Design, manufacturing and tests of the LIPAc high energy beam transport line

Abstract

The International Fusion Materials Irradiation Facility (IFMIF) is a projected accelerator-based, D-Li neutron source for fusion reactor materials qualification. LIPAc (Linear IFMIF Prototype Accelerator) is an accelerator aiming to generate a 125 mA, 9 MeV continuous wave deuteron beam, which is currently being commissioned in Rokkasho (Japan) with the objective of validating the IFMIF accelerator design. In LIPAc, a 10 m long High Energy Beam Transport line (HEBT) will connect the exit of the superconducting linac to the beam dump (BD). The HEBT line must accommodate the diagnostics for beam characterization and open the beam at the end to allow its stopping at the BD. The line contains several magnets to control the beam shape and its trajectory, maintaining beam losses below 1 W m−1 along the beamline to limit activation of surrounding elements and allow hands-on maintenance. In this work, the LIPAc HEBT line project is described since its origins. A summary of the beam dynamics calculations and other studies (vacuum, radioprotection, assembly, alignment) that led to the conceptual design of the line is done. After that, the detailed design of the line is presented, justifying the main design decisions taken and finally, the manufacturing and procurement process and the acceptance tests performed are summarized.

Beam physics design of a 30-MW beam transport to the target for an accelerator-driven subcritical system

“…Table 3 presents the different element errors for the static and dynamic cases. The amplitudes are based on the error tolerance studies of the JAEA-ADS linac [2] and other high-intensity beam transport lines [13,14]. As depicted in table 4, for the input beam error, the amplitude for the static cases employed the results of the fast recovery compensation studies for the JAEA-ADS linac, which are rematched schemes to enable a quick-stable linac operation recovery with an acceptable beam quality in case of failures in the superconducting radiofrequency cavities or magnets.…”

Design and manufacturing of the combined quadrupole and corrector magnets for the LIPAc accelerator high energy beam transport line

“…TraceWin code [9] has been considered as the reference code in the LIPAc project, as it includes 2D and 3D space charge models, the capability of modeling the different accelerator elements either using analytical expressions or field maps, a correction procedure based on diagnostics as well as an automatic procedure to analyze static and dynamic errors for all the Linac elements using several computers based on a client/server architecture. The nominal quadrupole gradients were obtained after performing extensive beam dynamics calculations to optimize the beam transport along the HEBT line fulfilling the line requirements [6]. Positive values mean that the magnet focuses the beam in the horizontal plane and defocuses the beam in the vertical plane.…”

“…internal radii were chosen after a large number of simulations considering possible errors, and giving large margins, to assure that the number of beam particles hitting the beam pipe is kept under the established limits for the HEBT design [6]. The magnet aperture radii (r A ) were defined by adding 1.5 mm to the pipe internal radius to account for the pipe thickness, and an additional margin of 1.5 mm to allow for manufacturing and assembly tolerances of the components.…”

“…Allowable tolerances in the quadrupole fields and in the magnets positioning were obtained from statistical beam dynamics simulations [6,8]. The analysis was done using several hundreds of combinations of errors in the magnets with random amplitudes.…”

“…The high energy beam transport (HEBT) line [6] connects the exit of the SRF Linac down to the entrance of the beam dump [7] where the beam is stopped. The HEBT line has been designed to transport correctly the high power beam, minimizing the beam losses and adapting the beam parameters at the beam dump entrance to those required for a correct stopping.…”