Neutron star between 10 and 10 (100 million to 1 quadrillion) times as strong as that of the Earth. The gravitational field at the neutron star's surface is about (200 billion) times that of the Earth. As the star's core collapses, its rotation rate increases as a result of conservation of angular momentum, hence newly formed neutron stars rotate at up to several hundred times per second. Some neutron stars emit beams of electromagnetic radiation that make them detectable as pulsars. Indeed, the discovery of pulsars by Jocelyn Bell Burnell in 1967 was the first observational suggestion that neutron stars exist. The
Electron-beam lithography cold emission sources, in spite of the former's slightly larger beam size, because they offer better stability over typical writing times of several hours. Both electrostatic and magnetic lenses may be used. However, electrostatic lenses have more aberrations and so are not used for fine focusing. There is no current mechanism to make achromatic electron beam lenses, so extremely narrow dispersions of the electron beam energy are needed for finest focusing. Typically, for very small beam deflections electrostatic deflection "lenses" are used, larger beam deflections require electromagnetic scanning. Because of the inaccuracy and because of the finite number of steps