| 摘要 |
<p>IMPROVEMENTS IN OR RELATING TO A DEVICE FOR SCANNING A TARGET WITH A BEAM OF CHARGED PARTICLES. A device for furnishing a scanning beam intended for irradiating a target in such a manner that the irradiating dose level has a predetermined distribution on the target. The device comprises a main magnetic system having a plurality of polepieces for scanning the beam and a secondary magnetic system having a plurality of polepieces and being located upstream of the main magnetic system for variably offsetting the beam entering the main magnetic system. In a preferred embodiment, the main and secondary magnetic systems are provided with four-poles associated with coils which are supplied in pairs with signals SX1, SY1, and SX2, SY2, the signals SX1, SY1 being for example of "sawtooth" waveform and those SX2, SY2 of "squarewave" waveform. The signals may be co-phasal or in phase-opposition.</p> |
