| 摘要 |
A device for furnishing a scanning beam intended for irradiating a target, the irradiating dose level having a predetermined distribution on the target. The device comprises a main magnetic system having a plurality of polepieces for scanning the charged particle 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 quadripoles with respective 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.
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