共查询到20条相似文献,搜索用时 312 毫秒
1.
LI Peng YUAN You-Jin MAO Li-Jun YANG Jian-Cheng LI Guo-Hong YIN Da-Yu LI Jie LI Xiao-Ni CHAI Wei-Ping SHI Jian 《中国物理C(英文版)》2011,35(2):183-187
Particles in a storage ring oscillate in the longitudinal and transverse dimensions.Therefore,the signal that beam has generated can be analyzed in the frequency domain to extract many beam parameters,such as tune,momentum spread,emittance and their evolution with time and so on.In this paper,the transverse spectrum in HIRFI-CSR was simulated and analyzed under different conditions,including electron cooling,hollow electron beam,solenoid effect,the tune shift caused by power supply ripple and the misalignment between ion and electron beams.The result of the simulation shows that the longitudinal magnetic field of the electron cooling device should be compensated by a "compensation solenoid",and the power supply ripple must be controlled,otherwise the accumulation would be affected and the beam would be lost. 相似文献
2.
H. Poth 《Zeitschrift für Physik A Hadrons and Nuclei》1987,326(4):483-486
It is shown that electron pick-up from a cooling electron beam can be used to extract an ion beam from a storage ring. The technique is described and extraction times are estimated. A few applications for medium-energy ion storage rings are given. 相似文献
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M. Kando Y. Fukuda H. Kotaki J. Koga S. V. Bulanov T. Tajima A. Chao R. Pitthan K. -P. Schuler A. G. Zhidkov K. Nemoto 《Journal of Experimental and Theoretical Physics》2007,105(5):916-926
We suggest a novel method for the injection of electrons into the acceleration phase of particle accelerators, producing low-emittance
beams appropriate even for the demanding high-energy linear collider specifications. We discuss the injection mechanism into
the acceleration phase of the wakefield in a plasma behind a high-intensity laser pulse, which takes advantage of the laser
polarization and focusing. The scheme uses the structurally stable regime of transverse wakewave breaking, when the electron
trajectory self-intersection leads to the formation of a flat electron bunch. As shown in three-dimensional particle-in-cell
simulations of the interaction of a laser pulse elongated in the transverse direction with an underdense plasma, the electrons
injected via the transverse wakewave breaking and accelerated by the wakewave perform betatron oscillations with different
amplitudes and frequencies along the two transverse coordinates. The polarization and focusing geometry lead to a way to produce
relativistic electron bunches with an asymmetric emittance (flat beam). An approach for generating flat laser-accelerated
ion beams is briefly discussed.
The text was submitted by the authors in English. 相似文献
6.
The effect of the electron transverse and longitudinal velocity spread at the entrance to the interaction space on wide-band chaotic oscillations in intense multiple-velocity beams is studied theoretically and numerically under the conditions of formation of a virtual cathode. It is found that an increase in the electron velocity spread causes chaotization of virtual cathode oscillations. An insight into physical processes taking place in a virtual-cathode multiple-velocity beam is gained by numerical simulation. The chaotization of the oscillations is shown to be associated with additional electron structures, which were separated out by constructing charged particle distribution functions. 相似文献
7.
HIRFL-CSR主环电子冷却模拟计算 总被引:2,自引:0,他引:2
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. 相似文献
8.
Laser cooling of heavy-ion beams in a storage ring is systematically studied with a multiparticle simulation code where not only exact lattice characteristics and space-charge forces but also realistic laser-ion interactions can be incorporated. The resonant coupling method is applied in order to extend the powerful longitudinal photon pressure to the transverse degrees of freedom. It is shown that, in spite of a space-charge-induced tune shift, the synchrobetatron resonance mechanism required for fast damping of transverse oscillations operates throughout the cooling process. Extremely efficient three-dimensional cooling of stored ion beams is thus feasible. It is demonstrated that, at low line density, normalized root-mean-squared emittances of the order of 10(-12) m.rad can be reached in all three directions by employing only existing technologies. 相似文献
9.
A. BondarevskayaA. Prozorov L. Labzowsky G. Plunien D. Liesen F. Bosch 《Physics Reports》2011,507(1):1-42
Theoretical concepts for the production, preservation and control of polarized highly charged ion beams in storage rings are investigated. It is argued that hydrogen-like ions can be polarized efficiently by optical pumping of the Zeeman sublevels of ground state hyperfine levels and that the maximum achievable nuclear polarization exceeds 90%. In order to study the preservation of the polarization during the ion motion through the magnetic system of the ring, the concept of the instantaneous quantization axis is introduced. It is suggested that the employment of “Siberian snakes” may help to preserve the ion beam polarization in the ring. The control of the beam polarization can be achieved by different methods: by measuring the Stokes parameters for the emitted photons or by observing the angular dependence of the transition rates for polarized ions. The important motivation for the production of polarized ion beams is the possibility to observe parity nonconservation effects in the hyperfine-quenched transitions in helium-like highly charged ions, where these effects can reach an unprecedented high value for atomic physics. The possible observation of parity nonconservation effects connected with the nuclear anapole moment is also discussed. A method for the observation of the electric dipole moment of an electron in a storage ring with a polarized highly charged ion beam is proposed. This method allows, in principle, to improve the existing boundaries for the electric dipole moment of an electron. However, the requirements of the corresponding experiment are very stringent. 相似文献
10.
Stancari G Valishev A Annala G Kuznetsov G Shiltsev V Still DA Vorobiev LG 《Physical review letters》2011,107(8):084802
A novel concept of controlled halo removal for intense high-energy beams in storage rings and colliders is presented. It is based on the interaction of the circulating beam with a 5-keV, magnetically confined, pulsed hollow electron beam in a 2-m-long section of the ring. The electrons enclose the circulating beam, kicking halo particles transversely and leaving the beam core unperturbed. By acting as a tunable diffusion enhancer and not as a hard aperture limitation, the hollow electron beam collimator extends conventional collimation systems beyond the intensity limits imposed by tolerable losses. The concept was tested experimentally at the Fermilab Tevatron proton-antiproton collider. The first results on the collimation of 980-GeV antiprotons are presented. 相似文献
11.
Smith J.R. Shokair I.R. Struve K.W. Schamiloglu E. Werner P.W. Lipinski R.J. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1991,19(5):850-854
An intense relativistic electron beam may be transported in low-pressure gas using an ion channel which focuses and guides the beam. The beam can be unstable to the growth of transverse oscillations caused by the electric force between the beam and channel-the ion hose instability. Beam propagation on channels created by photoionization of gas with an excimer laser is discussed. Ion hose oscillations have been recorded which have a betatron wavelength of approximately 1.5 m. The growth rate of the ion hose instability in the linear regime was measured as 1.67±0.45. At this level of growth, the amplitude of beam oscillations equals the channel radius after a period of one-third of an ion oscillation time 相似文献
12.
M. I. Bryzgunov V. Kamerdzhiev J. Li L. J. Mao V. V. Parkhomchuk V. B. Reva X. D. Yang H. Zhao 《Physics of Particles and Nuclei Letters》2017,14(4):615-623
Electron cooling is used for damping both transverse and longitudinal oscillations of heavy particle. The cooling of bunch ion beam (with RF voltage on) is important part of experiments with inner target, ion collision system, stacking and RF manipulation. The short length of an ion bunch increases the peak luminosity, gives a start-time point for using of the time-of-flight methods and obtains a short extraction beam pulse. This article describes the review of last experiments with electron cooling carried out on the CSRm, CSRe (China) and COSY (Germany) storage rings. The accumulated experience may be used for the project of electron cooler on 2.5 MeV (NICA) and 0.5 MeV HIAF for obtaining high luminosity, depressing beam-beam effects and RF manipulation. 相似文献
13.
S. I. Gubarev V. A. Koval’skii D. V. Kulakovskii I. V. Kukushkin M. N. Khannanov J. Smet K. von Klitzing 《JETP Letters》2004,80(2):124-129
The spectra of magnetoplasma excitations in two-dimensional electron disks and rings are studied by optical detection of resonance microwave absorption. For ring-shaped structures, two types of edge magnetoplasma modes localized along the inner and outer boundaries of the ring are observed. It is shown that the interaction between these modes leads to a strong modification of their magnetic-field dependences as compared to disks. In addition to the longitudinal edge magnetoplasma excitations, transverse plasma modes associated with the electron density oscillations along the ring radius are revealed. The spectra of magnetoplasma excitations are calculated in terms of the electrodynamic theory for both ring-shaped and disk-shaped structures. The classification of all modes of collective magnetoplasma excitations observed in the experiment is performed on the basis of the comparison between experimental and theoretical results. 相似文献
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An electron cooler designed at the Budker Institute of Nuclear Physics for the Cooler Synchrotron COSY (Juelich, Germany) has been put into operation. The aim of this cooling device is to prevent the beam scattering on an internal target up to the maximal energy of the transmitted beam. The device provides cooling in a strong longitudinal magnetic field generated in a high-voltage area. The motion of electrons in the magnetic field considerably improves the kinetics of electron—ion collisions, because their transverse velocity component (which is very high as a rule) does not participate in the process. First experiments on electron beam cooling on energy 200 MeV were made in 2013. Early in 2014, sessions on electron beam cooling to 200, 350, 580, and 1660 MeV were carried out. In other experiments, deuterium beams were cooled down. Experimental data for the cooling time are compared with the respective theoretical predictions. These results may be used in cooling projects for the Nuclotron-based Ion Collider fAcility (NICA), Joint Institute for Nuclear Research, Dubna, Russia, and the Facility for Antiproton and Ion Research (FAIR), Darmstadt, Germany. 相似文献
16.
YANG Xiao-Dong MAO Li-Jun LI Guo-Hong LI Jie MA Xiao-Ming YAN Tai-Lai YUAN You-Jin SONG Ming-Tao YANG Jian-Cheng LIU Yong ZHAO Tie-Cheng XIA Jia-Wen ZHANG Wei GAO Da-Qing ZHOU Zhong-Zu YAN Hong-Bin MAO Rui-Shi HE Yuan HAN Shao-Fei ZHENG Jian-Hua YANG Xiao-Tian ZHAO Hong-Wei XIAO Guo-Qing YIN Da-Yu LI Peng JIA Huan Parkhomchuk Vasily Reva Vladimir Skorobogatov Dmitry 《中国物理C(英文版)》2010,34(7)
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. 相似文献
17.
We propose a scheme for tapered laser cooling of coasting ion beams in storage rings. Tapered cooling has recently been shown to be crucial for attaining crystalline ion beams. The scheme proposed here, based on a relative displacement of a co- and a counterpropagating Gaussian laser beam, gives a radial variation in the equilibrium velocities to which particles are cooled. The variation is approximately linear in a relatively large range transverse to the laser beams. Expressions for the spatially dependent equilibrium velocities and the range of the tapered cooling forces are derived. We discuss the dependence on laser beam parameters as well as the limitations of this cooling scheme. 相似文献
18.
The cooling of particles in storage rings depends on the coupling between the longitudinal and transverse “temperatures” of the stored beam. This coupling is studied in the limit of relatively sparse beams, and is found to depend sensitively on the relative strengths of the focusing forces in the two transverse dimensions, which determine the ratio of the periods of the betatron oscillations. 相似文献
19.
An investigation is made of the interaction between a test charge and an electron beam which is convectively unstable against
plasma oscillations. An analysis is made of the negative-mass instability of the longitudinal motion. Expressions are derived
for the reaction force exerted by the electron plasma polarized by the moving charge and for the diffusion tensor arising
from electric field fluctuations. The approximation of uniform rectilinear motion of a test particle is used to estimate the
systematic and diffusion components of the rates of change in its energy. It is shown that in this case, interaction with
an unstable electron beam leads to acceleration of the particle in respect to the longitudinal degree of freedom (antifriction)
and under certain conditions enhances the friction effect (cooling) in respect to the transverse degrees of freedom. An assessment
is made of the possibility of obtaining an overall positive friction effect by using a special “sweeping” procedure whereby
the longitudinal velocity of the electron beam is changed in a specific manner consistent with the cooling process.
Zh. Tekh. Fiz. 67, 58–61 (November 1997) 相似文献
20.
A. B. Kuznetsov I. N. Meshkov A. V. Philippov 《Physics of Particles and Nuclei Letters》2012,9(4-5):346-351
Experimental data on rates for the radiative recombination of nuclei (from helium to uranium) and various ions in interaction with an electron beam in electron cooling systems are reviewed. An analysis of the experimental data has yielded the dependence of the radiative recombination rate on the relative electron energy appreciably differently than the theoretical models obtained earlier by H. Kramers and R. Schuch. In addition, it is shown that the radiative recombination rate of nuclei in the experiment depends on the transverse electron energy as T ?? ?0.82 ,which is also different from the results of the calculations by the theoretical model proposed by M. Bell and J. Bell. Experimental data on the cooling of ions in intermediate charge states are analyzed and the dependence of the radiative recombination rate on the charge state of the ion (electron-shell configuration) is shown. For some ion charge states, the rate of the process is of a resonance character. Loss to radiative recombination in the electron cooling system of the NICA Booster is evaluated for the Au32+, Au33+, Au50+, and Au51+ ion beams. Limitations imposed on the Au79+ beam lifetime by radiative recombination in the electron cooling system of the NICA Collider are analyzed. Possible ways to decrease the radiative recombination rate of nuclei by selecting the parameters of the electron cooling system for the NICA Collider are proposed. 相似文献