Tuesday, July 29, 2008

AAC08 Day 2

I was asked this earlier, and I'll mention it again if someone missed the comment. The plan is for all the presentation given at this workshop to be available on the AAC08 webpage... eventually. Some sooner than later. So if you look at the workshop page often, I'm sure it'll appear somewhere. I'm guessing there will be an active link in the Program page, linking each talk to the presentation, but that's just my guess. You can already see the abstracts of the Plenary talks there.

And now, on to Day 2.

The morning Plenary session started off with Ralph Fiorito of Maryland, talking about Particle Beam Radiation Diagnostics. The problem with generating electron beam is that, how do you know what you have generated as far as its property is concerned? That's where we have various diagnostics techniques to measure things ranging from the beam emittance, bunch length, size, etc.. etc. Some of these properties are not very easy to obtain, since the electrons themselves can interact in unpredictable ways with the device measuring it. So the diagnostics isn't trivial. Fiorito described 2 different channels for charged particle radiation concepts: (i) transition radiation and (ii) diffraction radiation. He then presented direct application of incoherent and coherent radiation: near field imaging (spatial distribution) and far field imaging (angular distribution).

The next speaker was Matt Zepf of Queen's University. He presented a slightly different topic than the majority of what the attendees are used to - Laser Acceleration of protons and ions. Most of us here are more familiar with electron acceleration. He presented the physics and technology of proton/ion acceleration, and how this differ from electron accelerators.

The last speaker for today Plenary session was David Bruhwiler of Tech-X. He talked about New Development in the Simulation of Advanced Accelerator Concept. Basically it is modeling various acceleration scheme, such as laser wakefield acceleration, electron beam-driven plasma wakefield, etc.

This gives me a terrific segway into one important aspect of the accelerator physics field. Many of the structures that have to be built are often either big, complicated, expensive, time-consuming, or a combination of all of these. We can't simply build one and test it, and if it doesn't work, build another one. We have to try and build one that will do close, if not exactly, what we want, or else we have spent a lot of money and effort in building something useless. That's why a huge section of accelerator physics is computer simulation and modeling. The computational aspect of accelerator physics is extremely crucial in our ability to design and simulate the various structures that we want to build first before we build it. It is only when the various numerical codes and packages can give us the confidence that we have designed something that can possibly work do we build it and test it to confirm that our simulation was accurate.

The point here is that there's a tremendous opportunity for someone who is interested in computational physics to be extremely valuable in this field. I don't think many people, especially students, realize that.

Back to AAC08.

The late morning and afternoon sessions signal the start of the "backbone" of the AAC workshop - the Working Group sessions. This is where participants break off in various working groups centered on specific areas within accelerator physics (see the webpage for the list of all the working groups).

I went into the High Gradient Structures working group where the morning and afternoon sessions were dedicated to breakdown issues in high-gradients, including various modeling and possible triggers that starts a RF vacuum breakdown. SLAC group presented an enormous amount of observational data on various conditions where breakdown occurs. The afternoon session also included presentation on computational model (there it is again!) that tries to track or describe multipactor in an RF field.

By the end of the session, I was pooped!


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