  In this study we investigate jet interaction at a microscopic level in a
cosmological environment, which responds to a key open question in the study of
relativistic jets. Using small simulation systems during prior research, we
initially studied the evolution of both electron-proton and electron-positron
relativistic jets containing helical magnetic fields, by focusing on their
interactions with an ambient plasma. Here, using larger jet radii, we have
performed simulations of global jets containing helical magnetic fields in
order to examine how helical magnetic fields affect kinetic instabilities such
as the Weibel instability, the kinetic Kelvin-Helmholtz instability (kKHI) and
the Mushroom instability (MI). We found that the evolution of global jets
strongly depends on the size of the jet radius. For example, phase bunching of
jet electrons, in particular in the electron-proton jet, is mixed with larger
jet radius due to the more complicated structures of magnetic fields with
excited kinetic instabilities. In our simulation study these kinetic
instabilities lead to new types of instabilities in global jets. In the
electron-proton jet simulation a modified recollimation occurs and jet
electrons are strongly perturbed. In the electron-positron jet simulation mixed
kinetic instabilities occur at early times followed by a turbulence-like
structure. Simulations using much larger (and longer) systems are further
required in order to thoroughly investigate the evolution of global jets
containing helical magnetic fields.
