Transformation of the Beam Intensity Distribution and Formation of a Uniform Ion Beam by Means of Nonlinear Focusing

Abstract

Avoiding undesirable thermal stress or damage of a target vessel is an essential subject in high-intensity beam irradiation for accelerator-driven neutron production. A promising method to tailor the transverse beam intensity distribution for uniform beam irradiation on the target is the use of multipole magnets. We, therefore, study the transformation and uniformization of the transverse intensity distribution by means of nonlinear focusing induced from multipole magnets. It is theoretically described how the intensity distribution is transformed and made uniform by the nonlinear focusing force. Large-area uniform proton and heavy-ion beams are experimentally formed using octupole magnets at the azimuthally-varying-field cyclotron in Japan Atomic Energy Agency.

Effects of Beam Conditions in Ground Irradiation Tests on Degradation of Photovoltaic Characteristics of Space Solar Cells

“…In the case of the defocus beam of 10 MeV proton, a primary beam with a Gaussian distribution over a diameter of~80 mm was uniformized using multipole magnets to form a rectangular exposure area up to 80 mm × 100 mm. This unique technique was developed at QST Takasaki [6][7][8]. 1.0 × 10 9 cm −2 s −1 (Φ ≤ 1.0 × 10 12 cm −2 ), 5.0 × 10 9 cm −2 s −1 (1.0 × 10 12 < Φ < 2.0 × 10 13 cm −2 ), 1.0 × 10 10 cm −2 s −1 (Φ ≥ 2.0 × 10 13 cm −2 ) 8.8 × 10 10 cm −2 s −1 Institute QST Takasaki For the 10 MeV proton experiment, proton irradiation and LIV measurements were alternately implemented in an irradiation chamber.…”