Sunday, September 16, 2007

The Plasma Revolution

The title is a bit misleading. This article in this week's Nature (v.449, p.133 2007) is on the use of plasma for particle acceleration. I have written about the advancement in this field a few times already (read here, here, and here).

It's a good review article on the use of plasma as a medium for the wakefield generated either using charge particles or laser. However, it has some misleading and incomplete parts to it. For example:

A handful of groups are working on a new way to accelerate particles - known as wakefield acceleration - that should not only help push physicists towards the next energy frontier, but also provide affordable, table-top accelerators that could revolutionize cancer treatment.

The technique involves passing either a laser beam or a beam of particles through a plasma....

Nothing wrong with this, but the author made it sounds as if the ONLY technique for wakefield acceleration is using plasma as a medium. He is ignoring another technique that is also making quite a good progress here, the use of dielectric medium instead of a plasma. The dielectric-loaded accelerating structure, such as those done at Argonne's Wakefield Accelerator group, has recently shown the ability to generate and withstand an accelerating gradient of 100 MV/m. Now it may not be of the same gradient as those achieved using the plasma technique. However, this technique has several advantages, such as the obvious ability to be staged.

The wakefield technique, both using plasma and dielectric media, has shown promising advancement for a new acceleration technology that might allow for the next generation of particle accelerators. The next few years should be very exciting.

Edit: A new press report on the AWA dielectric-loaded gradient can be found here.


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