Abstract: A beam current control device in a technical corpuscular beam apparatus for welding, cutting, boring, melting, hardening and like operations, wherein a corpuscular beam emitted by a beam gun is switched between an active position in which it impinges on the work-piece and a rest position in which at least its major portion does not impinge on the work-piece, comprises means for measuring the gun emission current, means for measuring the beam current impinging on the work-piece when the beam is switched from said rest into said active position, means for forming a quotient signal corresponding to the quotient of said emission current and said beam current, means for producing a reference signal, means for deriving an error signal from said quotient and reference signals, and control means responsive to said error signal to control said emission current in a sense to minimize said error signal.