In this case, Φ in Eq. (201) is the flux encircled by a cyclotron orbit, equal to (−πR2B), where R is its radius given by Eq. (153), and the negative sign accoun...In this case, Φ in Eq. (201) is the flux encircled by a cyclotron orbit, equal to (−πR2B), where R is its radius given by Eq. (153), and the negative sign accounts for the fact that in our case, the “correct” direction of the normal vector n in the definition of flux, Φ=∫B⋅nd2r, is antiparallel to the vector B.
