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
Electron-beam welding source of electrons for electron-beam welders, the material must fulfill certain requirements: These and other conditions limit the choice of material for the emitter to metals with high melting points, practically to only two: tantalum and tungsten. With tungsten cathodes, emission current densities about 100 mA/mm can be achieved, but only a small portion of the emitted electrons takes part in beam formation, depending on the electric field produced by the anode and control electrode voltages. The type of cathode most frequently used in electron-beam welders is made of a tungsten strip, about 0.05 mm thick, shaped as shown in