Diagnostics and electron-optics of a high current electron beam in the Tandem free electron laser — status report (original) (raw)
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Electron Beam Guns for High Energy Electron Accelerators: An Overview
Journal of Modern Physics, 2013
Thermionic electron beam is a fundamental part of all types of linear accelerators around the world in the field of Experimental High Energy Physics. Thermionic beam is very inexpensive and simple to produce. In this work, we give an overview of generation, design and applications of the electron beam with particular reference to e-beam generation at high energy linear accelerators. Experimental data are presented in tabular form for ready reference. We also make an evaluation of these high energy sources with our in-house designed e-beam gun. Finally, a comparison has been presented in terms of characteristic parameters of all these high performance sources.
Second International Conference on high-Power Electron and Ion Beams
Soviet Atomic Energy, 1978
The second conference, held in October 1977 at Ithaca (U.S.A.), was attended by 206 delegates from the U.S.A., the USSR, France, Israel, Japan, Great Britain, the Netherlands, and the Federal Republic Germany. A total of 74 papers were presented on the following topics, Investigation of Temperature Signaling Devices with Inertial Plasma Retention in the Case of Target Heating by Electron and Ion Beams
Design and beam dynamics of a Transmission Electron Microscope electron gun assembly
Vacuum, 2019
We present the design and beam dynamics analysis of a Transmission Electron Microscope illumination system. A LaB 6 emitter is used as a cathode/source with an emissive surface area of diameter 50 µm generating fixed emission current of 5 mA which is biased by-300V with Wehnelt electrode. The gun is comprised of five electrostatic lenses in-between the focusing and anode electrodes to accelerate and focus the beam with integrated energy of 160 keV in the post anode region with diameter around 228 µm. Finally, the beam is focused using the condensed electromagnetic lenses of field strengths 183 mT and 331 mT, respectively to spot size 1.8 µm in the post-lens position. The obtained focal spots are largely symmetric along the two transverse directions. The illumination system geometry offers full beam collimation control. The study provides a theoretical basis for the structure and optics design of the Transmission Electron Microscope．
1995
Under this CRADA we have carried out a joint research and development program between the Accelerator Test Facility at the National Synchrotron Light Source Department at Brookhaven National Laboratory and Northrop-Grumman Corporate Research Cmter of Princeton New Jersey. The subject of this research was the development of an advanced laser photocathode RF electron gun for the generation of high brighbress electron beams. The intent of this work was to enhance the performance of the electron gun recentþ developed at Brookhaven
2002
We are proposing an Atto-second electron beam generation and diagnostics experiment at the Brookhaven Accelerator Test facility (ATF) using 1 µm Inverse Free Electron Laser (IFEL). The proposed experiment will be carried out by an BNL/LBNL collaboration, and it will be installed at the ATF beam line II. The proposed experiment will employ a one-meter long undulator with 1.8 cm period (VISA undulator). The electron beam energy will be 63 MeV with emittance less than 2 mm-mrad and energy spread less than 0.05%. The ATF photocathode injector driving laser will be used for energy modulation by Inverse Free Electron Laser (IFEL). With 10 MW laser peak power, about 2 % total energy modulation is expected. The energy modulated electron beam will be further bunched through either a drift space or a three magnet chicane into atto-second electron bunches. The attosecond electron beam bunches will be analyzed using the coherent transition radiation (CTR).
Non-invasive Beam Detection in a High Average Power Electron Accelerator
CLEO: 2014, 2014
For a free-electron laser (FEL) to work effectively the electron beam quality must meet exceptional standards. In the case of an FEL operating at infrared wavelengths the critical phase space tends to be in the longitudinal direction. Achieving high enough longitudinal phase space density directly from the electron injector system in an FEL is difficult due to space charge effects, thus one needs to manipulate the longitudinal phase space once the beam energy reaches a sufficiently high value. However, this is fraught with problems. Longitudinal space charge and coherent synchrotron radiation can both disrupt the overall phase space, furthermore, the phase space disruption is exacerbated by the longitudinal phase space manipulation process required to achieve high peak current. To achieve and maintain good FEL performance one needs to investigate the longitudinal emittance and be able to measure it during operation preferably in a noninvasive manner. Using electro-optical (EO) methods, we plan to measure the bunch longitudinal profile of an energy (~120-MeV), high-power (~10kW or more average FEL output power) beam. Such a diagnostic could be critical in efforts to diagnose and help mitigate deleterious beam effects for high output power FELs.
Optics Design and Layout for the Electron Beam Test Facility at Daresbury Laboratory
An Electron Beam Test Facility (EBTF) is being developed at Daresbury Laboratory [1] to provide the beam for scientific and industrial applications and as a front end of FEL test facility under consideration at Daresbury . It is based on a RF photoinjector which delivers a ~6 MeV beam. The photoinjector design in the first phase consists of a 2.5 cell S-band RF gun to be driven by Ti:Sapphire laser. The design is aimed to deliver bunches at 10-250 pC charge with low transverse emittances and ultrashort lengths. The beam transport optics design described in this paper includes a dedicated diagnostics section capable of characterising ultra short and ultra low emittance bunches and beam transport lines to two user areas.
Transverse emittance studies of an induction accelerator of heavy ions
Conference Record of the 1991 IEEE Particle Accelerator Conference
achieved in practice. These experiments, in which the current Current amplification of heavy ion beams is an integral was amplified from 4x10 mA to 4x90 mA and the energy feature of the induction linac approach to heavy ion fusion. As increased from 200 keV (the injection value) to 900 keV, were part of the Heavy Ion Fusion Accelerator Research program at accompanied by a growth in the normalised emittance by a LBL we have been studying the evolution of die transverse factor of approximately two. This work has been reported emittance of ion beams while they are undergoing current previously and a review can be found elsewhere in these amplification, achieved by longitudinal bunch compression and proceedings'. acceleration. Experiments are conducted on MBE-4, a four beam Cs + induction linac. The space-charge dominated beams 2. EXPERIMENTS of MBE-4 are focused by electrostatic quadrupoles while they are accelerated tram nominally 200 keV up to-1 MeV by 24 We have identified a number of mechanisms which may accelerating gaps. Initially the beams have currents of typically be responsible for emittance growth in MBE-4 including 4 mA to 10 mA per beam. Early experimental results showed matching errors, rapid longitudinal compression (leading to a a growth of the normalized emittance by a factor of 2 while die change in die space-charge electrostatic-field energy), and nonbeam current was amplified by up to 9 times its initial value, linear field effects (self-fields, image-fields, focus fields). The We will discuss me results of recent experiments in which a last of Uiese mechanisms is particularly troublesome for offmild bunch length compression rate, more typical of that axis beams where the edge of the beam may approach the nonrequired by a fusion driver, has shown that the normalized linear field region of the quadrupoles 2. For die experiments emittance can be maintained at its injection value (0.03 mm-discussed here offsets are minimised by the use of steering mr) during acceleration. elements at die entrance to the linac and by careful alignment of the accelerator. Proper matching of the beam phase-space to 1. INTRODUCTION the lattice of die linac is performed by adjustment of ^'matching section" consisting of eight electrostatic The induction Unac approach to heavy ion driven inertial quadrupoles just downstream of thediode. fusion envisages a design in which multiple beams are Recent experiments have involved the application of an employed at the law energy end of the driver with die beam acceleration schedule which results in a smaller increase in die current undergoing amplification as it is accelerated. Current beam line charge density between injection and full energy. In amplification results both from the increase in panicle velocity order to realise this we have reduced the extent of die applied and also from longitudinal bunch compression. This velocity tilt in the early pps of MBE-4 with the majority of compression is achieved by applying a velocity 'tilt' between die acceleration being provided by waveforms in which die die head and tail of the bunch, provided by tailored voltage voltage does not vary greatly during die passage of die beam waveforms applied at die accelerating gaps. MBE-4 is a four pulse. The reduction in bunch compression in these beam Cs* linac built to investigate longitudinal dynamics experiments means that the beam pulse length is not issues related to this concept. The linac is comprised of a 30 sufficiently short for the final accelerating waveforms to period, electrostatic, AG focusing lattice. Each doublet is completely straddle the beam pulse. Consequently die current followed by an accelerating gap with die exception of every waveforms observed in diese experiments are poorer dian those fifth doublet where the gap is reserved for diagnostic access and obtained in earlier studies, however me focus of these vacuum pumping. Each lattice period (l.p.) is 45.7 cm long experiments is transverse beam dynamics, resulting in a linac of 13.7 metres. Early experiments on MBE-4 concentrated on a In attempting to maintain a matched beam during demonstration of current amplification while maintaining acceleration we scale the strengths of die quadrupoie focusing control of die current profile and correcting for inevitable voltages, Vq, such as to keep diem proportional to die beam acceleration errors', which arose from the difference between lfae-charge density, X, i.e. V Q-\-1 / v, where I and v are ideal accelerating pulser waveforms and those waveforms Ae