Naudotojas:Mantito/Todo/pdg
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I actually do some work on this with the PWFA group at USC (i'm an undergrad research assistant). It really is amazing! We can reach acceleration gradients of around 60 GeV/m, compared to something like 40 MeV/m for a normal accelerator. It works like this: 1. The electrons travel down the main linac in carefully spaced "bunches", and get accelerated to around 43 GeV over a course of ~3KM (this is at the main beam at SLAC). 2. A (in the last experiment) 1.2m long Lithium plasma "oven" is at the end of the beam, which the electrons are directed into. 3. The first, or "driving," bunch goes through the plasma, and repels all of the electrons it gets near, leaving an "empty" wake behind it, where only the positively charged ions are. 4. The positive charge behind the driving beam pulls it backwards, causing it to lose energy. At the same time, a "witness" bunch placed strategically within the wakefield gets pulled forward by the positively charged ions. The witness gains energy while the driver loses energy. 5. Voila! One bunch now has twice the energy, and one bunch now has none . . .or at least something close to that!
The main caveat is that you're upward-limited by your entering energy, so you still need a huge Linac to accelerate the bunches to begin with. This will likely get tacked on in the form of a "plasma afterburner" to a normal linac, such as in the setup at SLAC.
As far as I understand it, it doesn't work nearly as well for heavier particles (I assume you are thinking protons?). Especially ones with a positive charge. The heavy mass of the protons compared to the electrons in the plasma cloud are what allows the "wakefield" to be created in the first place. When we model this stuff, the ions move so slowly compared to the electrons that we generally just assume that they are static for the duration of the beam passing through the oven (pico-femto second range). As I mentioned earlier, this will most likely always show up as an "afterburner" that goes at the end of a traditional linac.