This device, in which the deflector comprises deflection coils (2) connected to the output of the control means (3) of their power supply and comprising means (4) of the correction of this power supply in order to adjust the value of the magnetic field produced by the coils (2) as a function of a reference value, is characterized in that the correction means comprise at least one measurement coil (5) of the actual magnetic field produced by the coils of the deflector, which is incorporated in the deflector (1) and whose output is connected to the input of the integration means (6), the output of the integration means (6) being connected to comparison means (7) of the value of the real field to the reference value, the output of an error of these comparison means (7) being connected to the input of amplifying means (9) whose output is connected to the correction means (10) of the current flowing in the coils.
展开▼
