Control system design for new electronic cooler of HIRFL-CSRm

Introduction In this paper,we detail the architecture,design,and testing of an accurate and usable electronic cooler control system for the cooling storage main ring at the Heavy Ion Research Facility,Lanzhou,China(HIRFL-CSRm),and present the results of its use.Purpose A control system must manage devices with a high degree of accuracy to satisfy various physical requirements,and to ensure the accuracy of the data acquisition and control characteristics.Methods and materials The software for the system,based on the C++,was developed following the model-view-controller architecture pattern.On the hardware side,an I-7017R module was adopted for analog-to-digital conversion and an I-7065D module for electronic delay.The communication protocol was analyzed,discussed,and implemented.Results The control system was then tested with the 12C3+carbon beam at HIRFL-CSRm.The fast reaction time and high-precision data processing exhibited during beam tuning verified the stability and maintainability of the proposed control system.

Design of an efficient collector for the HIAF electron cooling system

A collector with high perveance,efficient recu-peration,and low secondary emissions is required for the 450-keV electron cooler in the HIAF accelerator complex.To optimize the collection efficiency of the collector,a simulation program,based on the Monte Carlo simulations,was developed in the world’s first attempt to calculate the electron collection efficiency.In this program,the backscattering electrons and secondary electrons generated on the collector surface are calculated using a Monte Carlo approach,and all electron trajectories in the collector region are tracked by the Runge–Kutta method.In this paper,the features and structure of our program are described.The backscattering electron yields,with various collector surface materials,are calculated using our pro-gram.Moreover,the collector efficiencies for various col-lector structures and electromagnetic fields are simulated and optimized.The measurement results of the collection efficiency of the HIAF collector prototype and the CSRm synchrotron are also reported.These experimental results were in good agreement with the simulation results of our program.

Side-effects of the space charge field introduced by a hollow electron beam in the electron cooler of CSRm

An electron cooler is used to improve the quMity of the ion beam in a synchrotron; however it also introduces a nonlinear electromagnetic field to the accelerator, which causes tune shift, tune spread and may drive resonances leading to ion beam loss. In this paper the tune shift and the tune spread caused by the nonlinear electromagnetic field of a hollow electron beam is investigated, and the resonance driving terms of the nonlinear electromagnetic field are analysed. The differences are presented compared with a solid electron beam. Calculations are performed for 23SU32＋ ions of energy 1.272 MeV stored in the main Cooler Storage Ring （CSRm） at the Institute of Modern Physics, Lanzhou. It is found that in this situation the nonlinear field caused by the hollow electron beam does not lead to serious resonances.

Low energy range dielectronic recombination of Fluorine-like Fe^17+at the CSRm

The accuracy of dielectronic recombination （DR） data for astrophysics related ions plays a key role in astrophysical plasma modeling. The absolute DR rate coefficient of Fe^17＋ ions was measured at the main cooler storage ring at the Institute of Modern Physics, Lanzhou, China. The experimental electron-ion collision energy range covers the first Rydberg series up to n = 24 for the DR resonances associated with the 2p1/2 →^2 p3/2△n= 0 core excitations. A theoretical calculation was performed by using FAC code and compared with the measured DR rate coefficient. Overall reasonable agreement was found between the experimental results and calculations. Moreover, the plasma rate coefficient was deduced from the experimental DR rate coefficient and compared with the available results from the literature. At the low energy range, significant discrepancies were found, and the measured resonances challenge state-of-the-art theory at low collision energies.