced in traditional accelerators.
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The claim that this electron accelerator can power a car is a violation of the conservation of energy. Electron interactions with the target’s electron cloud (thorium in this case) emit x-rays, while electron interactions with thorium nuclei emit Bemsstrahlung; adding the energies of these emissions yields a net loss of energy due to shielding effects and quantum inefficiencies. Your engine has to output more energy than its input in order to move the car down the road (or, more generally, to power a turbine). That’s why nuclear fusion reactors aren’t commercially viable.
ReplyDeleteThe only way to extract a net gain of energy from thorium is to convert it to a fissile isotope, like U-233 via, radiative neutron capture, then release the excess energy stored within the gluon field via a neutron-fission reaction. That’s why modern nuclear ADSs (accelerator-driven systems) only yield a net gain of energy (i.e. energy output exceeds energy input) if nuclear spallation occurs, typically using a proton accelerator (not electrons) into a lead-based target. The resulting spallation emits neutrons, which allows for a source-driven sub-critical sustainable nuclear fission chain reaction.
As an advocate of thorium fuel, I am disappointed that this article was allowed into the public forum.