Beam-dynamics Study on Lattice Types in a Low-energy Heavy-ion Superconducting Linear Accelerator

2015 ◽  
Vol 65 (10) ◽  
pp. 976-981
Author(s):  
JangWon KWON ◽  
Eun-San KIM*
Keyword(s):  
Linear Accelerator ◽  
Heavy Ion ◽  
Low Energy ◽  
Beam Dynamics

scholarly journals Beam dynamics design of an energy-variable superconducting heavy ion accelerator

2021 ◽  
Author(s):  
◽  
Malte Alexander Schwarz
Keyword(s):  
Energy Range ◽  
Linear Accelerator ◽  
Drift Tube ◽  
Heavy Ion ◽  
Beam Dynamics ◽  
Heavy Elements ◽  
Output Energy ◽  
Transverse Beam ◽  
High Charge ◽  
Cw Operation

This dissertation describes the development of the beam dynamics design of a novel superconducting linear accelerator. At a main operating frequency of 216.816 MHz, ions with a mass-to-charge ratio of up to 6 can be accelerated at high duty cycles up to CW operation. Intended for construction at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, the focus of the work is on the beam dynamic design of the accelerator section downstream of the high charge injector (HLI) at an injection energy of 1.39 MeV/u. An essential feature of this linear accelerator (Linac) is the use of the EQUUS (Equidistant Multigap Structure) beam dynamics concept for a variably adjustable output energy between 3.5 and 7.3 MeV/u (corresponding to about 12.4 % of the speed of light) with a required low energy spread of maximum 3 keV/u. The GSI Helmholtz Centre for Heavy Ion Research is a large-scale research facility that uses its particle accelerators to perform basic research with ion beams. Research on super-heavy elements ("SHE") is a major focus. It is expected that their production and research will provide answers to a large number of scientific questions. The production and detection of elements with atomic numbers 107 to 112 (Bohrium, Hassium, Meitnerium, Darmstadtium, Röntgenium and Copernicium) was first achieved at GSI between 1981 and 1996. Key to this remarkable progress in SHE research were continuous developments and technical innovations. On the one hand, in the field of experimental sensitivity and detection of the nuclear reaction products and, on the other hand, in the field of accelerator technology. For the acceleration of the projectile beam, the UNILAC (Universal Linear Accelerator), which was put into operation in 1975, has been used at GSI so far. In the course of the reconstruction and expansion of the research infrastructure at GSI, a dedicated new particle accelerator, HELIAC (Helmholtz Linear Accelerator), is now under development to meet the special requirements of the beam parameters for the synthesis of new superheavy elements. Typically, the production rates of super-heavy elements with effective cross sections in the picobarn range are very low. Therefore, a high duty cycle (up to CW operation) is a key feature of HELIAC. Thus, the required beam time for the desired nuclear reactions can be significantly shortened. Theoretical preliminary work by Minaev et al. and newly created knowledge about design, fabrication, and operation of superconducting drift tube cavities have laid the foundation for this work and thus the development of the HELIAC linear accelerator. It consists of a superconducting and a normal conducting part. Acceleration takes place in the superconducting part in four cryomodules, each about 5 m long. These contain three CH cavities, one buncher cavity, two solenoid magnets for transverse beam focusing, and two beam position monitors (BPMs). The following 10 m long normal conducting part is primarily used for beam transport and ends with a buncher cavity. This is operated at a halved frequency of 108.408 MHz. A key feature of this accelerator is the variability of the output energy from 3.5 to 7.3 MeV/u with a small energy uncertainty of ±3 keV/u maximum over the entire output energy range. For the development of HELIAC, the EQUUS beam dynamics concept used combined the advantages of conventional linac designs with the high acceleration gradients of superconducting CH-DTLs. By doubling the frequency (compared to the GSI high charge injector) to 216.816 MHz in the superconducting section and using CH cavities at an acceleration gradient of maximum 7.1 MV/m, an acceleration efficiency with superconducting drift tube structures that is unique in the world is made possible. At the same time, the compact lengths of the CH cavities ensure good handling for both production and operation. EQUUS leads to longitudinal beam stability in all energy ranges of the accelerator with the sliding motion of the synchronous phase within each CH cavity. The rms emittance growth is moderate in all levels. The modular design of the HELIAC with four cryomodules basically allows the Linac to be commissioned starting with the first cryomodule, the so-called Advanced Demonstrator. In the subsequent expansion stage with only the first two cryomodules of HELIAC, the lower limit of the energy range to be provided by HELIAC (3.5 MeV/u) can already be clearly exceeded, so that use in regular beam operation at GSI is already conceivable from here on. By means of error tolerance studies, the stability of the HELIAC beam dynamics design against possible alignment errors of the magnetic focusing elements and accelerator cavities as well as errors of the electric field amplitudes and phases have been investigated, basically confirmed and critical parameters have been determined. An additional steering concept via dipole correction coils at the solenoid magnets allows transverse beam control as well as diagnostics by means of two BPMs per cryomodule. With completion of this work in 2021, the CH1 and CH2 cavities have already been built and are in the final preparation and cold test phase. In parallel, the development of the CH cavities CH3-11 has also been started.

Beam Dynamics for High-Power Superconducting Heavy-Ion Linear Accelerator of RAON

2016 ◽  
Vol 63 (2) ◽  
pp. 992-1000 ◽  
Author(s):  
Ji-Gwang Hwang ◽  
Eun-San Kim ◽  
Hye-Jin Kim ◽  
Hyojae Jang ◽  
Hyung-Jin Kim ◽  
...  
Keyword(s):  
High Power ◽  
Linear Accelerator ◽  
Heavy Ion ◽  
Beam Dynamics

INVESTIGATION AND OPTIMIZATION OF LOW-ENERGY HEAVY-ION BEAM DYNAMICS IN PERIODIC AXISYMMETRICAL STRUCTURES WITH DC FOCUSING

2009 ◽  
Vol 24 (05) ◽  
pp. 843-856 ◽  
Author(s):  
VYACHESLAV SERGEEVICH DYUBKOV ◽  
EDUARD SERGEEVICH MASUNOV
Keyword(s):  
Ion Beam ◽  
Heavy Ion ◽  
Low Energy ◽  
Beam Dynamics ◽  
Smooth Approximation ◽  
Parameter Choice ◽  
Energy Beam ◽  
Beam Focusing ◽  
Spatially Periodic ◽  
Dynamics Stability

It is well-known that nonsynchronous harmonics of a RF field can focus particles. In order to focus ultra-low energy beam particles, a spatially periodic electrostatic field can be used, too. In this case the transverse focusing is provided by a periodic array of electrostatic lenses. This article is dedicated to questions of two high-current low-energy beam focusing types used in an injector-buncher of an ion linear accelerator, an application of a spatially periodic electrostatic focusing being examined for the first time. A two-dimensional nonlinear motion equation is derived in the Hamiltonian form in a smooth approximation. It allows us to study a correlation between the longitudinal and transverse ion beam dynamics at low energies. An investigation of the phase and transverse beam dynamics stability conditions in the initial part of the linac are given consideration. Conditions of the beam dynamics stability are found and analyzed. An approach to the field optimization problem is described. A method of the geometric parameter choice is worked out for a realization of the required field distributions in each structure. To verify the results of the beam dynamics stability analysis and optimized structure parameter choice, numerical simulations of low-energy heavy-ion beams are carried out.

Modification of Barium Cerate by Heavy Ion Irradiation

2013 ◽  
Vol 781-784 ◽  
pp. 357-361 ◽  
Author(s):  
Igor V. Khromushin ◽  
Taтiana I. Aksenova ◽  
Turgora Tuseyev ◽  
Karlygash K. Munasbaeva ◽  
Yuri V. Ermolaev ◽  
...  
Keyword(s):  
Structural Changes ◽  
Solid Phase ◽  
Ion Irradiation ◽  
Heavy Ion ◽  
High Energy ◽  
Low Energy ◽  
Barium Cerate ◽  
Weakly Bound ◽  
Ion Ranges ◽  
High Energy Ions

The effect of irradiation with heavy ions Ne, Ar, and Kr of various energies on the structure and properties of ceramic barium cerate doped with neodymium and annealed in air at 650°C for 7 hours is studied. It is noted that blistering was observed on cerate surface during its irradiation by low energy Ne ions, whereas it was not observed under low-energy Ar and Kr ions irradiation. Irradiation of the cerate with high energy ions caused partial amorphization of the irradiated surface of the material, while the structure of the non-irradiated surface did not change. In addition, the irradiated surface of the cerate endured solid-phase structural changes. Thus, upon high-energy ions irradiation in the range of Ne, Ar, Kr the cerate surface resembled the stages of spherulite formation - nucleation, growth (view of cauliflower), formation of spherulitic crust, respectively. The increase in water molecules release and reduction of molecular oxygen release from the barium cerate, irradiated by high-energy ions is found during vacuum constant rate heating. It is concluded that cerates undergo changes to the distances significantly exceeding the ion ranges in these materials. Features of high-energy ions influence on thermal desorption of carbon dioxide from cerates show, apparently, the formation of weakly bound carbonate compounds on the cerate surface in the irradiation process.

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