Are Adiabatic Invariants Violated for 10 keV Electrons During a Substorm?

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SUMMARY

The discussion focuses on the violation of adiabatic invariants for 10 keV electrons during a substorm, particularly when the magnetic field at L = 6.5 changes over a period of less than 40 minutes. The condition for non-violation is established as the ratio of disturbance time to invariant time being significantly greater than 10. Key equations involved include the Bounce Period, Drift Period, and Gyro Period, which are essential for analyzing the behavior of electrons under varying magnetic conditions.

PREREQUISITES
  • Understanding of adiabatic invariants in plasma physics
  • Familiarity with magnetic field dynamics in geostationary orbits
  • Knowledge of the Bounce, Drift, and Gyro Period equations
  • Basic concepts of electron behavior in electromagnetic fields
NEXT STEPS
  • Calculate the Bounce Period for 10 keV electrons using the provided formula
  • Analyze the impact of varying the angle αeq on the Drift Period
  • Explore the implications of adiabatic invariants in different magnetic field configurations
  • Research the effects of substorm dynamics on electron trajectories in space physics
USEFUL FOR

Students and researchers in plasma physics, astrophysics, and space weather, particularly those studying the behavior of charged particles in varying magnetic fields.

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Homework Statement


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 ##

Homework 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}##

The Attempt at a Solution


Not sure what value of ##\alpha_{eq}## to use?
 
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What are the two extremes for the periods of interest (ie when the sin term is +1 or -1)?
 

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