A proton of kinetic energy moves (nearly) perpendicular to the field on the Earth's…
PHYSICS · Multi-part · Fermi University Physics · Plasma Physics · The plasma state and single-particle motion · Laboratory, industrial and space plasmas
Plasma Physics, Ch One particle in given fields: gyration and the guiding-centre drifts
Problem
A proton of kinetic energy 300keV moves (nearly) perpendicular to the field on the Earth's L=5 dipole shell, at equatorial distance r=5RE from the centre, where RE=6371km. On a dipole shell labelled L the equatorial field strength is B=B0/L3 with B0=3.12×10−5T, and the field-scale length is LB=r/3.
((a)) Find the equatorial field B on this shell and the proton's Larmor radius rL.
((b)) Find LB and the ratio ϵ=rL/LB.
((c)) State, giving the reason, whether the guiding-centre ordering is satisfied for this proton.