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Thermionic gun

A direct current, electrostatic thermionic electron gun is formed from several parts: a hot cathode, which is heated to create a stream of electrons via thermionic emission, electrodes generating an electric field to focus the electron beam (such as a Wehnelt cylinder), and one or more anode electrodes which accelerate and further focus the beam. A large voltage difference between the cathode and anode accelerates the electrons away from the cathode. A repulsive ring placed. Conventional thermionic microwave and radio frequency (RF) guns can offer high average beam current, which is important for synchrotron light and terahertz (THz) radiation source facilities, as well as for industrial applications. For example, the Advanced Photon Source at Argonne National Laboratory is a national synchrotron-radiation light source research facility that utilizes thermionic RF guns. However, these existing thermionic guns are bulky, difficult to handle and install.

Electron gun - Wikipedi

Standard thermionic guns for accelerator applications require complex, real-estate-consuming, bunching systems in order to produce high-quality electron beams and achieve low electron beam loss in the accelerating structures. Photocathode guns can be used to provide pre-modulated electron beams, but have not yet been shown t The thermionic RF-gun has been widely used in FEL experiment. The main problem of thermionic RF-gun is electrons back bombardment. We express %( 2Q ) and ( ) * Q U P P ex c ( ), where is the external power dissipated, P is the power dissipated in cavity wall. Substituting these expressions into Eq. 2, we can ge

What's the speed of an electron accelerated through 5000V? An electron gun works by thermionic emission and particle acceleration. The Electron gun is esse.. Thermionic emission is the liberation of electrons from an electrode by virtue of its temperature (releasing of energy supplied by heat).This occurs because the thermal energy given to the charge carrier overcomes the work function of the material. The charge carriers can be electrons or ions, and in older literature are sometimes referred to as thermions Conventional thermionic microwave and radio frequency (RF) guns can offer high average beam current, which is important for synchrotron light and terahertz (THz) radiation source facilities, as well as for industrial applications. For example, the Advanced Photon Source at Argonne National Laboratory is a national synchrotron-radiation light source research facility that utilizes thermionic RF.

system has the advantages of maintainability, reliability, and stability over a photocathode radio-frequency (rf) gun because of its robust thermionic cathode. The basic performance of the injector prototype was confirmed at the SPring-8 compact self-amplified spontaneous emission source (SCSS) test accelerator Design of a simple electron gun Hawkes (2018) Fig. 43.1 •Cathode and extractor electrode •Heating causes electrons to come out •Not very efficient as heat of cathode is needed to change the electric current •Wehnelt (in 1903) introduced a third electrode that is held a negative potential with respect to the cathode. Low potential High potentia inexpensive thermionic gun is proposed instead of an rf photoinjector gun. The thermionic gun consists of a cathode-grid unit placed into a DESY-type 1 1/2 cell rf gun (Fig. 1) [2]. The gun design parameters are listed in Table I. Figure 1: DESY rf gun layout. The photocathode is to be replaced by the thermionic cathode-grid unit We present a novel concept for the generation of gigahertz repetition rate high brightness electron bunches. A custom design 100 kV thermionic gun provides a continuous electron beam, with the current determined by the filament size and temperature. A 1 GHz rectangular rf cavity deflects the beam across a knife-edge, creating a pulsed beam

Thermionic microwave gun for terahertz and synchrotron

The thermionic gun, is a triode type, EIMAC Y796. The electron current is controlled by Grid bias. To make a multi-bunchelectron beam with a bunch spac-ing of 2.8 ns, 357 MHz RF signal is applied to the GUN cathode. 357MHz ECL level RF signal is amplified by a power amplifier. This output has a pulse height of 400 V peak-to-peak, but the amplitude is gradually changing at the rise and fall. EXPECTED PERFORMANCE SUMMARY Today the extracted pulse length from the gun is on the The thermionic RF-gun at MAX-lab will be adapted to order of 100 ns but electrons are active causing beam operate as a photo RF-gun by using the existing BaO loading over a longer time. By using a 5 ns pulse from the cathode just below the thermal emission limit. A 5 ns laser the beam loading in the gun should be reduced by laser system at 355 nm will be able to produce a more 2395 Proceedings of EPAC 2004.

Conventional thermionic guns can offer high average beam current, which is necessary for synchrotron light and THz radiation sources facilities, as well as for industrial accelerators. Most of the light sources worldwide are storage ring based, and thus rely on thermionic guns for their operation. However, these devices are based on a decades-old thermionic RF gun designs that are due for a. Classes of Electron Guns and Injectors first injector specifically built for an fel was a gridded thermionic gun followed by stages of ballistic compressors to reduce the gun bunch length from 1 ns to 12 ps. The basic configuration is shown in the next slide. The injector was ~3 meters long to accommodate the components and drift lengths for compression. Typical gun voltages were between. Explanaition of an Electron Gun based on thermionic emission. The heater voltage V heat causes a current flow via the filament. This current heats the filament and because of the thermionic emission (thermal electron emission) electrons get out of the metal. So an electron cloud is set up around the hot cathode We present a novel concept for the generation of gigahertz repetition rate high brightness electron bunches. A custom design 100 kV thermionic gun provides a continuous electron beam, with the.

We developed an electron gun system capable of delivering high brightness beams to drive soft x-ray free-electron lasers (SXFEL). We modified the conventional radio-frequency (rf) gun concept by using a 50-kV gun with a gridded thermionic cathode connected with a 238-MHz acceleration cavity The Thermionic Effect is a process of generating a stream of electrons by raising a cathode to a high temperature causing it to emit electrons. In the case of the electron gun the cathode is heated in a vacuum and electrons from the cathode undergo thermionic emission It is charged negative and so the electric field focuses the electron beam in the middle. The glass tube is evacuated so the electrons do not interact with other particle or atoms. When filament voltage and acceleration voltage are on the electron gun generates a fine beam of fast electrons. This beam is not visible to the unaided eye This video is created by http://www.onlinetuition.com.my/More videos and free notes are available at http://spmphysics.onlinetuition.com.my A. Nassiri 100-MHz Thermionic RF Gun for ANL XFEL-O Injector FLS2010 -WG5 SLAC, March 2nd, 2010 5 Berkeley VHF Gun Design1  Staples, Sannibale, and colleagues have designed and developed an optimized 187 MHz rf gun at 750 kV with beam pulse rate to 1 MHz

thermionic gun. In the proposed scheme, the grid emittance arising from the potential difference between the grid and grid-mesh center is suppressed by tuning the grid voltage to the gridless gun potential. We developed a 50-kV gridded thermionic gun that is followed by a 238-MHz cavity for 500-kV acceleration. The measured pro CTF3 Thermionic Gun 16 Cathode Anode Insulator Cathode Grid Bucking Coil Pumping Port-140 kV A cathode + grid Disclaimer: These are not actual CTF3 systems Electron Current 5-10 A Electron Energy 140 keV Emittance 15-20 mm.mrad Pulse 1.4us @ 5 Hz Sintered tungsten dispenser cathode. Ohmic heating. 16mm diameter. Electron and Ion Sources CTF3 Thermionic Gun -bunching the beam 17 o The.

Ultrafast electron microscopes with thermionic guns and LaB6 sources can be operated in both the nanosecond, single-shot and femtosecond, single-electron modes. This has been demonstrated with conventional Wehnelt electrodes and absent any applied bias. Here, by conducting simulations using the General Particle Tracer code, we define the electron-gun parameter space within which various modes. LOW EMITTANCE THERMIONIC ELECTRON GUNS* - - W. B. HERRMANNSFELDT Stanford Linear Accelerator Center Stanford, California 94309 1. SELF FIELDS The beam emitted from the cathode of a well-designed electron gun is born with uniform current density. Almost by definition, this well-designed gun is a Piercer design with the focusing electrode carefully matched to the edge of the cathode.

How does the electron gun work? Thermionic Emission and

  1. thermionic gun driven by a pair of Avalanche Grid Pulsers (APG). The beam will be used for the study of a 1.5 Ge V linac . 3 ~tl . 19a.v dlv . Fig 7 Wave shale of double bunches . beam, Anode voltage: 150 kV, Heater voltage: 6.2 V, Net drive voltage: 286 V, Vacuum 2xl0-8 Torr . and a damping ring. Such a APG teclUlology will be useful for many thermionic gun applications. . In order to.
  2. A thermionic RF gun is compact in structure and is relatively simple to operate. It also can be operated at high repetition rates. Normally a diode or triode type thermionic electron gun is used. In a diode-type cathode, the high voltage is applied between the cathode and the anode to produce a CW electron beam. The electrons that fill the acceleration RF bucket are accelerated. The electrons.
  3. KEK-ATF is studying the low-emittance multi-bunch electron beam for the future linear collider. In ATF, thermionic gun is used to generate 20 bunches electron..
  4. Emissivity of Lanthanum Hexaboride Thermionic Electron Gun Cathode. International Journal of Thermophysics, 2014. Jeremy Kowalczy
  5. have used thermionic guns such as the Boeing [14], Stanford University [15,16], Novosibirsk [17], SPring-8 [18,19], and FELIX [20] FELs. These guns cannot be used for high average power IR FELs because of their low repetition rate. The first three examples were gridded guns, whose microbunch repetition rates were limited be- cause the grids were not directly driven with rf. The SPring-8 FEL.
  6. A thermionic microwave gun with a magnetic bunching system is comparable in cost and complexity to a conventional system, but provides performance that is orders of n1agnitude better. Simulations of the SSRL microwave gun predict a normalized RMS emittance at the gun exit of < 10.

Thermionic emission - Wikipedi

Thermionic Gun. Cathode Wehlnet cup Anode. Achieving Optimum Beam Current In general beam dia < 0.1 micron In SEM > we need small probe> no Wehnelt control is not provided In TEM> we may need brighter image> Wehnelt control is not provided. History of field emission • The basic mechanism of field emission was discovered in 1897 by Wood, who found that a high voltage applied between a pointed. Abstract. The emissivity of the thermionic electron gun cathode material lanthanum hexaboride (LaB \(_6\)) at an operating temperature of 1622 K has been measured for wavelengths from 550 nm to 2400 nm.The emissivity is calculated from scanning monochromator spectral measurements calibrated with a tungsten lamp and the published emissivity of 0.82 at 1600 K for LaB \(_6\) at 650 nm

Low-emittance thermionic-gun-based injector for a compact

The electron gun is based on a gridded thermionic cathode with the geometry based on a Pierce-type configuration. Both theory and numerical simulation were used to explore the relationship between the bunch length and the charge. The reasons for the pulse widening were also analyzed. The beam dynamics simulations showed that a minimum pulselength of 106 ps could be achieved with a bunch charge. Electron gun: Electron guns aren't some futuristic weapon used in the newest Vin Diesel movie. Instead, they produce the steady stream of electrons necessary for SEMs to operate. Electron guns are typically one of two types. Thermionic guns, which are the most common type, apply thermal energy to a filament (usually made of tungsten, which has a high melting point) to coax electrons away from. A high gradient, S-band microwave gun with a thermionic cathode is being developed in a collaborative effort by AET, Varian, and SSRL. A prototype design using an upgraded Varian dispenser cathode mounted with thermal isolation directly in the first half-cell of a 1-1/2 cell, side coupled, standing-wave cavity was fabricated and is being tested

Gigahertz repetition rate thermionic electron gun concep

A low-emittance thermionic-gun-based injector was developed for the x-ray free-electron laser (XFEL) facility known as the SPring-8 angstrom compact free-electron laser (SACLA). The thermionic-gun-based system has the advantages of maintainability, reliability, and stability over a photocathode radio-frequency (rf) gun because of its robust thermionic cathode BackgroundHigh brightness X-ray light sources are now making the transition from research laboratories into industry, where reliability and cost become important parameters. State-of-the-art high average current pulsed electron sources use semiconductor photocathodes that require ultra-high vacuum, a high power laser system and have limited cathode lifetime

(Pdf) Adaption of An Rf-gun From Thermionic to Photo

  1. thermionic RF guns are still expected to have potential ability to create high-brightness and short-pulse beams [1]. In particular, whole system of the thermionic RF gun is simple, compact and low-cost than that of a photo-cathode RF gun. In addition, a velocity-bunching like effect may be occurred in the gun, so that the short pulse beam from the thermionic RF gun is a better candidate to.
  2. Thermionic RF guns are used as highly brilliant electron source for linac-driven FEL (free electron laser). They can potentially produce an electron beam with high energy, small emittance, short pulse duration, inexpensive and compact configuration in comparison with other high brightness electron sources, e.g., DC guns and photocathode RF guns. The most critical issue of the thermionic RF gun.
  3. ary operation of the gun.

Electron Gun The electron gun produces an electron beam. Its con-struction is shown in Fig. 2. Note that this is a thermionic emission gun (TE gun). Thermoelectrons are emitted from a filament (cathode) made of a thin tungsten wire (about 0.1 mm) by heating the filament at high temperature (about 2800K). These thermoelectrons are gathered as a A thermionic heater cathode assembly for an electron-beam gun, comprising a disc cathode made of a highly-emissive material and disposed near a metal ribbon filament the thermionic portion whereof has a W shape, the distance between two apices of said thermionic portion being 0.6 to 0.8 of the disc cathode diameter and the depth of the valley between the apices constituting 0.5 to 0.6 of said. KEK-ATF is studying the low-emittance multi-bunch electron beam for the future linear collider. In ATF, thermionic gun is used to generate 20 bunches electron beam with the bunch spacing of 2.8 ns. Due to a distortion of the gun emission and the beam loading effect in the bunching system, the intensity for each bunch is not uniform by up to 40 % at the end of the injector An electron gun comprises a linear thermionic cathode having part of its emitting surface facing an accelerating anode, and the rest of the emitting surface separated by a gap from a cathode-adjacent focusing electrode. The cathode-adjacent focusing electrode is made of two portions spaced apart. On the opposite end surfaces of these portions, there is attached a pair of flat current. The zirconia lowers the work function of the tungsten and can use the broader tip . Unlike the thermionic gun, the FEG does not produce a small cross-over directly below the emitter, but the electron trajectories seemingly originate inside the tip itself, forming a virtual source of electrons for the microscope. 31

SEM,TEM & AFM

Thermionic emission • If we heat any material to a high enough temperature, we can give the electrons sufficient energy to overcome the work function (Φ) which usuallyhasavalueof afeweV. • The thermionic emission is well explained by Richardson'sLaw in terms of thecurrentdensity(J)fromthesource. J = AT 2e-Φ/k Thermionic guns with relatively low energy are common in a number commercial applications - Electron beam welding - Electron beam heating - Electron beam evaporation • These require 0.1 to 1 A, and generally operate at tens of kW - Electron beam lithography - Cathode ray tubes Several research techniques

(PDF) Low-emittance radio-frequency electron gun using a

  1. Electron guns are frequently used in cathode ray tubes, electron microscopes, spectrometers, and particle accelerators. The electron gun extracts electrons from a hot cathode or a plasma, then accelerates them to a high kinetic energy. One of the main design challenges in building an electron gun is that the electrons repel each other, so the beam tends to spread out. Here, we discuss modeling.
  2. A thermionic Gun for the drive beam generation 2. A test photo-emission and RF gun as a test facility for the drive beam. 3. A photo-emission and RF gun for the probe beam. Electron and Ion Sources CLIC Drive Beam Thermionic Gun 15 Cathode System Cathode Test Stand The CLIC Drive Beam Electron Gun is a Thermonic Gun. Electron and Ion Sources CTF3 Thermionic Gun -bunching the beam 16 o The.
  3. ation aperture •Increase wavelength •Stability -High voltage supply -Current: •Thermionic/Schottky - stable ~ ± 1%/hr •CFE < ± 5%/hr -FE: Better UHV •Life/Cos

Thermionic electron radio frequency (RF) guns are cost e ective and simple in operation electron sources which are used for Free Electron Laser (FEL) facilities. The performance of the FEL is determined by the quality of the electron beam produced by the RF gun. In this research the feasibility of improvement of performance of thermionic RF gun was studied as proof of principles based on two. Although photoinjetcors using RF guns are rapidly developped as high blliiant electron sources, while thermionic RF guns are still expected to have potential ability to create high-brightness and short-pulse beams [1]. In particular, components of a thermionic RF gun are simple, compact and low-cost than those of a photo-cathode RF gun. For creating such beams, a prototype of thermionic RF gun. CID THERMIONIC GUN SYSTEM* By R. F. Koontz. Abstract. A new high-current thermion-ic gun has been installed on the CID injector at SLAC and brought into operation. The gun and pulser system generate three nano-second pulses of about six amps peak which, when bunched in the subharmonic buncher system, produce in excess of 1011 electrons in a single S-band accelerated bunch. Preliminary.

PAPER OPEN ACCESS Microwave thermionic electron gun for

  1. The best pure metal thermionic emitter is tungsten which has a work function of 4.54 eV which at 1500K can provide 1.5 × 10 −7 A/cm 2.Modern microwave tubes operate with cathode loadings of 1 to 8 A/cm 2, so we can see how inadequate pure metal emitters are.. The oxide cathode has been the mainstay of the receiving tube designs for many decades
  2. thermionic DC-rf gun, in this paper we present a detailed design study of a CW normal conducting thermionic rf gun with a dispersion-free configuration of the cathode-gate-electrode region. Given that a two-conductor transmission line allows dispersion-free propagation of transverse electromagnetic(TEM)-modes,ourideais tousea stripline with a thermionic cathode integrated into it so that we.
  3. ation
  4. PROJECT TITLE: Machine learning for nucleon structure studies. PROJECT MENTOR: Dr. Wally Melnitchouk (wmelnitc@jlab.org)PROJECT DESCRIPTION: The goal of this project is to build the next generation of global QCD analysis tools using machine learning (ML) techniques to study quantum probability distributions, such as parton distribution functions (PDFs) and transverse momentum dependent.
  5. We describe use of the Advanced Photon Source (APS) rf thermionic gun, alpha magnet beamline, and linac to produce a stable high-brightness beam in excess of..

Thermionics - an overview ScienceDirect Topic

Gridded thermionic gun and integral superconducting

Function of an Electron Gun

(PDF) Gigahertz repetition rate thermionic electron gun

Electron Source (GUN)

Low-emittance radio-frequency electron gun using a gridded

  1. Thermionic Emission 105 l b anode cathode: hot filament, radius a anode cathode 1 4 2 Figure 5.2: Coaxial cylinders: an inner wire (radius a) and outer cylindrical anode (radius b), form a vacuum tube diode. The cathode is heated so electron evaporation is possible, and a potential difference V A attracts electrons from the cathode to the anode. The speed of the electrons v(r) increases as.
  2. In ATF, thermionic gun is used to generate 20 bunches electron beam with the bunch spacing of 2.8 ns. Due to a distortion of the gun emission and the beam loading effect in the bunching system, the intensity for each bunch is not uniform by up to 40 % at the end of the injector. We have developed a system to correct the gun emission by precisely controlling the cathode voltage with a function.
  3. Compared to general thermionic electron guns (heats metals, etc., to draw out electrons), it generates an electron beam of about one-thousand-times brighter. Related Links Achieved 3×10 14 A/m 2 sr - the world's highest recorded brightness - using the Atomic-Resolution Holography Electron Microscop
  4. ates the specimen. Relatively weak lens. Longer focal length than objective.
  5. thermionic cathode gun sound ,thermionic cathode gun pronunciation, how to pronounce thermionic cathode gun, click to play the pronunciation audio of thermionic cathode gun
Schottky emission electron gunsTransmission Electron MicroscopeElectricity - Cathode Ray OscilloscopeComponents in a SEM - Nanoscience InstrumentsTask to label parts of an electron gun with correctKimball Lanthanum Hexaboride Cathodes for Electron MicroscopesUCSB FEL ELECTRON GUNS

Stanford Libraries' official online search tool for books, media, journals, databases, government documents and more Marc E. Hemiter, A Bombardment Heated LaB6 Thermionic Cathode Electron Gun, Department of Electrical Engineering and Computer Science, The University of Michigan, Ann Arbor, 1989. (Abstract in Appendix Gun tilt: For the thermionic emitters, gun tilt is most simply set by viewing the SEM image and adjusting the gun tilt controls until the highest image brightness is obtained. Some SEM manufacturers will also have special scan modes so that the gun tilt can be adjusted in a manor analogous to in a TEM, but the 'brightest image' criterion will always work, and in many cases is simpler. Field.

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