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Analytical treatment of the nonlinear electron cloud effect and the combined effects with beam-beam and space charge nonlinear forces in storage rings

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Chinese Physics C 2009年第2期33卷 135-144页

作者：高杰 Institute of High Energy Physics CAS

In this paper we treat first some nonlinear beam dynamics problems in storage rings, such as beam dynamic apertures due to magnetic multipoles, wiggles, beam-beam effects, nonlinear space charge effect, and then nonlinear electron cloud effect combined with beam-beam and space charge effects, analytically. This analytical treatment is applied to BEPC II. The corresponding analytical expressions developed in this paper are useful both in understanding the physics behind these problems and also in making practical quick hand estimations.

关键词： electron cloud effect beam-beam effect space charge effect storage ring BEPC II

An emittance measurement device for a space-charge dominated electron beam

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Chinese Physics C 2012年第9期36卷 867-870页

作者：王文静黄森林全胜文林林刘克新 State Key Laboratory of Nuclear Physics and Technology Peking University

Beam emittance is one of the most important parameters for electron sources. To investigate the beam emittance of the 3.5-cell DC-SC photocathode injector developed at Peking University, a multi-slit emittance measurement device has been designed and manufactured. The designed slit width, mask thickness and beamlet drift length are 100 ~m, 3 mm and 430 mm respectively. It is suitable for the electron beam with energy of about 5 MeV and the average current less than 0.1 mA. The preliminary measurement result of the rms emittance of the electron beam produced by the DC-SC injector is about 5 7 ***.

关键词： emittance measurement multi-slit space charge effect DC-SC photocathode injector

Emittance-dominated long bunches in dual harmonic RF system

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Chinese Physics C 2008年第1期32卷 60-66页

作者：安世忠 Klaus Bongardt Rudolf Maier 唐靖宇张天爵 China Institute of Atomic Energy IKP FZ Juelich 52425 JuelichGermany Institute of High Energy Physics CAS

The storage of long bunches for long time intervals needs flattened stationary buckets with a large bucket height. The longitudinal motion of the initially mismatched beam has been studied for both the single and dual harmonic RF systems. The RF amplitude is determined to be r.m.s wise matched. The bucket height of the single harmonic system is too small even for shorter bunch with only 20% increased energy spread. The Halo formation and even debunching can be seen after a few synchrotron periods for single particles with large amplitude. In the case of small energy spread for a cooled beam, Coulomb interaction cannot be ignored. The external voltage has to be increased to keep the r.m.s bunch length unchanged. The new voltage ratio R（N） simplifies physics for the emittance-dominated bunches with modest particle number N. For the single harmonic system, substantial amount of debunching occurs without increasing the external voltage, but very little if the RF amplitude is doubled. Results from the ORBIT tracking code are presented for the 1 GeV bunch in the HESR synchrotron, part of the GSI FAIR project.

关键词： bucket height mismatch space charge effect debunching

Computer simulations for intense continuous beam transport in electrostatic lens systems

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Chinese Physics C 2008年第9期32卷 750-753页

作者：赵小松吕建钦 State key Laboratory of Nuclear Physics and Technology Peking University

A code LEADS based on the Lie algebraic analysis for the continuous beam dynamics with space charge effect in beam transport has been developed. The program is used for the simulations of axial-symmetric and unsymmetrical intense continuous beam in the channels including drift spaces, electrostatic lenses and DC electrostatic accelerating tubes. In order to get the accuracy required, all elements are divided into many small segments, and the electric field in the segments is regarded as uniform field, and the dividing points are treated as thin lenses. Iteration procedures are adopted in the program to obtain self-consistent solutions. The code can be used in the designs of low energy beam transport systems, electrostatic accelerators and ion implantation machines.

关键词： intense continuous beam axial-symmetric electrostatic field Lie algebraic analysis space charge effect

Lie algebraic analysis for the nonlinear transport of intense bunched beam in electrostatic quadrupoles

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Chinese Physics C 2008年第3期32卷 209-214页

作者：张卓吕建钦 Institute of Heavy Ion Physics Peking UniversityBeijing 100871China Institute of Fluid PhysicsChina Academy of Engineering PhysicsMianyang 621900China Institute of Heavy Ion Physics Peking UniversityBeijing 100871China

In this paper, the nonlinear transport of intense bunched beams in electrostatic quadrupoles is analyzed using the Lie algebraic method, and the results are briefly presented of the linear matrix approximation and the second order correction of particle trajectory in the state space. Beam having K-V distribution and Gaussian distribution approximation are respectively considered. A brief discussion is also given of the total effects of the quadrupole and the space charge forces on the evolution of the beam envelope.

关键词： electrostatic quadrupole space charge effect Lie algebraic nonlinearity

Design of Electrostatic Focusing for space Electron Beam Welding Gun

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Chinese Journal of Aeronautics 2005年第3期18卷 256-262页

作者：李春旭何成旦许启晋蒋彩云 State Key Lab of Advanced Non-ferrous Materials Lanzhou University of Technology Lanzhou 730050 ChinaCollege of Materials Science and Engineering Lanzhou University of Science and Technology Lanzhou 730050 China State Key Lab of Advanced Non-ferrous Materials Lanzhou University of Technology Lanzhou 730050 ChinaLanzhou Physics Institute Lanzhou 730000 China Lanzhou Physics Institute Lanzhou 730000 China State Key Lab of Advanced Non-ferrous Materials Lanzhou University of Technology Lanzhou 730050 China

The developmental situation of space welding technology at home and abroad is introduced. Then it is put forward that the designing scheme and the computer aided design （CAD） method of main single lens of the domestic space electron beam gun with equal-diameter three-cylinder simple lens, and the flowing-pipe way of calculating the space charge density of the main lens area ,in the electron gun is analyzed. The parameters calculation of the focusing system is completed through Language C utilizing computer programming and a satisfying result is gotten. The result shows that the calculation and design method are correct ： the dispersed focusing current of electron beam is less, the beam section is less in the deflected magnetic field, the minimal radius of beam spot on the workpiece is about 0.65615mm, and all these can meet the requirements of the space welding and cutting.

关键词： space welding three-cylinder single lens CAD space charge effect

effects of Thickness on the Electrical Conductivity of Sputtered YSZ Film with Nanocrystalline Columnar Microstructure

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Journal of Wuhan University of Technology(Materials Science) 2018年第6期33卷 1344-1349页

作者： YANG Qingqing MENG Bin Faculty of Materials Science & Engineering Kunming University of Science & Technology

In order to investigate the effect of the thickness on the electrical conductivity of yttriastabilized zirconia(YSZ) film, the nanocrystalline columnar-structured YSZ film with thickness of 0.67-2.52 μm was prepared by magnetron sputtering through controlling the deposition time. All the sputtered films with different thicknesses consist of the main phase of cubic YSZ as well as a small amount of monoclinic YSZ. The thicker films exhibit a typical columnar grain structure based on the fractured cross-sectional SEM observations. The average diameters of columnar grains increase from about 40 nm to 100 nm with the film thickness from 0.67 μm to 2.52 μm according to TEM analysis. The thinnest YSZ film with 0.67 μm thickness shows the highest apparent electrical conductivity in the four films in 400-800 ℃ due to the contribution from the highly conductive film/substrate interfacial region. On the other hand, the real electrical conductivities of YSZ films increase with film thickness from 0.67 μm to 2.52 μm after eliminating the contribution of the film/substrate interface. The increasing film thickness leads to the grain growth as well as the decrement in the volumetric fraction of the resistive columnar grain boundary and a consequent higher real electrical conductivity.

关键词： YSZ film columnar microstructure magnetron sputtering interface effect space charge effect

Quadrupole-Linear Ion Trap Tandem Mass Spectrometry System for Clinical Biomarker Analysis

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Engineering 2022年第9期16卷 56-64页

作者： Xiang Fang Jie Xie Shiying Chu You Jiang Yuting An Chang Li Xiaoyun Gong Rui Zhai Zejian Huang Chunling Qiu Xinhua Dai Technology Innovation Center of Mass Spectrometry for State Market Regulation Center for Advanced Measurement ScienceNational Institute of MetrologyBeijing 100029China College of Instrument Science and Electrical Engineering Jilin UniversityChangchun 130026China

The accurate and efficient measurement of small molecule disease markers for clinical diagnosis is of great *** this study,a quadrupole-linear ion trap(Q-LIT)tandem mass spectrometer was designed and built in our *** precursor ions were first selected in the quadrupole,and then injected,trapped,and fragmented simultaneously in the linear ion trap(LIT)to reduce the space charge effect,enrich the target product ions,and promote *** targeted analytes were measured with selected reaction monitoring using a positive scan mode with electrospray ionization(ESI).Ions with a mass-to-charge ratio(m/z)ranging from 195 to 2022 were *** scanning at 1218amu.s^(-1),unit resolution and an accuracy of higher than m/z 0.28 was obtained for m/z up to *** dimensionless Mathieu parameter(q)value used in this study was 0.40 for collision-induced dissociation(CID),which was activated by resonance *** an overall CID efficiency of 64%was achieved(activation time,50 ms).Guanidinoacetic acid(GAA)and creatine(CRE)were used as model compounds for small molecule clinical *** limits of quantification were 1.0 and 0.2 nmol.L^(-1)for GAA and CRE,respectively.A total of 77 actual samples were successfully analyzed by the home-built ESI-Q-LIT tandem mass spectrometry *** developed method can reduce matrix interference,minimize space charge effects,and avoid the chromatographic separation of complex samples to simplify the pretreatment *** novel Q-LIT system is expected to be a good candidate for the determination of biomarkers in clinical diagnosis and therapeutics.

关键词： Linear ion trap Quadrupole space charge effect Collision-induced dissociation Biomarker

A Particle-in-cell scheme of the RFQ in the SSC-Linac

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Chinese Physics C 2010年第11期34卷 1749-1753页

作者：肖陈何源陆元荣 Yuri Batygin 尹苓玉志军原有进刘勇常玮杜小楠王智夏佳文 Graduate University of Chinese Academy of Sciences Institute of Modern Physics Chinese Academy of Sciences Key Laboratory of Heavy Ion Physics Ministry of Education Los Alamos National Laboratory Los AlamosNM87545USA The School of Nuclear Science and Technology Lanzhou University

A 52 MHz Radio Frequency Quadrupole （RFQ） linear accelerator （linac） is designed to serve as an initial structure for the SSC-Linac system （injector into Separated Sector Cyclotron）.The designed injection and output energy are 3.5 keV/u and 143 keV/u,*** beam dynamics in this RFQ have been studied using a three-dimensional Particle-In-Cell （PIC） code *** results show that this RFQ structure is characterized by stable values of beam transmission effciency （at least 95%） for both zerocurrent mode and the space charge dominated *** beam accelerated in the RFQ has good quality in both transverse and longitudinal directions,and could easily be accepted by Drift Tube Linac （DTL）.The effect of the vane error and that of the space charge on the beam parameters have been studied as well to define the engineering tolerance for RFQ vane machining and alignment.

关键词： RFQ PIC mode parameters sweep analysis manufacturing error space charge effect