Cyclotron

• US 7,446,490 B2
• Filed: 11/14/2003
• Issued: 11/04/2008
• Est. Priority Date: 11/25/2002
• Status: Expired due to Fees

• Current Assignee: Ion Beam Applications s.a.
• Original Assignee: ION BEAM Appliances SA
• Inventors: Genin, Frédéric, Jongen, Yves
• Primary Examiner(s): Berman; Jack I.
• Assistant Examiner(s): Smyth; Andrew
• Application Number:
  US10/536,333
• Publication Number:
  US 20060255285A1
• Time in Patent Office: 1,817 Days
• Field of Search: 250/251, 315/502
• US Class Current: 315/502
• CPC Class Codes: H05H 13/00 Magnetic resonance accelerators; Cyclotrons strophotrons, turbine tubes H01J25/62
• CPC Class Codes: H05H 7/10 Arrangements for ejecting particles from orbits

Abstract

The invention relates to a cyclotron which can produce a beam of accelerated charged particles that are intended for the irradiation of at least one target (200). The inventive cyclotron consists of a magnetic circuit which essentially comprises: an electromagnet with at least two poles (1, 1′), namely an upper pole (1) and a lower pole (1′), which are disposed symmetrically in relation to a mid-plane (110) which is perpendicular to the central axis (100) of the cyclotron and which are separated by a gap (120) containing the circulating charged particles and return flux (2) in order to close the aforementioned magnetic circuit; and a pair of main induction coils (5, 5′) which are used to create an essentially-constant main induction field in the gap between poles 1 and 1′. The invention is characterised in that it comprises means of centring the above-mentioned beam, consisting of at least one pair of bucking coils (6, 7) which are supplied by an electrical source (8) and which can modulate the intensity of the main induction field produced by the main coils (5, 5′), in order to increase the intensity of the induction field in a first area of the cyclotron and to reduce the intensity of the induction field in a second area of the cyclotron, which is diametrically opposed to the central axis (100) of the cyclotron.

Claims

1. A cyclotron capable of producing a beam of accelerated charged particles intended for the irradiation of at least one target, said cyclotron comprising a magnetic circuit that is essentially comprised of:

an electromagnet with at least two poles, an upper pole and a lower pole, said poles being disposed symmetrically with relation to a median plane that is perpendicular to the central axis of the cyclotron, and separated by a gap where charged particles and flux returns circulate to close said magnetic circuit;

a pair of main induction coils for creating an essentially constant main induction field in the gap, between said poles, characterized in that it comprises means for centering said beam comprising at least one pair of bucking coils powered by a power supply and capable of modulating the intensity of the main induction field by said main coils in order to obtain an increase in the intensity of the induction field in a first area of the cyclotron and a reduction in intensity of the induction field in a second area of the cyclotron that is diametrically opposed with relation to the central axis of the cyclotron.

2. The cyclotron according to claim 1, wherein the bucking coils surround portions of the flux return disposed in diametric opposition with relation to the central axis of the cyclotron.

3. A method for centering a beam extracted from a cyclotron on a target, the method comprising:

providing a cyclotron comprising a magnetic circuit essentially comprised of an electromagnet with at least two, an upper pole and a lower pole, said poles being symmetrically disposed with relation to a median plane that is perpendicular to the central axis of the cyclotron and separated by a gap where the charged particles and flux returns circulate to close said magnetic circuit;

a pair of man induction coils for creating an essentially constant main induction field in the gap between said poles wherein;

the cyclotron is equipped with at least one pair of bucking coils disposed in such a way as to surround the diametrically opposed portions of the flux return with relation to the central axis of the cyclotron;

powering the pair of main coils in such a way as to create an essentially constant magnetic field in the gap of the cyclotron, and

powering the bucking coils through a power supply in such a way as to increase the intensity of the induction field in a first area of the cyclotron and to reduce the intensity of the induction field in a second area situated in diametric opposition with relation to the central axis of the cyclotron.

4. The method according to claim 3, wherein the intensity of the current of the power supply is regulated or adjusted in order to maximize the intensity of the beam hitting a target.

5. The method according to claim 4, wherein:

the intensity of the current of the beam is measured at said target by using a detector,

this measurement is transmitted to a regulator, and according to this measurement, the intensity of the current in the bucking coils is regulated or adjusted through an adjustment in the supply current.