FEL2013 - List of Keywords (acceleration)

Paper	Title	Other Keywords	Page
MOPSO34	Highly Efficient, High-energy THz Pulses from Cryo-cooled Lithium Niobate for Accelerator and FEL Applications	electron, laser, cryogenics, FEL	68
	K.-H. Hong, E. Granados, S.-W. Huang, W.R. Huang, F.X. Kaertner, R. Koustuban, L.E. Zapata MIT, Cambridge, Massachusetts, USA F.X. Kaertner CFEL, Hamburg, Germany
	Funding: This work was supported by DARPA under contract N66001-1-11-4192. Intense, ultrafast THz fields are of great interest for electron acceleration, beam manipulation and measurement, and pump-probe experiments with coherent soft/hard x-ray sources based on FELs or inverse Compton scattering sources. Acceleration at THz frequencies has an advantage over RF in terms of accessing high electric-field gradients (>100 MV/cm), while the beam delivery can be treated quasi-optically. However, high-field THz pulse generation is still demanding when compared with conventional RF generation. In this paper, we present highly efficient, single-cycle, 0.45 THz pulse generation by optical rectification of 1.03 μm pulses in cryogenically cooled lithium niobate (LN). Using a near-optimal duration of 680 fs and a pump energy of 1.2 mJ, we report conversion efficiencies above 3% [1], >10 times higher than previous report (0.24%) [2]. Cryogenic cooling of lithium niobate significantly reduces the THz absorption, which will enable the scaling of THz pulse energies to the mJ. We will also report on polarization and mode conversion using segmented THz waveplates to generate radially-polarized TEM01 modes, suitable for THz electron acceleration in dielectric waveguide. [1] S.-W. Huang et al., Opt. Lett. 38, 796-798 (2013). [2] J. A. Fülöp et al., Opt. Lett. 37, 557-559 (2012).

MOPSO70	Crystal Channeling Acceleration Research for High Energy Linear Collider at ASTA Facility	electron, plasma, radiation, laser	122
	Y.-M. Shin Northern Illinois University, DeKalb, Illinois, USA K. Carlson, M.D. Church, V.D. Shiltsev, D.A. Still Fermilab, Batavia, USA J.C. Tobin UMD, College Park, Maryland, USA
	The density of charge carriers in solids is significantly higher than what was considered above in plasma, and correspondingly, the longitudinal fields of up to 10 TV/m are possible. It was suggested that particles are accelerated along major crystallographic directions, which provide a channeling effect in combination with low emittance determined by an Angstrom-scale aperture of the atomic “tubes.” However, the major challenge of this channeling acceleration is that ultimate acceleration gradients might require relativistic intensities at hard x-ray regime (~ 40 keV), exceeding those conceivable for x-rays as of today, though x-ray lasers can efficiently excite solid plasma and accelerate particles inside a crystal channel. However, the acceleration will take place only in a short time before full dissociation of the lattice. Carbon nanotubes have great potential with a wide range of flexibility and superior physical strength, which can be applied to channeling acceleration and possibly fast cooling. This talk will present past and current efforts on crystal acceleration research and discuss feasible experiments with the ASTA and beyond.

TUOCNO03	Progress in a Photocathode DC Gun at the Compact ERL	gun, vacuum, cathode, high-voltage	184
	N. Nishimori, R. Hajima, S.M. Matsuba, R. Nagai JAEA, Ibaraki-ken, Japan Y. Honda, T. Miyajima, M. Yamamoto KEK, Ibaraki, Japan H. Iijima, M. Kuriki HU/AdSM, Higashi-Hiroshima, Japan M. Kuwahara Nagoya University, Nagoya, Japan
	Photocathode DC gun to produce a train of electron bunch at high-average current and small emittance is a key component of advanced accelerators for high-power beams. However, DC guns operated at a voltage above 350 kV have suffered from field emitted electrons from a support rod since the development of Lasertron in 1980's. This critical issue has been resolved by a novel configuration, segmented insulator and guard rings, adopted in a DC gun at JAEA and stable application of high voltage at 550 kV has been demonstrated. The gun has been installed at the Compact ERL at KEK and ready for the beam generation. Similar type of DC guns are under development at KEK, Cornell, JLAB and IHEP. In this talk, we present progress in photocathode DC gun for high voltage and small emittance.
	Slides TUOCNO03 [4.946 MB]

TUPSO18	Optimization of Dielectric Loaded Metal Waveguides for Acceleration of Electron Bunches using Short THz Pulses	electron, space-charge, laser, emittance	250
	A. Fallahi, F.X. Kaertner CFEL, Hamburg, Germany F.X. Kaertner, A. Sell, L.J. Wong MIT, Cambridge, Massachusetts, USA
	Funding: DARPA contract number N66001-11-1-4192 and the Center for Free-Electron Laser Science, DESY Hamburg The last decade has witnessed extensive research efforts to reduce the size of charged particle accelerators to achieve compact devices for providing relativistic particles. To this end, various methods such as laser plasma and dielectric wakefield acceleration are investigated and their pros and cons are studied. With the advent of efficient THz generation techniques based on optical rectification, THz waveguides are also considered to be proper candidates for compact accelerators. Sofar, the proposed schemes toward high power THz generation are capable of producing short pulses, which dictates the study of particle acceleration in the pulsed regime rather than continuous-wave regime. Therefore, THz waveguides are more suitable than cavities for the considered purpose. Consequently, various effects such as group velocity mismatch and group velocity dispersion start to influence the acceleration scenario and impose limits on the maximum energy gain from the pulse. In this contribution, we investigate electron bunch acceleration and compression in dielectrically loaded metal waveguides for the THz wavelength range and present design methodologies to optimize their performance. Liang Jie Wong, Arya Fallahi, and Franz X. Kärtner. "Compact electron acceleration and bunch compression in THz waveguides." Optics Express 21, no. 8 (2013): 9792-9806.

TUPSO46	Analysis and Measurement of Focusing Effects in a Traveling Wave Linear Accelerator	quadrupole, focusing, electron, simulation	329
	H. Maesaka, T. Asaka, H. Ego, T. Hara, T. Inagaki, Y. Otake, T. Sakurai, H. Tanaka, K. Togawa RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	We propose a further precise model of the transverse dynamics in a traveling wave linear accelerator (TWA) and report experimental results to demonstrate the validity of the model. In SACLA, the beam orbit is calculated by using a transfer matrix based on the transverse dynamics model of each component and the matrix is utilized for orbit stabilization, beam envelop matching etc. For the TWA part, a transfer matrix including an emittance damping effect and an edge focusing effect [] is employed. However, the beam orbit measured by rf cavity beam position monitors (RF-BPM) [] did not agree with the calculated orbit, especially for the off-crest acceleration part. Therefore, focusing effects in a TWA structure were analyzed by using a 3-dimensional rf simulation code. The analysis indicated that the transverse dynamics model of the TWA should include an additional quadrupole edge focusing effect. The amount of the additional focusing effect of the TWA was measured in SACLA and the rf simulation result was confirmed to be consistent with the measurement. After the modification of the transverse dynamics model, the beam orbit measured by RF-BPM agrees with the calculation. T. Hara et al., Nucl. Instrum. Methods A 624, 65 (2010). ** H. Maesaka et al., Nucl. Instrum. Methods A 696, 66 (2012).

TUPSO59	Study of a Photocathode-based Microtron using a PIC Code	electron, microtron, laser, injection	363
	S. Park Kyungpook National University, Daegu, Republic of Korea K.H. Jang, Y.U. Jeong, S. H. Park, N. Vinokurov KAERI, Daejon, Republic of Korea E.-S. Kim KNU, Deagu, Republic of Korea N. Vinokurov BINP SB RAS, Novosibirsk, Russia
	Korea Atomic Energy Research Institute (KAERI) has used thermionic cathode-based microtron accelerator for operating compact THz FEL due to its compact size and high energy resolution. In this thermionic cathode-based microtron, rightly phased electron bunch train are automatically accelerated during the RF macro-pulse over threshold power for their emission. But, the thermionic cathode should be replaced with a photocathode for applying the microtron to UED or THz/X-ray pump prove experiment requiring femto-second and high peak current. But, it is needed to analyze precisely the electron beam dynamics in a microtron, especially, the relation between the RF phase in a microtron cavity and Laser input time for adapting the photocathode to a microtron. Hence, we conduct computer simulation with 3D PIC-code to find those optimized conditions for operating photocathode-based microtron.

Paper

Title

Other Keywords

Page

MOPSO34

Highly Efficient, High-energy THz Pulses from Cryo-cooled Lithium Niobate for Accelerator and FEL Applications

electron, laser, cryogenics, FEL

68

K.-H. Hong, E. Granados, S.-W. Huang, W.R. Huang, F.X. Kaertner, R. Koustuban, L.E. Zapata
MIT, Cambridge, Massachusetts, USA
F.X. Kaertner
CFEL, Hamburg, Germany

Funding: This work was supported by DARPA under contract N66001-1-11-4192.
Intense, ultrafast THz fields are of great interest for electron acceleration, beam manipulation and measurement, and pump-probe experiments with coherent soft/hard x-ray sources based on FELs or inverse Compton scattering sources. Acceleration at THz frequencies has an advantage over RF in terms of accessing high electric-field gradients (>100 MV/cm), while the beam delivery can be treated quasi-optically. However, high-field THz pulse generation is still demanding when compared with conventional RF generation. In this paper, we present highly efficient, single-cycle, 0.45 THz pulse generation by optical rectification of 1.03 μm pulses in cryogenically cooled lithium niobate (LN). Using a near-optimal duration of 680 fs and a pump energy of 1.2 mJ, we report conversion efficiencies above 3% [1], >10 times higher than previous report (0.24%) [2]. Cryogenic cooling of lithium niobate significantly reduces the THz absorption, which will enable the scaling of THz pulse energies to the mJ. We will also report on polarization and mode conversion using segmented THz waveplates to generate radially-polarized TEM01 modes, suitable for THz electron acceleration in dielectric waveguide.
[1] S.-W. Huang et al., Opt. Lett. 38, 796-798 (2013).
[2] J. A. Fülöp et al., Opt. Lett. 37, 557-559 (2012).

MOPSO70

Crystal Channeling Acceleration Research for High Energy Linear Collider at ASTA Facility

electron, plasma, radiation, laser

122

Y.-M. Shin
Northern Illinois University, DeKalb, Illinois, USA
K. Carlson, M.D. Church, V.D. Shiltsev, D.A. Still
Fermilab, Batavia, USA
J.C. Tobin
UMD, College Park, Maryland, USA

The density of charge carriers in solids is significantly higher than what was considered above in plasma, and correspondingly, the longitudinal fields of up to 10 TV/m are possible. It was suggested that particles are accelerated along major crystallographic directions, which provide a channeling effect in combination with low emittance determined by an Angstrom-scale aperture of the atomic “tubes.” However, the major challenge of this channeling acceleration is that ultimate acceleration gradients might require relativistic intensities at hard x-ray regime (~ 40 keV), exceeding those conceivable for x-rays as of today, though x-ray lasers can efficiently excite solid plasma and accelerate particles inside a crystal channel. However, the acceleration will take place only in a short time before full dissociation of the lattice. Carbon nanotubes have great potential with a wide range of flexibility and superior physical strength, which can be applied to channeling acceleration and possibly fast cooling. This talk will present past and current efforts on crystal acceleration research and discuss feasible experiments with the ASTA and beyond.

TUOCNO03

Progress in a Photocathode DC Gun at the Compact ERL

gun, vacuum, cathode, high-voltage

184

N. Nishimori, R. Hajima, S.M. Matsuba, R. Nagai
JAEA, Ibaraki-ken, Japan
Y. Honda, T. Miyajima, M. Yamamoto
KEK, Ibaraki, Japan
H. Iijima, M. Kuriki
HU/AdSM, Higashi-Hiroshima, Japan
M. Kuwahara
Nagoya University, Nagoya, Japan

Photocathode DC gun to produce a train of electron bunch at high-average current and small emittance is a key component of advanced accelerators for high-power beams. However, DC guns operated at a voltage above 350 kV have suffered from field emitted electrons from a support rod since the development of Lasertron in 1980's. This critical issue has been resolved by a novel configuration, segmented insulator and guard rings, adopted in a DC gun at JAEA and stable application of high voltage at 550 kV has been demonstrated. The gun has been installed at the Compact ERL at KEK and ready for the beam generation. Similar type of DC guns are under development at KEK, Cornell, JLAB and IHEP. In this talk, we present progress in photocathode DC gun for high voltage and small emittance.

Slides TUOCNO03 [4.946 MB]

TUPSO18

Optimization of Dielectric Loaded Metal Waveguides for Acceleration of Electron Bunches using Short THz Pulses

electron, space-charge, laser, emittance

250

A. Fallahi, F.X. Kaertner
CFEL, Hamburg, Germany
F.X. Kaertner, A. Sell, L.J. Wong
MIT, Cambridge, Massachusetts, USA

Funding: DARPA contract number N66001-11-1-4192 and the Center for Free-Electron Laser Science, DESY Hamburg
The last decade has witnessed extensive research efforts to reduce the size of charged particle accelerators to achieve compact devices for providing relativistic particles. To this end, various methods such as laser plasma and dielectric wakefield acceleration are investigated and their pros and cons are studied. With the advent of efficient THz generation techniques based on optical rectification, THz waveguides are also considered to be proper candidates for compact accelerators. Sofar, the proposed schemes toward high power THz generation are capable of producing short pulses, which dictates the study of particle acceleration in the pulsed regime rather than continuous-wave regime. Therefore, THz waveguides are more suitable than cavities for the considered purpose*. Consequently, various effects such as group velocity mismatch and group velocity dispersion start to influence the acceleration scenario and impose limits on the maximum energy gain from the pulse. In this contribution, we investigate electron bunch acceleration and compression in dielectrically loaded metal waveguides for the THz wavelength range and present design methodologies to optimize their performance.
* Liang Jie Wong, Arya Fallahi, and Franz X. Kärtner. "Compact electron acceleration and bunch compression in THz waveguides." Optics Express 21, no. 8 (2013): 9792-9806.

TUPSO46

Analysis and Measurement of Focusing Effects in a Traveling Wave Linear Accelerator

quadrupole, focusing, electron, simulation

329

H. Maesaka, T. Asaka, H. Ego, T. Hara, T. Inagaki, Y. Otake, T. Sakurai, H. Tanaka, K. Togawa
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

We propose a further precise model of the transverse dynamics in a traveling wave linear accelerator (TWA) and report experimental results to demonstrate the validity of the model. In SACLA, the beam orbit is calculated by using a transfer matrix based on the transverse dynamics model of each component and the matrix is utilized for orbit stabilization, beam envelop matching etc. For the TWA part, a transfer matrix including an emittance damping effect and an edge focusing effect [*] is employed. However, the beam orbit measured by rf cavity beam position monitors (RF-BPM) [**] did not agree with the calculated orbit, especially for the off-crest acceleration part. Therefore, focusing effects in a TWA structure were analyzed by using a 3-dimensional rf simulation code. The analysis indicated that the transverse dynamics model of the TWA should include an additional quadrupole edge focusing effect. The amount of the additional focusing effect of the TWA was measured in SACLA and the rf simulation result was confirmed to be consistent with the measurement. After the modification of the transverse dynamics model, the beam orbit measured by RF-BPM agrees with the calculation.
* T. Hara et al., Nucl. Instrum. Methods A 624, 65 (2010).
** H. Maesaka et al., Nucl. Instrum. Methods A 696, 66 (2012).

TUPSO59

Study of a Photocathode-based Microtron using a PIC Code

electron, microtron, laser, injection

363

S. Park
Kyungpook National University, Daegu, Republic of Korea
K.H. Jang, Y.U. Jeong, S. H. Park, N. Vinokurov
KAERI, Daejon, Republic of Korea
E.-S. Kim
KNU, Deagu, Republic of Korea
N. Vinokurov
BINP SB RAS, Novosibirsk, Russia

Korea Atomic Energy Research Institute (KAERI) has used thermionic cathode-based microtron accelerator for operating compact THz FEL due to its compact size and high energy resolution. In this thermionic cathode-based microtron, rightly phased electron bunch train are automatically accelerated during the RF macro-pulse over threshold power for their emission. But, the thermionic cathode should be replaced with a photocathode for applying the microtron to UED or THz/X-ray pump prove experiment requiring femto-second and high peak current. But, it is needed to analyze precisely the electron beam dynamics in a microtron, especially, the relation between the RF phase in a microtron cavity and Laser input time for adapting the photocathode to a microtron. Hence, we conduct computer simulation with 3D PIC-code to find those optimized conditions for operating photocathode-based microtron.