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!

Why don't we put particle accelerators in a Jet?

  1. Jun 18, 2014 #1
    the velocity of the jet will add to the velocity of the particles , so they will be have greater velocity right?
  2. jcsd
  3. Jun 18, 2014 #2
    But then the thing we are colliding them with would also be on a jet...

    Besides, how could you fit a particle accelerator on a jet? And, have you calculated what % increase in velocity doing all this would net you? The particles are going very fast. Jet speed is virtually nothing compared to them. Might as well put a gun on a snail to increase the bullet's velocity.
  4. Jun 18, 2014 #3
    lol makes sense now , i though i had a genius idea
  5. Jun 18, 2014 #4


    User Avatar

    Staff: Mentor

    The speed of a jet aircraft (less than one km/sec) isn't even a rounding error compared with the speed of particles in an accelerator (300,000 km/sec). It would make more sense to increase the effectiveness of an anti-tank gun by mounting it on the back of a tortoise.
  6. Jun 18, 2014 #5


    User Avatar

    Staff: Mentor

    The LHC main tunnel is 17 miles in circumference and the helium-4 cooling its magnets weighs 96 tons alone. The magnets themselves weigh over 43,000 tons. I'd like to see that thing fly.
  7. Jun 18, 2014 #6
    The secret is we must create very fast and powerful jet planes. Good luck!
  8. Jun 18, 2014 #7


    User Avatar

    Staff: Mentor

    Velocities don't add linearly at high speed like they do at low speed. So even if you could put a particle accelerator on a plane, it wouldn't accomplish anything.
  9. Jun 23, 2014 #8
    I think OP was not talking about a collider (going in circles and ending in a cancelling collision) but rather an open ended one so the great velocity of the particles would be a reaction engine.

    I think this analogy is backwards in that the Jet is the Snail and the Bullet is The Particles. Attaching a gun to a snail and firing it most likely would accelerate the snail! :biggrin: The great difference is that the bullet has substantial mass relative to the snail. In the case of the Jet, the particles have many orders of magnitude lower mass than the Jet - ineffective in a planet's gravity and atmosphere.

    However, once in Open Space, this changes. While the link is not exactly a particle accelerator on the scale of LHC, it is instructive. Here - http://www.nasa.gov/centers/glenn/about/fs21grc.html. These so-called Ion Engines can attain astounding end speeds (probably what fueled OPs idea) but the acceleration is slow to build due to the low mass of the ejecta. They require no counter-acting forces and great distances within which to build up to the speed of the ejecting ions.

    Thus an Ion Engine propelled rocket can not launch from the ground. It would just sit on the pad. Some other form of power is required to achieve escape velocity against the mighty pull of Earth's gravity. Assuming there could be a reasonable power source for using a typical particle accelerator used for colliding experiments in an open-ended fashion, it could potentially achieve very high speeds, given enough room to build it up, and enough fuel to continually power it versus the added mass of the power source and it's fuel.

    Back to the Snail and the Gun, like most chemical engines, the gun has explosive power - very substantial pressure and mass released in a sudden burst. This creates rapid acceleration for a short term but very low velocities relative to accelerators. Our chemical rockets behave much like this with the exception of not throwing some great mass, depending totally on a sustained reaction.

    If you notice that the acceleration from the gun behaves on the snail almost instantaneously, while a chemical rocket lifts very slowly at first from the pad, gathering speed over time, and then continue in that direction at some far "distance down the line" we come to particle acceleration engines and you can see how these would be impractical on planet bound Jets traveling very short distances against great forces.
    Last edited: Jun 23, 2014
  10. Jun 23, 2014 #9
    And attaching it to a person would accelerate the person too (and whatever that person manages to stay attached too). You cant get around newton's laws here. If the bullet is going to change momentum that which pushes on it must change momentum. But on a moving object, snail or otherwise, the bullet will have a velocity before being fired that will result is a slightly faster initial velocity with respect to the ground.
    Last edited: Jun 23, 2014
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook