Neutron star radiation from pulsars is thought to be primarily emitted from regions near their magnetic poles. If the magnetic poles do not coincide with the rotational axis of the neutron star, the emission beam will sweep the sky, and when seen from a distance, if the observer is somewhere in the path of the beam, it will appear as pulses of radiation coming from a fixed point in space (the so-called "lighthouse effect"). The fastest-spinning neutron star known is PSR J1748-2446ad, rotating at a rate of 716 times a second or 43,000 revolutions per minute, giving a linear speed at the
Beam dump beams to be absorbed can run into the megajoules. Materials used for such beam dumps include blocks of copper, aluminium, carbon, beryllium, and tungsten. The block often has a long conical hole, where the beam hits it, so as to spread the heating over a larger region of the block. If the beam to be absorbed is high-powered, these blocks may be up to several meters long and water-cooled. Pools of mercury have also been used. If the particles in the beam are energetic enough, induced radioactivity, production of neutrons by spalling, radiation embrittlement, and production of secondary particles can