There have been two recent impressive results on using the laser-plasma wakefield technique to accelerate electrons. The first was the paper by Wim Leemans and company at Berkeley. In this technique, they claim to have achieved an acceleration up to 1 GeV in just 3.3. cm.
The second was just published this week in Nature. Victor Malka group at Palaiseau Ecole Polytechnique has managed to stabilize this type of acceleration mechanism and produced a reliable and highly controllable scheme.
These two are terrific results in the effort towards an advanced accelerator technique. There are, of course, other acceleration technique competing with this, such as the dielectric-loaded structure which also uses wakefields generated in the dielectric.
The only issue that has yet to be addressed in the laser wakefield technique is the amount of charge that is accelerated. In these experiments, a charge of the order of pC (pico Coulombs) per bunch is typically the amount that is accelerated. This is considerably smaller than the "standard" that is required for what is known as a "high brightness" beam, which is 1 nC at 1 mm-mrad emittance. I think FEL (free electron laser) facilities would require charge bunches of around such a value.
I hope they can scale up their experiements to be able to accelerate larger amount of charges that would make such a technique practical.
Zz.
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