Measurements of the Mass Density Dependence Along Field Lines Using Toroidal Alfven Frequencies Observed by the CRRES Spacecraft

It is sometimes possible to measure several harmonics of the toroidal Alfven wave for a particular field line. Because of the difference in parallel structure for these harmonics, they react differently to density at different points along a field line. Using this fact, it is possible to use the frequencies to remotely sense the mass density at different points along a field line. Here we examine some new techniques for calculating the mass density based on the toroidal frequencies. Using toroidal harmonics measured by the magnetic field instrument on the CRRES spacecraft, we compare the inferred mass density at the spacecraft location to the electron density measured locally using plasma wave data.