  Synchrotron radio emission from non-relativistic jets powered by massive
protostars has been reported, indicating the presence of relativistic electrons
and magnetic fields of strength ~0.3-5 mG. We study diffusive shock
acceleration and magnetic field amplification in protostellar jets with speeds
between 300 and 1500 km/s. We show that the magnetic field in the synchrotron
emitter can be amplified by the non-resonant hybrid (Bell) instability excited
by the cosmic-ray streaming. By combining the synchrotron data with basic
theory of Bell instability we estimate the magnetic field in the synchrotron
emitter and the maximum energy of protons. Protons can achieve maximum energies
in the range 0.04-0.65 TeV and emit gamma rays in their interaction with matter
fields. We predict detectable levels of gamma rays in IRAS 16547-5247 and IRAS
16848-4603. The gamma ray flux can be significantly enhanced by the gas mixing
due to Rayleigh-Taylor instability. The detection of this radiation by the
Fermi satellite in the GeV domain and the forthcoming Cherenkov Telescope Array
at higher energies may open a new window to study the formation of massive
stars, as well as diffusive acceleration and magnetic field amplification in
shocks with velocities of about 1000 km/s.

High Energy Astrophysical Phenomena