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!

Violation of Adiabatic Invariances

  1. Feb 10, 2016 #1
    1. The problem statement, all variables and given/known data
    Consider the following disturbances. Clearly state for 10 keV electrons if any of the three adiabatic invariants violated, and justify your answer?
    (i) The magnetic field at L = 6.5 (~geo-stationary orbit) steadily changes strength and direction from one state to another in a time of less than 40 minutes during a substorm.
    Hint: the condition for non-violation is that ##\tau_{ disturbance} / \tau_{ invariant} >>1 ##
    It is useful to quantify “>>” : for this problem sheet please express the condition as
    ##\tau_{ disturbance} / \tau_{ invariant} >>10 ##

    2. Relevant equations
    Bounce Period ## = L R_{E} (\frac{W}{M})^{-0.5}(3.7 -1.6 sin(\alpha_{eq}))##
    Drift Period ## = \frac{{2}q B_E R_E ^2}{3LW}\frac{1}{0.7+0.3sin\alpha_{eq}}##
    Gyro Period ## = \frac{qB}{m}##

    3. The attempt at a solution
    Not sure what value of ##\alpha_{eq}## to use?
  2. jcsd
  3. Feb 12, 2016 #2


    User Avatar
    Science Advisor
    Gold Member

    What are the two extremes for the periods of interest (ie when the sin term is +1 or -1)?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted

Similar Discussions: Violation of Adiabatic Invariances
  1. Adiabatic expansion (Replies: 4)

  2. Adiabatic expansion (Replies: 5)

  3. Adiabatic expansion (Replies: 3)

  4. Adiabatic Process (Replies: 1)