Fluctuations of the azimuthal and radial magnetic field in the startup plas
ma of the end system of the AMBAL-M tandem mirror system are measured by ma
gnetic probes. An analysis of the spectra and radial profiles of the magnet
ic-field and density fluctuations shows that there is a correlation between
these quantities, which can be explained in terms of the Kelvin-Helmholtz
instability in a plasma stream flowing out of the gas-discharge source. The
characteristic parameters of the stream inhomogeneities are estimated. The
radial profile of the particle flux is determined from simultaneous measur
ements of the plasma density and radial magnetic field. The diffusion coeff
icient related to magnetic-field fluctuations is estimated.