Like all others proton linear accelerators at hundreds of MeV and more, the linac is composed of a sequence of 3 segments:

Injector, Medium energy accelerator, High energy accelerator

System Description

The TOP IMPLART injector, is a 7 MeV accelerator composed of a duoplasmatron proton source followed by a 3 MeV RFQ and a 4 MeV DTL, both RFQ and DTL operaing at 425 MHz. The medium energy accelerator is composed of a number of 3 GHz SCDTL accelerating modules that bring the energy up to 71 MeV. The High energy part is composed of a number of 3 GHz CCL modules accelerating he beam up to the desired energy between 100 and 230 MeV. Differently from other machines the injector do not operate at a subharmonic of the main SCDTL and CCL frequency. This was a choice that simplifies the RF plant although causing large losses between the injected beam and the accelerated beam from the first SCDTL module. But this is not a radioprotection  issue, since the beam current is very low as required by the application, and since most losses are found in the first two SCDTL modules (below 18 MeV) after which all particles are accelerated by all structures thereafter.

The main difference to existing linacs is the amount of current delivered by the device. Unless the others that are used for very high current applications like neutron or radioisotope production, here the current is so low, for protontherapy application, that is possible to operate with small bore holes and therefore at at high RF frequency (3 GHz, small bore hole) also in medium and high energy structures

 

In general the system will have the following characteristics:

INJECTOR: Energy, 7 MeV , pulse current 10-200 uA, duration 80-20 us, repetition rate 10-100 Hz

SCDTL: Energy 71 MeV, pulse current 1-10 uA, duration 4 us, repetition rate 10-100 Hz

CCL: Energy 71—150 MeV, pulse current 1-10 uA, duration 4 us, repetition rate 10-100 Hz

The CCL energy will be varied (it is possible only above 85 MeV) by varying the power fed into the last powered acceleration module (see CCL page)

SUBSYSTEMS

INJECTOR     LEBT     SCDTL     CCL      RF SYSTEM      DIAGNOSTICS      DOSIMETRY    CONTROL SYSTEM   RADIOPROTECTION

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