A method of charging a web or foil is described. The method includes guiding a web or foil having a thickness of 10 [mu]m or larger with at least on roller; providing a linear electron source (100) having a housing (112) acting as an anode, the housing having side walls (312); a slit opening (114) in the housing for trespassing of a linear electron beam, the slit opening defining a length direction of the source; a cathode being arranged within the housing and having a first side (413) facing the slit opening; at least one gas supply (70) for providing a gas into the housing; and a power supply for providing a high voltage between the anode and the cathode; and emitting the linear electron beam, wherein the high voltage is adjusted for providing an electron energy to implant electrons of the electron beam within the web or foil.