We study several effects that influence the strength of the proton cyclotron and atomic features in the thermal spectra of magnetic neutron stars. We show that it is possible for vacuum polarization to strongly suppress the spectral lines when the magnetic field B & 10 G. For weaker fields (B . 7× 10 G), the surface spectrum is unaffected by vacuum polarization; thus the proton cyclotron absorp...

We have measured the picosecond time-resolved cyclotron resonance of photogenerated transient carriers in undoped InSb/Al0.09In0.91Sb quantum wells by two-color pump-probe spectroscopy in a magnetic field. The strong conduction-band nonparabolicity of InSb causes the average cyclotron mass of the electrons, which we monitor directly in time, to decrease as the electrons relax towards the band e...

A cyclotron-resonance maser (CRM) is implemented in a periodic quadrupole waveguide. The device oscillates at the fundamental and high harmonics of the cyclotron frequency. This CRM employs a tenuous low-energy electron beam ( approximately 10 keV, 0.2 A). The periodic structure consists of an array of disks along the quadrupole transmission line, hence it combines both azimuthal and axial peri...