Longitudinal Beam Dynamics for the Heavy-Ion Synchrotron Booster Ring at HIAF

To accelerate high-intensity heavy-ion beams to high energy in the booster ring (BRing) at the High-Intensity Heavy-Ion Accelerator Facility (HIAF) project, we take the typical reference particle 238U35+, which can be accelerated from an injection energy of 17 MeV/u to the maximal extraction energy of 830 MeV/u, as an example to study the basic processes of longitudinal beam dynamics, including beam capture, acceleration, and bunch merging. The voltage amplitude, the synchronous phase, and the frequency program of the RF system during the operational cycle were given, and the beam properties such as bunch length, momentum spread, longitudinal beam emittance, and beam loss were derived, firstly. Then, the beam properties under different voltage amplitude and synchronous phase errors were also studied, and the results were compared with the cases without any errors. Next, the beam properties with the injection energy fluctuation were also studied. The tolerances of the RF errors and injection energy fluctuation were dictated based on the CISP simulations. Finally, the effect of space charge at the low injection energy with different beam intensities on longitudinal emittance and beam loss was evaluated.

Investigation of high current electron beam dynamics in linear induction accelerator for creation of a high-power THz radiation source

The work addresses the use of electron beam produced by the linear induction accelerator to generate terahertz radiation pulses of 100 MW power level based on a free electron laser scheme. The beam parameters required for efficient generation are given. The features of transverse beam dynamics when transporting the beam through the linac are investigated. Emphasis is put on the electron injector which geometry and operation parameters mainly determine the beam characteristics at the linac exit. Most of the possible factors contributing to the beam emittance gain in the accelerator are considered. The obtained analytical estimates are compared to the numerical simulation results. The experimental results on compressing and transporting the beam having the electron energy of 5 MeV and the current of 1 kA in the transport system of free electron laser are presented.

Physics design of the CiADS MEBT

The superconducting linac for China initiative Accelerator Driven Subcritical System (CiADS) is the world-leading ADS-driver under construction with state-of-the-art technologies. This system is designed to accelerate a 5 mA proton beam to 500 MeV energy, and then delivering 2.5 MW of beam power to the neutron production target. The Middle Energy Beam Transport (MEBT) is designed with great emphasis on smoothing matching between the upstream and downstream acceleration sections, beam diagnostics layout and beam quality control. It is proposed and successfully implemented to immigrate the phase space distortion and reduce the increase of beam emittance. The acceptance of MEBT is optimized to make all the particles inside the effective acceptance of the superconducting section even with machine errors. This pertinent design of MEBT is suitable for the high-power superconducting accelerator of CiADS.

High energy implementation of coil-target scheme for guided re-acceleration of laser-driven protons

Developing compact ion accelerators using intense lasers is a very active area of research, motivated by a strong applicative potential in science, industry and healthcare. However, proposed applications in medical therapy, as well as in nuclear and particle physics demand a strict control of ion energy, as well as of the angular and spectral distribution of ion beam, beyond the intrinsic limitations of the several acceleration mechanisms explored so far. Here we report on the production of highly collimated ($$\sim 0.2^{\circ }$$ ∼ 0 . 2 ∘ half angle divergence), high-charge (10s of pC) and quasi-monoenergetic proton beams up to $$\sim$$ ∼ 50 MeV, using a recently developed method based on helical coil targetry. In this concept, ions accelerated from a laser-irradiated foil are post-accelerated and conditioned in a helical structure positioned at the rear of the foil. The pencil beam of protons was produced by guided post-acceleration at a rate of $$\sim$$ ∼ 2 GeV/m, without sacrificing the excellent beam emittance of the laser-driven proton beams. 3D particle tracing simulations indicate the possibility of sustaining high acceleration gradients over extended helical coil lengths, thus maximising the gain from such miniature accelerating modules.

Оптимизация масс-сепараторов

The optimization of separator masses in this paper is based on the realization of the linearity of the system under study and the consequences of Liouville's theorem. The properties of several mass separators with an ion energy of 30 keV and a beam emittance of 4 mm*mrad are considered. Focusing is provided by an aberration-free lens and a magnetic corrector. Phase diagrams along the beam path are in the form of parallelograms, which indicates the absence of geometric aberrations. For each of the separators, the resolution calculated in the linear approximation coincides with the simulation results. It is shown that a mass separator based on a magnet with a rotation angle of 54.70 has a resolution of about 5000, and a separator based on two magnets with a rotation angle of 450 and 900, respectively, has a resolution of 14000-15000.