RECENT STRUCTURE BASED HIGH GRADIENT WAKEFIELD EXPERIMENTS AT ARGONNE

2007 ◽  
Vol 21 (03n04) ◽  
pp. 372-377
Author(s):  
W. GAI ◽  
M. E. CONDE ◽  
F. GAO ◽  
C. JING ◽  
R. KONECNY ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Electron Beam ◽  
Output Coupler ◽  
High Field ◽  
Bunch Length ◽  
Accelerator Facility ◽  
Dielectric Tube ◽  
Electron Bunches ◽  
Dielectric Structures ◽  
Wakefield Accelerator

Dielectric structures promise to support high field, especially for short wakefield pulses produced by a high charged electron beam traveling in a dielectric tube. To push the gradient higher, we have tested two structures using recent upgraded Argonne wakefield accelerator facility that capable of producing up to 100 nC charge and bunch length of < 13 ps (FWHM). Here we report on the experiment results that more than 80 nC beam passes through a 14 GHz dielectric loaded wakefield structure that produced an accelerating field of ~ 45 MV/m . The two structures consist of a cylindrical ceramic tube (cordierite) with a dielectric constant of 5, inner and outer radii of 5 mm and 7.49 mm, respectively, and with length of 102 mm and 23 mm long. We present measurements made with single electron bunches and also with two bunches separated by 1.5 ns. As a next step in these experiments, another structure, with an output coupler, has been designed and is presently being fabricated.

scholarly journals ACCELERATING OF THE ELECTRONS OF ELECTRON BUNCHES IN A WAVEGUIDE LOADED DIELECTRIC STRUCTURE

2021 ◽  
pp. 67-71
Author(s):  
A.F. Linnik ◽  
I.N. Onishchenko ◽  
O.L. Omelayenko ◽  
V.I. Pristupa ◽  
G.V. Sotnikov ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Bunch Length ◽  
Dielectric Structure ◽  
Steady State Mode ◽  
Electron Bunches ◽  
Simple Physical Model ◽  
Wake Wave ◽  
The Difference ◽  
Wake Fields ◽  
Dielectric Structures

The paper presents some results of experimental studies of the excitation of wake fields and the acceleration of electrons in waveguide-dielectric structures (DS) upon injection of a sequence of electron bunches into them. Exper-iments have shown an increase in the amplitude of the wake wave and the acceleration of a small fraction of elec-trons when the wavelength of the excited field is equal to the doubled bunch length. A simple physical model of the observed phenomenon is given. Also, the paper proposes a method for accelerating a part of each electron bunch in the steady-state mode of the resonator dielectric structure. Some of the electrons are “cut out” by the collimator and enter the accelerating phase of the previously excited wake wave. The wave is displaced due to the difference in the distances traveled by the wave and the accelerated part of the electrons.

High resolution electron beam measurements on the ALPHA-X laser–plasma wakefield accelerator

2012 ◽  
Vol 78 (4) ◽  
pp. 393-399 ◽  
Author(s):  
G. H. WELSH ◽  
S. M. WIGGINS ◽  
R. C. ISSAC ◽  
E. BRUNETTI ◽  
G. G. MANAHAN ◽  
...  
Keyword(s):  
Electron Beam ◽  
High Resolution ◽  
Laser Plasma ◽  
Electron Bunch ◽  
High Energy ◽  
Energy Spread ◽  
Gas Jet ◽  
X Rays ◽  
Electron Bunches ◽  
Wakefield Accelerator

AbstractThe Advanced Laser–Plasma High-Energy Accelerators towards X-rays (ALPHA-X) programme at the University of Strathclyde is developing laser–plasma accelerators for the production of ultra-short high quality electron bunches. Focussing such LWFA bunches into an undulator, for example, requires particular attention to be paid to the emittance, electron bunch duration and energy spread. On the ALPHA-X wakefield accelerator beam line, a high intensity ultra-short pulse from a 30 TW Ti:Sapphire laser is focussed into a helium gas jet to produce femtosecond duration electron bunches in the range of 90–220 MeV. Measurements of the electron energy spectrum, obtained using a high resolution magnetic dipole spectrometer, show electron bunch r.m.s. energy spreads down to 0.5%. A pepper-pot mask is used to obtain transverse emittance measurements of a 128 ± 3 MeV mono-energetic electron beam. An average normalized emittance of ϵrms,x,y = 2.2 ± 0.7, 2.3 ± 0.6 π-mm-mrad is measured, which is comparable to that of a conventional radio-frequency accelerator. The best measured emittance of ϵrms,x, = 1.1 ± 0.1 π-mm-mrad corresponds to the resolution limit of the detection system. 3D particle-in-cell simulations of the ALPHA-X accelerator partially replicate the generation of low emittance, low energy spread bunches with charge less than 4 pC and gas flow simulations indicate both long density ramps and shock formation in the gas jet nozzle.

Radiation Production Using Femtosecond Electron Bunches

2005 ◽  
Vol 107 ◽  
pp. 11-14
Author(s):  
C. Thongbai ◽  
V. Jinamoon ◽  
N. Kangrang ◽  
K. Kusoljariyakul ◽  
S. Rimjaem ◽  
...  
Keyword(s):  
Far Infrared ◽  
Bunch Length ◽  
X Rays ◽  
Research Facility ◽  
X Ray ◽  
Electron Bunches ◽  
Rf Gun ◽  
Intense Radiation ◽  
Far Infrared Radiation ◽  
Femtosecond Electron Bunches

Femtosecond electron bunches can be generated from a system consisting of an RF gun with a thermionic cathode, an alpha magnet, and a linear accelerator and can be used to produce femtosecond (fs) electromagnetic radiation pulses. At the Fast Neutron Research Facility (FNRF), Thailand, we are especially interested in production in Far-infrared (FIR) and x-radiation. In the far-infrared, radiation is emitted coherently for wavelengths which are longer than the electron bunch length, yielding intense radiation. Although, the x-rays emitted are incoherent, its femtosecond time scale is crucial for development of a femtosecond x-ray source.

scholarly journals Manipulation of Laser Distribution to Mitigate the Space-Charge Effect for Improving the Performance of a THz Coherent Undulator Radiation Source

Particles ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 238-252 ◽  
Author(s):  
Siriwan Krainara ◽  
Shuya Chatani ◽  
Heishun Zen ◽  
Toshiteru Kii ◽  
Hideaki Ohgaki
Keyword(s):  
Electron Beam ◽  
Space Charge ◽  
Electron Bunch ◽  
Beam Quality ◽  
Space Charge Effect ◽  
Bunch Length ◽  
Charge Effect ◽  
Simulation Code ◽  
Undulator Radiation ◽  
Radiated Power

A THz coherent undulator radiation (THz-CUR) source has been developed at the Institute of Advanced Energy, Kyoto University. A photocathode Radio-Frequency (RF) gun and a bunch compressor chicane are used for generating short-bunch electron beams. When the electron beam energy is low, the space-charge effect strongly degrades the beam quality, such as the bunch length and the energy spread at the high bunch charge condition at around 160 pC, and results in the reduction of the highest frequency and the maximum radiated power of the THz-CUR. To mitigate the space charge effect, we have investigated the dependence of the electron beam quality on the laser distribution in transverse and longitudinal directions by using a numerical simulation code, General Particle Tracer GPT. The manipulation of the laser distribution has potential for improving the performance of the THz-CUR source. The electron bunch was effectively compressed with the chicane magnet when the laser transverse distribution was the truncated Gaussian profile, illuminating a cathode. Moreover, the compressed electron bunch was shortened by enlarging the laser pulse width. Consequently, an enhancement of the radiated power of the THz-CUR has been indicated.

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