The present invention relates to a circular particle accelerator capable of modulating the particle beam current exiting the circular particle accelerator. The circular particle accelerator includes: an ion source for generating the particle beam; Dee electrode and counter-Dee electrode separated from each other by gaps for accelerating the particle beam, the counter-Dee electrode being grounded; a generator capable of applying an alternating high voltage to the Dee electrode, so as it is possible to have an electric field between the gaps; means for measuring the current intensity of the particle beam exiting the circular particle accelerator. It also comprises a regulator capable of modulating the Dee electrodes voltage amplitude (VD) by comparing a given set point (I0) of the current intensity of the particle beam and the measured value of the current intensity (I′M) of the particle beam.