Electron acceleration hyperfrequency device comprising: - an electron gun which supplies an electron beam along an axis ZZ', - a hyperfrequency structure for accelerating the electrons of the beam supplied by the electron gun, the hyperfrequency structure having, along the axis ZZ', two opposing ends (62, 64), one of the ends at the side of the electron gun comprising an input of the electron beam, the other end comprising an output of the accelerated electrons of the beam, between the two ends of the hyperfrequency structure, a series of n coupled cavities C1, C2,... Ci,... Cx,... Cn, along the axis ZZ', having a central resonance frequency f0, x being the rank of the cavity in the series of n cavities, the first cavity C1 of the series of n cavities being at the side of the end at the side of the electron gun, the hyperfrequency structure further having an input of the hyperfrequency excitation signal Urf via an input cavity Ci which is part of the series of n cavities, - a radiofrequency generator which can be controlled in terms of frequency Fv and which comprises a frequency control input, a hyperfrequency output which supplies the hyperfrequency excitation signal Urf at the frequency Fv at the input of the hyperfrequency signal of the hyperfrequency structure, - a central unit UC which supplies a signal for controlling the frequency Fv at the frequency control input of the radiofrequency generator, the central unit UC being configured to control at least the frequency Fv of the radiofrequency generator around the central resonance frequency f0 in order to supply at the output of the hyperfrequency structure a series of pulses 11, 12, l3,....ly,.... of accelerated electrons having levels of energy E1, E2, E3,... Ey,... which can vary from one pulse ly to the following pulse l(y+1), respectively, y being the rank of the pulse in the series of pulses, a frequency Fvy of the excitation signal Urf during a pulse ly producing an energy Ey of the accelerated electrons at the output of the hyperfrequency structure, characterised in that the input cavity is a cavity close to the end of the hyperfrequency structure at the side of the electron gun and is selected from the first cavity C1, that is, x = 1, and a cavity Ci in the order of x=n/3. - an electron gun which supplies an electron beam along an axis ZZ', - a hyperfrequency structure for accelerating the electrons of the beam supplied by the electron gun, the hyperfrequency structure having, along the axis ZZ', two opposing ends (62, 64), one of the ends at the side of the electron gun comprising an input of the electron beam, the other end comprising an output of the accelerated electrons of the beam, between the two ends of the hyperfrequency structure, a series of n coupled cavities C1, C2,... Ci,... Cx,... Cn, along the axis ZZ', having a central resonance frequency f0, x being the rank of the cavity in the series of n cavities, the first cavity C1 of the series of n cavities being at the side of the end at the side of the electron gun, the hyperfrequency structure further having an input of the hyperfrequency excitation signal Urf via an input cavity Ci which is part of the series of n cavities, - a radiofrequency generator which can be controlled in terms of frequency Fv and which comprises a frequency control input, a hyperfrequency output which supplies the hyperfrequency excitation signal Urf at the frequency Fv at the input of the hyperfrequency signal of the hyperfrequency structure, - a central unit UC which supplies a signal for controlling the frequency Fv at the frequency control input of the radiofrequency generator,