FEL2015 - List of Keywords (target)

Paper	Title	Other Keywords	Page
TUP079	Laser Wakefield Acceleration by using a Laser Produced Aluminium Plasma	plasma, laser, electron, acceleration	543
	J. Kim, Y.H. Hwangbo, S.G. Jeon KERI, Changwon, Republic of Korea K.N. Kim, S. H. Park, W.J. Ryu, N. Vinokurov KAERI, Daejon, Republic of Korea
	In laser wakefield accelerator, usually a gas target is used to generate plasma medium. With this gas target, the pressure of the system cannot be keep as low as possible for electron beam application such as seeding the storage ring. To reduce this vacuum problem in LWFA, a plasma generated from solid Al target was used as plasma medium. A fundamental beam from the Q-switched ns pump laser in the Ti:sapphire power amplifier was used to generate a plasma from solid Al target. The plasma density was controlled by changing the distance between the main laser pulse for electron acceleration and the solid target. The plasma density was measured by the interferometer. The measured density indicates that the average charge of the ion in pre-plasma was 4.4. The main pulse ionized the Al plasma up to Al XII which means that the ionization injection could be used as an injection scheme. A 28 TW fs laser was used to accelerate the electron. A quasi-monochromatic electron was generated. The peak energy was 70 MeV and energy spread was 15 %. The divergence of the beam was 12 mrad in horizontal direction and 6 mrad in vertical direction.
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TUD02	Diffraction Radiation Monitor	electron, radiation, beam-diagnostic, diagnostics	561
	Y. Taira AIST, Tsukuba, Japan
	Non-invasive beam diagnostics using a diffraction radiation (DR) has been developed at several electron accelerator facilities. Generation process of DR is similar to that of transition radiation (TR). TR is emitted when a charged particle passes through the boundary between two media with different dielectric constants. On the other hand, DR is emitted when it passes through in the vicinity of a boundary between two media. In the generation process of DR, the charged particle doesn't intersect the medium but its electric field intersects the medium. An aperture, a slit, and an edge are used for DR target. Optical wavelength of DR is usually used for beam diagnostics. One can evaluate energy, a transverse beam size, and a divergence of an electron beam by measuring a spatial distribution of DR. Moreover, coherent diffraction radiation with the wavelength of less than millimeter range is used for a bunch length measurement. In this conference, a theoretical background of DR and experimental results carried out at several facilities will be presented.
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WEP042	Commissioning and First Performance of the LINAC-based Injector Applied in the HUST THz-FEL	linac, FEL, gun, beam-diagnostic	662
	T. Hu, Q.S. Chen, J. Li, B. Qin, P. Tan, Y.Q. Xiong HUST, Wuhan, People's Republic of China L. Cao, W. Chen Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People's Republic of China Y.J. Pei, Zh. X. Tang USTC/NSRL, Hefei, Anhui, People's Republic of China
	The construction of a compact high-power THz source based on the free electron laser(FEL), which is constructed in HUST, is undergoing. Before the end of 2014, we have installed most of the key components, completed conditioning of the LINAC-based FEL injector, and performed first beam experiment. During last 5 months, we have established a high efficient beam diagnostic system with a reliable online monitor platform and precise data processing methods. At present, longitudinal properties such as the micro-pulse width and the energy spread are kept to a reasonable level, while transverse emittance compensation by adjusting focusing parameters is still undergoing. In this paper, we will give the summary on the commissioning schedule, detailed commissioning plan, the development of the commissioning and first performance of the LINAC, etc.
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WEP079	Inclusion of Advanced Fields and Boundary Conditions in the Analytic Theory for High Gain FELs	FEL, electron, radiation, undulator	735
	P. Niknejadi, J. Madey University of Hawaii, Honolulu,, USA
	The efforts in realizing x-ray free electron lasers (FELs) and enhancing their performance has stimulated remarkable theoretical developments and experimental advances in the field. Yet, the successful operation of x-ray FELs based on the self-amplified spontaneous emission (SASE) principle which has made them a powerful new tool, has beckoned our attention for better understanding a comprehensive physical basis of the theory that has the potential to improve the temporal structure and spectral optimization of these sources. We have previously explained the advantages of including the coherent radiation reaction force as a part of the solution to the boundary value problem for FELs that radiate into "free space" (SASE FELs) and discussed how the advanced field of the absorber can interact with the radiating particles at the time of emission.(, ) Here we present the outline of our theoretical approach which follows from eigenmode analysis of optical guiding in FELs. We will also discuss in some detail the experimental setup that could verify and/or further our understanding of the the underlying physics of these devices. P. Niknejadi et al., Phys. Rev. D 91 096006 (2015) ** P. Niknejadi and J.M.J. Madey, in Proceedings of Free Electron Laser Conference, JACoW, Basel, Switzerland (2014)
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WEP087	Smith-Purcell Radiation from Microbunched Beams Modulated after Passing the Undulators in FELs	radiation, FEL, undulator, polarization	752
	A. Potylitsyn TPU, Tomsk, Russia D.Yu. Sergeeva, M.N. Strikhanov, A.A. Tishchenko MEPhI, Moscow, Russia
	We suggest using the Smith-Purcell effect from microbunched beams modulated after passing the undulators in FELs as an extra source of monochromatic radiation. We investigate theoretically characteristics of Smith-Purcell radiation in THz and X-ray frequency regions for two types of distribution of the particles in the beam. The expression for spectral-angular distribution of such radiation is obtained and analyzed, both for fully and partially modulated beams. The intensity of Smith-Purcell radiation is shown to be able to increase both due to the periodicity of the beam and the periodicity of the target. The numerical results prove that such radiation source can be an effective instrument for different FEL users, supplementary for the main FEL source.
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Paper

Title

Other Keywords

Page

TUP079

Laser Wakefield Acceleration by using a Laser Produced Aluminium Plasma

plasma, laser, electron, acceleration

543

J. Kim, Y.H. Hwangbo, S.G. Jeon
KERI, Changwon, Republic of Korea
K.N. Kim, S. H. Park, W.J. Ryu, N. Vinokurov
KAERI, Daejon, Republic of Korea

In laser wakefield accelerator, usually a gas target is used to generate plasma medium. With this gas target, the pressure of the system cannot be keep as low as possible for electron beam application such as seeding the storage ring. To reduce this vacuum problem in LWFA, a plasma generated from solid Al target was used as plasma medium. A fundamental beam from the Q-switched ns pump laser in the Ti:sapphire power amplifier was used to generate a plasma from solid Al target. The plasma density was controlled by changing the distance between the main laser pulse for electron acceleration and the solid target. The plasma density was measured by the interferometer. The measured density indicates that the average charge of the ion in pre-plasma was 4.4. The main pulse ionized the Al plasma up to Al XII which means that the ionization injection could be used as an injection scheme. A 28 TW fs laser was used to accelerate the electron. A quasi-monochromatic electron was generated. The peak energy was 70 MeV and energy spread was 15 %. The divergence of the beam was 12 mrad in horizontal direction and 6 mrad in vertical direction.

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TUD02

Diffraction Radiation Monitor

electron, radiation, beam-diagnostic, diagnostics

561

Y. Taira
AIST, Tsukuba, Japan

Non-invasive beam diagnostics using a diffraction radiation (DR) has been developed at several electron accelerator facilities. Generation process of DR is similar to that of transition radiation (TR). TR is emitted when a charged particle passes through the boundary between two media with different dielectric constants. On the other hand, DR is emitted when it passes through in the vicinity of a boundary between two media. In the generation process of DR, the charged particle doesn't intersect the medium but its electric field intersects the medium. An aperture, a slit, and an edge are used for DR target. Optical wavelength of DR is usually used for beam diagnostics. One can evaluate energy, a transverse beam size, and a divergence of an electron beam by measuring a spatial distribution of DR. Moreover, coherent diffraction radiation with the wavelength of less than millimeter range is used for a bunch length measurement. In this conference, a theoretical background of DR and experimental results carried out at several facilities will be presented.

Export •

reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

WEP042

Commissioning and First Performance of the LINAC-based Injector Applied in the HUST THz-FEL

linac, FEL, gun, beam-diagnostic

662

T. Hu, Q.S. Chen, J. Li, B. Qin, P. Tan, Y.Q. Xiong
HUST, Wuhan, People's Republic of China
L. Cao, W. Chen
Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People's Republic of China
Y.J. Pei, Zh. X. Tang
USTC/NSRL, Hefei, Anhui, People's Republic of China

The construction of a compact high-power THz source based on the free electron laser(FEL), which is constructed in HUST, is undergoing. Before the end of 2014, we have installed most of the key components, completed conditioning of the LINAC-based FEL injector, and performed first beam experiment. During last 5 months, we have established a high efficient beam diagnostic system with a reliable online monitor platform and precise data processing methods. At present, longitudinal properties such as the micro-pulse width and the energy spread are kept to a reasonable level, while transverse emittance compensation by adjusting focusing parameters is still undergoing. In this paper, we will give the summary on the commissioning schedule, detailed commissioning plan, the development of the commissioning and first performance of the LINAC, etc.

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reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

WEP079

Inclusion of Advanced Fields and Boundary Conditions in the Analytic Theory for High Gain FELs

FEL, electron, radiation, undulator

735

P. Niknejadi, J. Madey
University of Hawaii, Honolulu,, USA

The efforts in realizing x-ray free electron lasers (FELs) and enhancing their performance has stimulated remarkable theoretical developments and experimental advances in the field. Yet, the successful operation of x-ray FELs based on the self-amplified spontaneous emission (SASE) principle which has made them a powerful new tool, has beckoned our attention for better understanding a comprehensive physical basis of the theory that has the potential to improve the temporal structure and spectral optimization of these sources. We have previously explained the advantages of including the coherent radiation reaction force as a part of the solution to the boundary value problem for FELs that radiate into "free space" (SASE FELs) and discussed how the advanced field of the absorber can interact with the radiating particles at the time of emission.(*, **) Here we present the outline of our theoretical approach which follows from eigenmode analysis of optical guiding in FELs. We will also discuss in some detail the experimental setup that could verify and/or further our understanding of the the underlying physics of these devices.
* P. Niknejadi et al., Phys. Rev. D 91 096006 (2015)
** P. Niknejadi and J.M.J. Madey, in Proceedings of Free Electron Laser Conference, JACoW, Basel, Switzerland (2014)

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WEP087

Smith-Purcell Radiation from Microbunched Beams Modulated after Passing the Undulators in FELs

radiation, FEL, undulator, polarization

752

A. Potylitsyn
TPU, Tomsk, Russia
D.Yu. Sergeeva, M.N. Strikhanov, A.A. Tishchenko
MEPhI, Moscow, Russia

We suggest using the Smith-Purcell effect from microbunched beams modulated after passing the undulators in FELs as an extra source of monochromatic radiation. We investigate theoretically characteristics of Smith-Purcell radiation in THz and X-ray frequency regions for two types of distribution of the particles in the beam. The expression for spectral-angular distribution of such radiation is obtained and analyzed, both for fully and partially modulated beams. The intensity of Smith-Purcell radiation is shown to be able to increase both due to the periodicity of the beam and the periodicity of the target. The numerical results prove that such radiation source can be an effective instrument for different FEL users, supplementary for the main FEL source.

Export •

reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)