TY - CONF
AU - Niedermayer, U.
AU - Adelmann, A.
AU - Aßmann, R.W.
AU - Bettoni, S.
AU - Black, D.S.
AU - Boine-Frankenheim, O.
AU - Broaddus, P. N.
AU - Byer, R.L.
AU - Calvi, M.
AU - Cankaya, H.
AU - Ceballos, A.C.
AU - Cesar, D.B.
AU - Cowan, B.M.
AU - Dehler, M.M.
AU - Deng, H.
AU - Dorda, U.
AU - Egenolf, T.
AU - England, R.J.
AU - Fakhari, M.
AU - Fallahi, A.
AU - Fan, S.
AU - Ferrari, E.
AU - Feurer, T.
AU - Frei, F.
AU - Harris, J.S.
AU - Hartl, I.
AU - Hauenstein, D.
AU - Hermann, B.
AU - Hiller, N.
AU - Hirano, T.
AU - Hommelhoff, P.
AU - Huang, Y.-C.
AU - Huang, Z.
AU - Hughes, T.W.
AU - Illmer, J.
AU - Ischebeck, R.
AU - Jiang, Y.
AU - Kuropka, W.
AU - Kärtner, F.X.
AU - Langenstein, T.
AU - Lee, Y.J.
AU - Leedle, K.J.
AU - Lemery, F.
AU - Li, A.
AU - Lombosi, C.
AU - Marchetti, B.
AU - Mayet, F.
AU - Miao, Y.
AU - Mittelbach, A.K.
AU - Musumeci, P.
AU - Naranjo, B.
AU - Pigott, A.
AU - Prat, E.
AU - Qi, M.
AU - Reiche, S.
AU - Rivkin, L.
AU - Rosenzweig, J.B.
AU - Sapra, N.
AU - Schönenberger, N.
AU - Shen, X.
AU - Shiloh, R.
AU - Simakov, E.I.
AU - Skär, E.
AU - Solgaard, O.
AU - Su, L.
AU - Tafel, A.D.
AU - Tan, S.
AU - Vuckovic, J.
AU - Xuan, H.
AU - Yang, K.
AU - Yousefi, P.
AU - Zhao, Z.
AU - Zhu, J.
ED - Schaa, Volker RW
ED - Makino, Kyoko
ED - Snopok, Pavel
ED - Berz, Martin
TI - Challenges in Simulating Beam Dynamics of Dielectric Laser Acceleration
J2 - Proc. of ICAP2018, Key West, FL, USA, 20-24 October 2018
CY - Key West, FL, USA
T2 - International Computational Accelerator Physics Conference
T3 - 13
LA - english
AB - Dielectric Laser Acceleration (DLA) achieves the high- est gradients among structure-based electron accelerators. The use of dielectrics increases the breakdown field limit, and thus the achievable gradient, by a factor of at least 10 in comparison to metals. Experimental demonstrations of DLA in 2013 led to the Accelerator on a Chip International Program (ACHIP), funded by the Gordon and Betty Moore Foundation. In ACHIP, our main goal is to build an acceler- ator on a silicon chip, which can accelerate electrons from below 100keV to above 1MeV with a gradient of at least 100MeV/m. For stable acceleration on the chip, magnet- only focusing techniques are insufficient to compensate the strong acceleration defocusing. Thus spatial harmonic and Alternating Phase Focusing (APF) laser-based focusing tech- niques have been developed. We have also developed the simplified symplectic tracking code DLAtrack6D, which makes use of the periodicity and applies only one kick per DLA cell, which is calculated by the Fourier coefficient of the synchronous spatial harmonic. Due to coupling, the Fourier coefficients of neighboring cells are not entirely independent and a field flatness optimization (similarly as in multi-cell cavities) needs to be performed. The simu- lation of the entire accelerator on a chip by a Particle In Cell (PIC) code is possible, but impractical for optimization purposes. Finally, we have also outlined the treatment of wake field effects in attosecond bunches in the grating within DLAtrack6D, where the wake function is computed by an external solver.
PB - JACoW Publishing
CP - Geneva, Switzerland
SP - 120
EP - 126
KW - laser
KW - electron
KW - focusing
KW - experiment
KW - acceleration
DA - 2019/01
PY - 2019
SN - 978-3-95450-200-4
DO - DOI: 10.18429/JACoW-ICAP2018-MOPLG01
UR - http://jacow.org/icap2018/papers/moplg01.pdf
ER -
TY - CONF
AU - Heinemann, K.A.
AU - Appelö, D.
AU - Barber, D.P.
AU - Beznosov, O.
AU - Ellison, J.A.
ED - Schaa, Volker RW
ED - Makino, Kyoko
ED - Snopok, Pavel
ED - Berz, Martin
TI - Spin Dynamics in Modern Electron Storage Rings: Computational and Theoretical Aspects
J2 - Proc. of ICAP2018, Key West, FL, USA, 20-24 October 2018
CY - Key West, FL, USA
T2 - International Computational Accelerator Physics Conference
T3 - 13
LA - english
AB - In this talk we present some numerical and analytical results from our work on the spin polarization in high energy electron storage rings. Our work is based on the initial value problem of what we call the full Bloch equations (FBEs). The solution of the FBEs is the polarization density which is proportional to the spin angular momentum density per particle in phase space and which determines the polarization vector of the bunch. The FBEs take into account spin diffusion effects and spin-flip effects due to synchrotron radiation including the Sokolov-Ternov effect and its Baier-Katkov generalization. The FBEs were introduced by Derbenev and Kondratenko in 1975 as a generalization of the Baier-Katkov-Strakhovenko equations from a single orbit to the whole phase space. The FBEs are a system of three uncoupled Fokker-Planck equations plus two coupling terms, i.e., the T-BMT term and the Baier-Katkov term. Neglecting the spin flip terms in the FBEs one gets what we call the reduced Bloch equations (RBEs). The RBEs are sufficient for computing the depolarization time. The conventional approach of estimating and optimizing the polarization is not based on the FBEs but on the so-called Derbenev-Kondratenko formulas. However, we believe that the FBEs offer a more complete starting point for very high energy rings like the FCC-ee and CEPC. The issues for very high energy are: (i) Can one get polarization, (ii) are the Derbenev-Kondratenko formulas satisfactory at very high energy? If not, what are the theoretical limits of the polarization? Item (ii) will be addressed both numerically and analytically. Our numerical approach has three parts. Firstly we approximate the FBEs analytically using the method of averaging, resulting in FBEs which allow us to use large time steps (without the averaging the time dependent coefficients of the FBEs would necessitate small time steps). The minimum length of the time interval of interest is of the order of the orbital damping time. Seco
PB - JACoW Publishing
CP - Geneva, Switzerland
SP - 127
EP - 133
KW - polarization
KW - storage-ring
KW - electron
KW - radiation
KW - synchrotron
DA - 2019/01
PY - 2019
SN - 978-3-95450-200-4
DO - DOI: 10.18429/JACoW-ICAP2018-MOPLG03
UR - http://jacow.org/icap2018/papers/moplg03.pdf
ER -
TY - CONF
AU - Beznosov, O.
AU - Appelö, D.
AU - Barber, D.P.
AU - Ellison, J.A.
AU - Heinemann, K.A.
ED - Schaa, Volker RW
ED - Makino, Kyoko
ED - Snopok, Pavel
ED - Berz, Martin
TI - Spin Dynamics in Modern Electron Storage Rings: Computational Aspects
J2 - Proc. of ICAP2018, Key West, FL, USA, 20-24 October 2018
CY - Key West, FL, USA
T2 - International Computational Accelerator Physics Conference
T3 - 13
LA - english
AB - In this talk we present some numerical results from our work on the spin polarization in high energy electron storage rings. The motivation of our work is to understand spin polarization in very high energy rings like the proposed Future Circular Collider* (FCC-ee) and Circular Electron Positron Collider** (CEPC). This talk is a supplement to K. Heinemann’s talk and gives further numerical details and results. As discussed in Heinemann’s talk our work is based on the initial value problem of the full Bloch equations*** (FBEs) which in turn determines the polarization vector of the bunch. The FBEs take into account spin diffusion effects and spin-flip effects due to synchrotron radiation. The FBEs are a system of three uncoupled Fokker-Planck equations plus coupling terms. Neglecting the spin flip terms in the FBEs one gets the reduced Bloch equations (RBEs) which poses the main computational challenge. Our numerical approach has three parts. Firstly we approximate the FBEs analytically using the method of averaging, resulting in FBEs which allow us to use large time steps (without the averaging the time dependent coefficients of the FBEs would necessitate small time steps). The minimum length of the time interval of interest is of the order of the orbital damping time. Secondly we discretize the averaged FBEs in the phase space variables by applying the pseudospectral method, resulting in a system of linear first-order ODEs in time. The phase space variables come in d pairs of polar coordinates where d = 1, 2, 3 is the number of degrees of freedom allowing for a d-dimensional Fourier expansion. The pseudospectral method is applied by using a Chebychev grid for each radial variable and a uniform Fourier grid for each angle variable. Thirdly we discretize the ODE system by a time stepping scheme. The presence of parabolic terms in the FBEs necessitates implicit time stepping and thus solutions of linear systems of equations. Dealing with 2d + 1 independent variables p
PB - JACoW Publishing
CP - Geneva, Switzerland
SP - 146
EP - 150
KW - polarization
KW - electron
KW - storage-ring
KW - radiation
KW - coupling
DA - 2019/01
PY - 2019
SN - 978-3-95450-200-4
DO - DOI: 10.18429/JACoW-ICAP2018-MOPAF04
UR - http://jacow.org/icap2018/papers/mopaf04.pdf
ER -
TY - CONF
AU - Krasilnikov, M.
AU - Boonpornprasert, P.
AU - Nuhn, H.-D.
AU - Schneidmiller, E.
AU - Stephan, F.
AU - Yurkov, M.V.
ED - Schaa, Volker RW
ED - Makino, Kyoko
ED - Snopok, Pavel
ED - Berz, Martin
TI - Start-to-End Simulations of THz SASE FEL Proof-of-Principle Experiment at PITZ
J2 - Proc. of ICAP2018, Key West, FL, USA, 20-24 October 2018
CY - Key West, FL, USA
T2 - International Computational Accelerator Physics Conference
T3 - 13
LA - english
AB - The Photo Injector Test facility at DESY in Zeuthen (PITZ) develops high brightness electron sources for modern linac-based Free Electron Lasers (FELs). The PITZ accelerator has been proposed as a prototype for a tunable, high power THz source for pump and probe experiments at the European XFEL. A Self-Amplified Spontaneous Emission (SASE) FEL is considered to generate the THz pulses. High radiation power can be achieved by utilizing high charge (4 nC) shaped electron bunches from the PITZ photo injector. THz pulse energy of up to several mJ is expected from preliminary simulations for 100 um radiation wavelength. For the proof-of-principle experiments a re-usage of LCLS-I undulators at the end of the PITZ beamline is under studies. One of the challenges for this setup is transport and matching of the space charge dominated electron beam through the narrow vacuum chamber. Start-to-end simulations for the entire experimental setup - from the photocathode to the SASE THz generation in the undulator section - have been performed by combination of several codes: ASTRA, SC and GENESIS-1.3. The space charge effect and its impact onto the output THz radiation have been studied. The results of these simulations will be presented and discussed.
PB - JACoW Publishing
CP - Geneva, Switzerland
SP - 246
EP - 252
KW - undulator
KW - electron
KW - simulation
KW - FEL
KW - emittance
DA - 2019/01
PY - 2019
SN - 978-3-95450-200-4
DO - DOI: 10.18429/JACoW-ICAP2018-TUPAF23
UR - http://jacow.org/icap2018/papers/tupaf23.pdf
ER -