Laboratori Nazionali del Sud

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Research

Aisha

AISHa (Advanced Ion Source for Hadrontheraphy)

 

In order to answer to specific requests of the hadron therapy facilities, the AISHA source has been designed with the aim to provide highly charged ion beams with low ripple, high stability and high reproducibility; key features were also the low maintenance time and the minimization of electrical consumption. Actually most of the non-conventional cancer therapy centers are facilities based on proton beams while an arising interest is shown in the use of heavier ions such as: Carbon, Lithium, Berillium. AISHa is designed to fulfill these new requests together with  the requirements needed for the typical hospital installation (He free, easy to use , etc..) and it represents also a interesting  solution for all the Nuclear Physics facilities based on intense multicharged ion beam production spread all over the world. The construction of AISHA was supported by the incentives in favour of Research Development and Innovation Art.5 Regional law 16/12/2008 - POR FERS Sicilia 2007-2013 (Record#1157 Intervention line 4.1.1.1 Health and life sciences) devoted to small and medium companies integrated with Research Institutions (Partners: HITEC2000 srl, UNICO srl, C3SL) and the funding was allocated to a private-public partnership including INFN.

The AISHa ion source is a hybrid ion source whose magnetic system is based on a permanent magnet hexapole able to reach up to 1.3 T radial field on plasma chamber walls and four superconducting coils for the axial plasma confinement. The main characteristics of the source are summarized in the following table.

AISHa source parameters

 

Radial field (max)

1.3 T

Axial field (INJ/MID/EXTR)

2.7 T / 0.4 T / 1.7 T

Operating frequencies

18 GHz (TFH)

Operating power (max)

1.5 kW + 1.5 kW

Extraction voltage (max)

40 kV

Chamber diameter

=92mm

LHe

Free

The axial magnetic field confinement has been designed on the basis of the previous experience, in particular to minimize the hot electron component and to optimize the ECR heating process by controlling the field gradient at injection and extraction and the resonance length. For the AISHa source it has been decided to adopt a solution employing four coils which permits to have a good control on the above cited parameters. The hexapole has been deeply studied and designed with the OPERA 3D code. During the design the efforts have been focused to analyze and minimize the permanent magnet demagnetization. In fact, due to the presence of high values of Hx and Hy generated by the SC coils a local demagnetization of part of the hexapole assembly may happen.

The magnetic system measurement confirmed the effectiveness of the solutions adopted, the source is actually under commissioning at the INFN-LNS site.

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