HIRFL-CSR 实验环电子冷却装置参数优化

以400MeV/u的238U91为例,用电子冷却模拟程序计算了冷却时间随冷却段长度、冷却段磁感应强度、磁场平行度、电子密度、电子束半径、电子温度的变化规律,并分析了影响冷却时间的因素,获得了电子冷却装置最优参数。     

HIRFL-CSR主环电子冷却模拟计算

以¹⁶O⁸⁺为例,用电子冷却模拟程序计算了冷却时间随离子能量、初始发射度、初始动量分散、离子流强以及离子电荷态的变化规律,研究了储存环在冷却段的β函数和色散函数对冷却时间的影响.     

HIRFL-CSR实验环电子冷却装置磁场测量

 在HIRFL-CSR实验环电子冷却装置上采用了独立的高精度螺线管串联产生纵向磁场的设计,获得很高的冷却段磁场平行度。使用霍尔片测量磁场的分布,使用磁针测磁方法测量冷却段磁场的磁轴偏角,并根据测量及计算结果对单个线圈磁轴进行微调。测量及调试结果表明,在施加电流为额定电流的一半时,冷却段磁感应强度为0.078 T,剩余磁场小于2×10^-4 T,磁场不平行度小于1×10^-4,达到了预期的设计目标。     

HIRFL-CSR实验环电子冷却装置磁场测量

在HIRFL-CSR实验环电子冷却装置上采用了独立的高精度螺线管串联产生纵向磁场的设计,获得很高的冷却段磁场平行度。使用霍尔片测量磁场的分布,使用磁针测磁方法测量冷却段磁场的磁轴偏角,并根据测量及计算结果对单个线圈磁轴进行微调。测量及调试结果表明,在施加电流为额定电流的一半时,冷却段磁感应强度为0.078 T,剩余磁场小于2×10-4 T,磁场不平行度小于1×10-4,达到了预期的设计目标。     

HIRFL-CSR电子冷却束流位置测量系统

高效率的电子冷却过程, 要求电子束与离子束位置平行且重叠。 为了同时测量电子束与离子束的位置, 在HIRFL CSR电子冷却装置上研发了以容性圆筒形极板为感应电极的束流位置探测系统。 系统测量束流通过探针时产生的脉冲感应信号, 并进行傅里叶变换得到频谱信号, 分析4个不同电极上频谱信号强度获取束流的位置信息。 测量结果表明, 该束流位置探测系统测量准确, 为定量研究储存环离子累积和电子冷却过程与两种束流相对位置及角度的依赖关系提供了条件。 The efficient electron cooling requires that the ion beam and electron beam are parallel and overlapped. In order to measure the positions of ion beam and electron beam simultaneously, a beam position monitor system is developed for the HIRFL-CSR electron cooler device, which probe consists of four capacitive cylinder linear cut poles. One can get the both beam positions from the picking up signals of four poles by using Fourier transform(FFT) method. The measurement results show that the beam position monitor system is accurate. This system is suitable for investigating the relation between electron cooling processing and the angle of ion beam and electron beam.     

电子冷却

本文概述电子冷却原理及其国际现状。     

电子冷却

本文概述电子冷却原理及其国际现状.This paper briefly describes the principle of electron cooling and the current status.     

储存环内电子冷却过程模拟

考虑储存环内离子的横向振荡和纵向振荡的运动特性,模拟了HIRFL-CSR内重离子束的电子冷却过程.给出了离子束的横向发射度和纵向动量散度随时间连续变化的图象,由此分析了电子束的空间电荷效应,冷却段色散函数和横向电子束温度对冷却过程快慢的影响.     

CSR实验环电子冷却装置的纵向电子束温度

电子冷却装置中, 电子束纵向温度是计算冷却力的主要参量之一. 当电子与被冷却离子的相对速度很小时, 纵向冷却力与离子速度呈线性关系, 并且线性区域的宽度与电子束纵向温度有关. 通过分析影响电子束纵向温度的主要因素, 得到了兰州重离子冷却储存环实验环(CSRe)电子冷却装置中电子束纵向温度的大小.     

HIRFL-CSR电子冷却系统

建议中的兰州重离子加速器冷却贮存环（ＨＩＲＦＬ－ＣＳＲ）拟采用电子冷却方法将重离子束冷却到３００ＭｅＶ／ｕ．最高电子能量为１６５ｋｅＶ,最大电子电流密度为０．２４４Ａ／ｃｍ２．叙述了ＣＳＲ电子冷却装置的初步方案． Electron cooling technique will be applied to the proposed Lanzhou heavy ion cooler-storage ring(HIRFL-CSR).A electron cooling device with a max-imum electron energy of 165keV and maximum current density of 0.244A/cm2 is planned to cool heavy ions up to energies of 300MeV/u.The prelimnary design for the cooling system is presented.     

加速器电子冷却技术现状及最新进展

一个世纪以来,人类对新物理、新现象和新结构研究的不懈追求,促使粒子加速器始终向高能量、高流强和高束流品质方向发展。束流冷却技术作为提高束流品质和亮度的最有效手段,是决定加速器性能和实验精度的关键。随着国际一系列高能离子加速器的发展需求,尤其是新一代大科学装置——电子离子对撞机(美国EIC, 中国EicC)对高对撞亮度的需求,束流冷却技术在中高能量区间(离子能量>GeV/u)面临重大挑战。作为最具潜力解决方案之一,电子冷却技术是目前国内外研究的重要突破方向,一系列新理论、新方案和新问题亟需被验证和深入研究。针对未来中高能量下的束流冷却,本文介绍了近年来电子冷却技术的最新进展,并对相关装置和实验进行了简要概述,同时也对未来高能电子冷却技术的发展进行了讨论。     

CSRm随机冷却初步设计

根据实际情况对兰州重离子加速器冷却储存环主环随机冷却做了初步设计和优化, 用冷却方程对主环随机冷却做了详细的数值模拟计算. 研究表明, 随机冷却对主环束流冷却速度很快, 冷却效果很好. 通过对电子冷却和随机冷却的比较, 提出主环的束流冷却采用电子冷却和随机冷却相结合的办法, 这样可以加快冷却速度, 得到更高流强、更好品质的束流.     

Commissioning of electron cooling in CSRm

A new generation electron cooler has started operation in the heavy ion synchrotron CSRm which is used to increase the intensity of heavy ions. Transverse cooling of the ion beam after horizontal multi-turn injection allows beam accumulation at the injection energy. After optimization of the accumulation process an intensity increase in a synchrotron pulse by more than one order of magnitude has been achieved. In given accumulation time interval of 10 seconds, 108 particles have been accumulated and accelerated to the final energy. The momentum spread after accumulation and acceleration in the 10-4 range has been demonstrated in six species of ion beams. Primary measurements of accumulation process varying with electron energy, electron beam current, electron beam profile, expansion factor and injection interval have been performed. The lifetimes of ion beams in the presence of electron beams were roughly measured with the help of DCCT signal.     

Commissioning of electron cooling in CSRe

The 400 MeV/u 12C6+ion beam was successfully cooled by the intensive electron beam near 1 A in CSRe.The momentum cooling time was estimated near 15 s.The cooling force was measured in the cases of different electron beam profiles,and the different angles between the ion beam and electron beam.The lifetime of the ion beam in CSRe was over 80 h.The dispersion in the cooling section was confirmed as positive close to zero.The beam sizes before cooling and after cooling were measured by the moving screen.The beam diameter after cooling was about 1 mm.The bunch length was measured with the help of the signals from the beam position monitor.The diffusion was studied in the absence of the electron beam.     

Simulation of relaxation processes in electron beams at high magnetic fields

Molecular-dynamics simulations of relaxation processes in electron beams at high magnetic fields are presented. The result of the longitudinal–longitudinal relaxation and the rate of the transverse–longitudinal relaxation are calculated for magnetic fields between 0.006 and 0.1 T for electron beam parameters typical of those in low-energy electron coolers. Comparisons with theoretical and experimental values are made. This revised version was published online in July 2006 with corrections to the Cover Date.