1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Concepts behind particle accelerators

  1. Nov 28, 2011 #1
    I'm wondering about linear particle accelerators. THey're something I've been researching for a while, and I found two conflicting ideas. On one source, it states that all you essentially need is a long tube and a high voltage power supply. So, if I had a voltage multiplier and assigned the positive end to one end of the tube, and the negative end from where my electron source is (let's say I'm accelerating electrons), then all I would need is a vacuum chamber and the electrons would accelerate.
    Another source, however, states that you need "drift tubes" and need to apply something like an RF antenna source coupled to your high voltage power source to constantly change the charge on each individual drift tube. I was originally under the impression that one only needed to do this for a cyclotron. Is it necessary to do so for a linac as well?
    And on two other notes:
    a) Is it better for me to study Linacs first, or cyclotrons? I'm thinking Linac would be much easier to study, but...
    b) IF I had a cyclotron, could I simply hook it up to alternate current, or a wall circuit (besides the fact it's dangerous :) ), and let the back and forth flow handle the changing? Or could I get a waveform generator and somehow connect it to my high voltage source, then connect it to the Ds? Would that work?
  2. jcsd
  3. Nov 29, 2011 #2
    Not an expert, as you will understand from my post:

    I probably depends on how much energy you want. You can accelerate charged particles in a very simple way like old-fashioned vacuum tubes and cathode-ray TVs. But the most common method for high energy particles is explained here:


    I expect linear accelerators would be easier to study. Both involve special relativity, but I think that at least for particles with spin the cyclotron is a bit more nontrivial. I'm guessing Thomas-precession would be relevant in that case.

    You need much higher frequencies than your wall voltage. The period must be of the same order as the time it takes the particles to pass through the ring, or through each section of a linear accelerator. This usually means very high frequencies if the particle is to be accelerated up close to the speed of light...
  4. Nov 29, 2011 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    There are DC acceleration, and there are RF acceleration. DC acceleration uses electrostatic E-field to accelerate charged particles, while RF acceleration uses RF fields. The latter tends to have structures that can achieve higher acceleration/speeds. DC fields are limited to the breakdown limit (among other things) of the structure.

    Stan Humphries has an online text on almost everything you need to know to introduce yourself to the principles of particle acceleration.


Share this great discussion with others via Reddit, Google+, Twitter, or Facebook