IPAC2012 - List of Keywords (electromagnetic-fields)

Paper	Title	Other Keywords	Page
MOPPC059	Various Approaches to Electromagnetic Field Simulations for RF Cavities	simulation, cavity, impedance, HOM	268
	C. Liu, W. Ackermann, W.F.O. Müller, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by BMBF under contract 05H09RD5. The Superconducting Proton Linac (SPL) cavity is mainly designed and conducted by CERN. It is a part of the planned injector upgrade of the Large Hadron Collider (LHC). The SPL cavity is used to accelerate the ion beam from 160 MeV to 5GeV and served as a driver for neutrino facilities and radioactive beam facilities. In the Superconducting Proton Linac (SPL) cavity, it is very important to calculate the eigenmodes precisely, because many higher-order modes (HOMs) can lead to particle beam instabilities. We used and compared three different ways to calculate the eigenmodes in the SPL cavity: field simulation with hexahedron mesh in frequency domain, field simulation with hexahedron mesh in time domain, and field simulation with tetrahedral mesh and higher order curvilinear elements. In this paper the principles of the three numerical methods will be introduced and compared. Finally the calculated results will be presented.

MOPPC069	Quantitative Simulation of NIRS-930 Cyclotron	cyclotron, acceleration, extraction, simulation	292
	V.L. Smirnov, S.B. Vorozhtsov JINR/DLNP, Dubna, Moscow region, Russia A. Goto, S. Hojo, T. Honma, K. Katagiri NIRS, Chiba-shi, Japan
	The results of the computer modelling of the structural elements of the NIRS-930 cyclotron operational at the National Institute of Radiological Sciences (Chiba, Japan) are presented. The integrated approach to modelling of the cyclotron, including calculation of electromagnetic fields of the structural elements and beam dynamics simulations is described. A computer model of the cyclotron was constructed. Electric and magnetic field distributions and mechanical structures were converted to the beam dynamics code for simulations, in which particle losses on the surfaces of the system elements were estimated. The existing data on the axial injection, magnetic, acceleration and extraction systems of the cyclotron and beam parameter measurements are used for calibration of the simulations. New acceleration regimes could be formulated with the help of the constructed computer model of the machine.

MOPPR006	Surface Waves for Testing of Beam Instrumentation	instrumentation, impedance, resonance, induction	780
	F. Stulle, J.F. Bergoz BERGOZ Instrumentation, Saint Genis Pouilly, France
	The fundamental TM wave can be guided as a surface wave along a single dielectric coated wire. Such a setup is known as a Goubau line. Close to the wire the TM wave resembles closely the radial electric and azimuthal magnetic fields of a charged particle beam moving in an accelerator. Hence, it can be used to test beam instrumentation in the workshop. We introduce the principle, discuss benefits, and compare measurements of a beam instrumentation device performed with a Goubau line to measurements performed with a standard bench testing setup.

TUPPR067	Electromagnetic Field of Charged Particle Bunch Moving in Wire Metamaterial	radiation	1975
	V.V. Vorobev, A.V. Tyukhtin Saint-Petersburg State University, Saint-Petersburg, Russia
	Funding: Saint Petersburg State University We consider the field of bunch flying through a "wire metamaterial". Analytical and computational investigations are carried out. In the case of motion perpendicularly to the wires it is shown that the radiation concentrates in a small vicinity of the determined lines behind the bunch and the Pointing vector is directed along the wires. This phenomenon can be useful for charged bunch examination. Some calculations show that the measurements of electrical field intensity and energy flow density allow determining the length of the bunch and its velocity. The case of bunch moving along the wires is also examined. It is shown that the radiation can be generated only for the wires possessing non-conducting coating. The radiation is directed at a sharp angle to the wires.

WEPPC056	Pressure Sensitivity Characterization of Superconducting Spoke Cavities	cavity, simulation, linac, resonance	2339
	D. Passarelli, M.H. Awida, I.V. Gonin, L. Ristori, V.P. Yakovlev Fermilab, Batavia, USA
	The following proposal illustrates a method to characterize the pressure sensitivity behavior of superconducting spoke cavities. This methodology relies on evaluating the variation of resonant frequency of a cavity by observing only the displacements at designed regions of the cavity. The proposed method permits a reduced computational burden and a systematic approach to achieve a minimum value of pressure sensitivity in a complex system of dressed cavity. This method has been used to characterize the superconducting spoke cavities typs⁻¹ (SSR1), under development for Project X, and to design the helium containment vessel in such way to reduce the pressure sensitivity value to zero.

WEPPP024	Cherenkov Radiation from a Small Bunch Moving in a Cold Magnetized Plasma	plasma, radiation, wakefield, acceleration	2775
	S.N. Galyamin, D.Y. Kapshtan, A.V. Tyukhtin Saint-Petersburg State University, Saint-Petersburg, Russia
	Funding: Saint Petersburg State University. Investigation of the bunch radiation in plasma is important for the plasma wakefield acceleration (PWFA) technique and other applications in accelerator physics. We study the electromagnetic field of small relativistic bunch moving in a magnetized cold plasma along the magnetic field. The energy loss of the bunch was investigated earlier, however the structure of electromagnetic field was not analyzed. We perform analytical and numerical investigation of total field. Different equivalent representations for the field components are obtained. One of them allows separating quasistatic field and radiation one. Method of computation is developed as well. Some interesting physical effects are described. One of them is strong increase of some components of radiation field near the charge motion line (in the case of point charge). The case of a charged disc is considered as well. Prospects of use of obtained results for PWFA are discussed.

WEPPR025	Effective Emittance Growth in Beam with Gaussian Density Profile	emittance, plasma	2988
	H.Y. Barminova ITEP, Moscow, Russia
	In a continuous beam with nonuniform charge density profile transverse oscillations are nonlinear resulting in effective emittance growth. It is of great practical interest to find this growth scaling law in the case of beam with Gaussian density distribution. To study the effect for a sheet beam with parabolic density profile, a fully kinetic and self-consistent model was built. The model allows one to obtain equations for envelope radius and rms emittance in a self-consistent manner, as the KV-model does it. The only model requirement is a special type of distribution function depending on the integral of nonlinear motion equations that automatically satisfies the Vlasov equation. The envelope equation is proved to be an ODE of 4th order. It was solved by the Runge-Kutta method. The beam parameter range was found where rms emittance growth is absent. The stationary equilibrium solution was found, too. The stability of solutions near equilibrium one was studied. An analysis of results shows that when there is no energy dissipation in the channel, rms emittance rises due to phase mixing between envelope oscillations and density distribution shape oscillations.

THPPC017	Study of Physical Processes of Acceleration of Electron Bunches with Extremal Density by Means of Stored Energy in Disk Loaded Waveguide Sections	electron, linac, acceleration, radiation	3314
	S. Proskin, A. Kulago MEPhI, Moscow, Russia
	This presentation should consider a new theoretical method of SHF power increasing in DWLG sections. Within the presentation physical processes of the acceleration of extremely charge densities in the sections of a DWLG by the stored energy are described. As a result optimum travelling wave DWLG is taken and a simulation of acceleration processes of 20 ns electron beams is conducted.

Paper

Title

Other Keywords

Page

MOPPC059

Various Approaches to Electromagnetic Field Simulations for RF Cavities

simulation, cavity, impedance, HOM

268

C. Liu, W. Ackermann, W.F.O. Müller, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: Work supported by BMBF under contract 05H09RD5.
The Superconducting Proton Linac (SPL) cavity is mainly designed and conducted by CERN. It is a part of the planned injector upgrade of the Large Hadron Collider (LHC). The SPL cavity is used to accelerate the ion beam from 160 MeV to 5GeV and served as a driver for neutrino facilities and radioactive beam facilities. In the Superconducting Proton Linac (SPL) cavity, it is very important to calculate the eigenmodes precisely, because many higher-order modes (HOMs) can lead to particle beam instabilities. We used and compared three different ways to calculate the eigenmodes in the SPL cavity: field simulation with hexahedron mesh in frequency domain, field simulation with hexahedron mesh in time domain, and field simulation with tetrahedral mesh and higher order curvilinear elements. In this paper the principles of the three numerical methods will be introduced and compared. Finally the calculated results will be presented.

MOPPC069

Quantitative Simulation of NIRS-930 Cyclotron

cyclotron, acceleration, extraction, simulation

292

V.L. Smirnov, S.B. Vorozhtsov
JINR/DLNP, Dubna, Moscow region, Russia
A. Goto, S. Hojo, T. Honma, K. Katagiri
NIRS, Chiba-shi, Japan

The results of the computer modelling of the structural elements of the NIRS-930 cyclotron operational at the National Institute of Radiological Sciences (Chiba, Japan) are presented. The integrated approach to modelling of the cyclotron, including calculation of electromagnetic fields of the structural elements and beam dynamics simulations is described. A computer model of the cyclotron was constructed. Electric and magnetic field distributions and mechanical structures were converted to the beam dynamics code for simulations, in which particle losses on the surfaces of the system elements were estimated. The existing data on the axial injection, magnetic, acceleration and extraction systems of the cyclotron and beam parameter measurements are used for calibration of the simulations. New acceleration regimes could be formulated with the help of the constructed computer model of the machine.

MOPPR006

Surface Waves for Testing of Beam Instrumentation

instrumentation, impedance, resonance, induction

780

F. Stulle, J.F. Bergoz
BERGOZ Instrumentation, Saint Genis Pouilly, France

The fundamental TM wave can be guided as a surface wave along a single dielectric coated wire. Such a setup is known as a Goubau line. Close to the wire the TM wave resembles closely the radial electric and azimuthal magnetic fields of a charged particle beam moving in an accelerator. Hence, it can be used to test beam instrumentation in the workshop. We introduce the principle, discuss benefits, and compare measurements of a beam instrumentation device performed with a Goubau line to measurements performed with a standard bench testing setup.

TUPPR067

Electromagnetic Field of Charged Particle Bunch Moving in Wire Metamaterial

radiation

1975

V.V. Vorobev, A.V. Tyukhtin
Saint-Petersburg State University, Saint-Petersburg, Russia

Funding: Saint Petersburg State University
We consider the field of bunch flying through a "wire metamaterial". Analytical and computational investigations are carried out. In the case of motion perpendicularly to the wires it is shown that the radiation concentrates in a small vicinity of the determined lines behind the bunch and the Pointing vector is directed along the wires. This phenomenon can be useful for charged bunch examination. Some calculations show that the measurements of electrical field intensity and energy flow density allow determining the length of the bunch and its velocity. The case of bunch moving along the wires is also examined. It is shown that the radiation can be generated only for the wires possessing non-conducting coating. The radiation is directed at a sharp angle to the wires.

WEPPC056

Pressure Sensitivity Characterization of Superconducting Spoke Cavities

cavity, simulation, linac, resonance

2339

D. Passarelli, M.H. Awida, I.V. Gonin, L. Ristori, V.P. Yakovlev
Fermilab, Batavia, USA

The following proposal illustrates a method to characterize the pressure sensitivity behavior of superconducting spoke cavities. This methodology relies on evaluating the variation of resonant frequency of a cavity by observing only the displacements at designed regions of the cavity. The proposed method permits a reduced computational burden and a systematic approach to achieve a minimum value of pressure sensitivity in a complex system of dressed cavity. This method has been used to characterize the superconducting spoke cavities typs⁻¹ (SSR1), under development for Project X, and to design the helium containment vessel in such way to reduce the pressure sensitivity value to zero.

WEPPP024

Cherenkov Radiation from a Small Bunch Moving in a Cold Magnetized Plasma

plasma, radiation, wakefield, acceleration

2775

S.N. Galyamin, D.Y. Kapshtan, A.V. Tyukhtin
Saint-Petersburg State University, Saint-Petersburg, Russia

Funding: Saint Petersburg State University.
Investigation of the bunch radiation in plasma is important for the plasma wakefield acceleration (PWFA) technique and other applications in accelerator physics. We study the electromagnetic field of small relativistic bunch moving in a magnetized cold plasma along the magnetic field. The energy loss of the bunch was investigated earlier, however the structure of electromagnetic field was not analyzed. We perform analytical and numerical investigation of total field. Different equivalent representations for the field components are obtained. One of them allows separating quasistatic field and radiation one. Method of computation is developed as well. Some interesting physical effects are described. One of them is strong increase of some components of radiation field near the charge motion line (in the case of point charge). The case of a charged disc is considered as well. Prospects of use of obtained results for PWFA are discussed.

WEPPR025

Effective Emittance Growth in Beam with Gaussian Density Profile

emittance, plasma

2988

H.Y. Barminova
ITEP, Moscow, Russia

In a continuous beam with nonuniform charge density profile transverse oscillations are nonlinear resulting in effective emittance growth. It is of great practical interest to find this growth scaling law in the case of beam with Gaussian density distribution. To study the effect for a sheet beam with parabolic density profile, a fully kinetic and self-consistent model was built. The model allows one to obtain equations for envelope radius and rms emittance in a self-consistent manner, as the KV-model does it. The only model requirement is a special type of distribution function depending on the integral of nonlinear motion equations that automatically satisfies the Vlasov equation. The envelope equation is proved to be an ODE of 4th order. It was solved by the Runge-Kutta method. The beam parameter range was found where rms emittance growth is absent. The stationary equilibrium solution was found, too. The stability of solutions near equilibrium one was studied. An analysis of results shows that when there is no energy dissipation in the channel, rms emittance rises due to phase mixing between envelope oscillations and density distribution shape oscillations.

THPPC017

Study of Physical Processes of Acceleration of Electron Bunches with Extremal Density by Means of Stored Energy in Disk Loaded Waveguide Sections

electron, linac, acceleration, radiation

3314

S. Proskin, A. Kulago
MEPhI, Moscow, Russia

This presentation should consider a new theoretical method of SHF power increasing in DWLG sections. Within the presentation physical processes of the acceleration of extremely charge densities in the sections of a DWLG by the stored energy are described. As a result optimum travelling wave DWLG is taken and a simulation of acceleration processes of 20 ns electron beams is conducted.