[en] The nuclear reaction ³H(d, n) ⁴He has a cross-section maximum at about 100 keV deuteron energy. This has prompted the development and construction of low voltage ion accelerators (a few 100 kV) with high current ion sources (up to 1 A), as well as the development of a special target technology. As a result it is possible at present to build neutron generators with source strengths of up to 10¹⁴ s-¹. A distinction is drawn between pumped neutron machines with a vacuum system, and generators with sealed tubes. This paper describes the individual components of these generator types, compares possible variants and presents yields and other data. The advantages and particular features of neutron generators with sealed tubes are discussed. The necessity of shielding neutron sources is stressed. (orig.)