Proton Plasma Wakefield Accelerators

[Joe D]

Why do all wakefield accelerators seem to use either electrons or positrons? Is there any reason you would have difficulty creating a laser driven proton plasma wakefield accelerator? (that is, in comparison to an electron accelerator) Thanks.

 

[mfb]

Laser driven plasma wakefield accelerators are one of the three main options investigated, protons and electrons are the other two.
What gives you the impression lasers wouldn't be used?

 

[Joe D]

Perhaps my wording isn't correct, I've only been reading about wakefield accelerators for a week or so. I'm wondering if there is a reason I haven't seen wakefield accelerators used to accelerate protons.

The closest thing I've seen is CERN's AWAKE project that uses a 400 GeV proton beam to aid in accelerating electrons

 

[Joe D]

Basically, I'm trying to figure out if a wakefield accelerator might be a viable way to create a (relatively) inexpensive 1 GeV proton source.

 

[Vanadium 50]

Protons are slow, and the electrons are fast. It's hard to set up a wakefield to transfer energy between particles of very different velocities.

 

[mfb]

Ah, for the accelerated particles.
Acceleration needs a high speed of the accelerated particles, and protons would need a really high energy to start with. The drive beam would need even more energy, which limits the application to particle physics research, and then you run into problems. There are 400 GeV proton accelerators that could be used for (interesting) 200 GeV++ electron beams, but no 400 GeV electron accelerators that could be used for (quite boring) 200 GeV++ proton beams.

 

[ZapperZ]

Perhaps my wording isn't correct, I've only been reading about wakefield accelerators for a week or so. I'm wondering if there is a reason I haven't seen wakefield accelerators used to accelerate protons.

The closest thing I've seen is CERN's AWAKE project that uses a 400 GeV proton beam to aid in accelerating electrons

As has been mentioned, it takes a lot more "power" to cause a significant increase in energy when accelerating heavier particles. It isn't impossible, and the scheme for wakefield acceleration can be applied to electrons as well. But you need to understand that this is still a research-front experiment. So people will tend to show proof-of-principle experiment using something simpler before moving on to something more difficult. After all, the first accelerators before they were perfected were all done on electrons.

Once we have an ability do show this scheme with electrons, then there will definitely be a concerted effort to accelerate protons and ions. In fact, there are already people looking into this, with this one being an example:

http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.115.064801

BTW, just so you know, accelerator physics is not automatically equal to "high energy physics". More than 90% of accelerators in the world have nothing to do with high energy physics experiments.

Zz.

 

[Joe D]

Awesome thanks. Zz, I understand your point. I actually didn't have high energy physics in mind when I was thinking about accelerators. I was just wondering if wakefield accelerators could be used for a spallation neutron source. I just posted it in the high energy physics section since it seems to be where the plasma physicists would be hiding. Thanks again.

 

[ZapperZ]

Awesome thanks. Zz, I understand your point. I actually didn't have high energy physics in mind when I was thinking about accelerators. I was just wondering if wakefield accelerators could be used for a spallation neutron source. I just posted it in the high energy physics section since it seems to be where the plasma physicists would be hiding. Thanks again.

Also note that not all Wakefield accelerators involve plasmas We have metallic and dielectric-loaded Wakefield accelerators. CLIC and the Argonne Wakefield accelerator are two such examples.

Zz.

 

[Joe D]

Zz, that's good to know, I hadn't realized that. I had been looking at what SLAC and the Texas Petawatt laser were up to.

 

[Joe D]

So I suppose the conclusion is that my dreams of a tabletop spallation neutron source won't be coming true for a while, at least until the technology improves. I guess I'll continue use Oak Ridge for those purposes.