Cosmic-ray fluctuations and interplanetary magnetic fields

The relations of cosmic-ray fluctuations to those of interplanetary magnetic fields (IMF) and the possible consequences of the magnetic helicity of IMF for the acceleration of cosmic rays are examined using experimental data from two neutron monitors and data on IMF in interplanetary space.The spectral tensor of IMF at two different distances from the Sun is determined for several selected intervals of 10–15 hours duration. Data from IMP-8 and Helios-1 are used. Cross correlations of IMF with cosmic rays measured by the Lomnický tít neutron monitor, based on 5 min data, are estimated. A comparison of spectral slopes of the power spectrum density at the Lomnický tít and Calgary neutron monitors demonstrates the possibility of using a single neutron monitor data point as a representative of the CR fluctuation power spectrum slope. It is shown that the data are not in all cases consistent with model of 3D turbulence in interplanetary space as the cause of the cosmic-ray fluctuation spectrum. Magnetic helicity, kinetic fluctuation energy, and the correlation length of the magnetic field are deduced from the limited amount of data and compared with values obtained by Matthaeus and Goldstein (1982). Based on the theoretical approach by Fedorovet al. (1992) the efficiency of acceleration of cosmic rays due to the presence of anisotropic reflective non-invariant IMF at various heliospheric distances is estimated.