arXiv
(422.153 recursos)
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Mostrando recursos 1 - 20 de 50
1.
Symplectic Computation of Lyapunov Exponents - Habib, Salman; Ryne, Robert D.
A recently developed method for the calculation of Lyapunov exponents of
dynamical systems is described. The method is applicable whenever the
linearized dynamics is Hamiltonian. By utilizing the exponential representation
of symplectic matrices, this approach avoids the renormalization and
reorthogonalization procedures necessary in usual techniques. It is also easily
extendible to damped systems. The method is illustrated by considering two
examples of physical interest: a model system that describes the beam halo in
charged particle beams and the driven van der Pol oscillator.
2.
Order $\hbar$ Corrections to the Classical Dynamics of a Particle with
Intrinsic Spin Moving in a Constant Magnetic Field - Nash, Patrick L.
$O(\hbar)$ effects that modify the classical orbit of a charged particle are
described for the case of a classical spin-1/2 particle moving in a constant
magnetic field, using a manifestly covariant formalism reported previously. It
is found that the coupling between the momentum and spin gives rise to a shift
in the cyclotron frequency, which is explicitly calculated. In addition the
orbit is found to exhibit $O(\hbar)$ oscillations along the axis of the uniform
static magnetic field whenever the gyromagnetic ratio $g$ of the particle is
not 2. This oscillation is found to occur at a frequency $\propto$ $\frac{g}{2}
- 1$, and is an observable source of electric...
3.
Candela Photo-Injector Experimental Results - Travier, C.; Boy, L.; Cayla, J. N.; Leblond, B.; Georges, P.; Thomas, P.
The CANDELA photo-injector is a two cell S-band photo-injector. The copper
cathode is illuminated by a 500 fs Ti:sapphire laser. This paper presents
energy spectrum measurements of the dark current and intense electron emission
that occurs when the laser power density is very high.
4.
High-Brightness Photocathode Electron Sources - Travier, C.
Most present and future electron accelerators require bright sources.
Invented less than ten years ago, the photo-injector the principle of which is
briefly recalled, has already demonstrated that it can provide very bright
beams. In this paper, the most advanced photo-injector projects are reviewed,
their specific features are outlined, and their major issues are examined. The
state-of-the-art in photocathode and laser technologies is presented. Beam
dynamics issues are also considered since they are essential in the production
of bright beams. Finally, the question of the maturity of photo-injector
technology is addressed.
5.
Finding matched rms envelopes in rf linacs: A Hamiltonian approach - Ryne, Robert D.
We present a new method for obtaining matched solutions of the rms envelope
equations. In this approach, the envelope equations are first expressed in
Hamiltonian form. The Hamiltonian defines a nonlinear mapping, $\cal M$, and
for periodic transport systems the fixed points of the one-period map are the
matched envelopes. Expanding the Hamiltonian around a fiducial trajectory one
obtains a linear map, $M$, that describes trajectories (rms envelopes) near the
fiducial trajectory. Using $\cal M$ and $M$ we construct a contraction mapping
that can be used to obtain the matched envelopes. The algorithm is
quadratically convergent. Using the zero-current matched parameters as starting
values, the contraction mapping typically converges...
6.
Coupling Impedances and Heating due to Slots in the KEK B-factory - Kurennoy, Sergey S.; Chin, Yong Ho
The longitudinal and transverse coupling impedances produced by the long slots
in the Low Energy Ring of KEK B-factory are calculated. The power dissipated
inside the vacuum chamber due to the fields scattered by the slots is evaluated
using results for the real part of the coupling impedance. Estimates are made
for the power flow through the slots to the pumping chamber.
7.
A Study of Influence of Synchrotron Radiation Quantum Fluctuations on
the Synchrotron Oscillations of a Single Electron Using Undulator Radiation - Aleshaev, A. N.; Pinayev, I. V.; Popik, V. M.; Serednyakov, S. S.; Shaftan, T. V.; Sokolov, A. S.; Vinokurov, N. A.; Vorob'ev, P. V.
A single electron circulating in a storage ring is a very peculiar object.
Synchrotron radiation quantum fluctuation causes stohastic process in the
synchrotron oscillation of an electron. The radiation from a undulator permits
one to obtain discret moments of longitudional electron motion. Experiments
with a single electron on on the VEPP-3 optical klystrons are described.
8.
Muon Transverse Ionization Cooling: Stochastic Approach - Fernow, Richard C.; Gallardo, Juan C.
Transverse ionization cooling of muons is modeled as a Brownian motion of the
muon beam as it traverses a Li or Be rod. A Langevin like equation is written
for the free particle case (no external transverse magnetic field) and for the
case of a harmonically bound beam in the presence of a focusing magnetic field.
We demonstrate that the well known muon cooling equations for short-absorbers
can be extrapolated to the useful case of a long absorber rod with a focusing
magnetic field present.
9.
MONTE CARLO SIMULATIONS OF MUON PRODUCTION - Palmer, R. B.; Gallardo, J. C.; Fernow, R. C.; Torun, Y.; Neuffer, D.; Winn, D.
Muon production requirements for a muon collider are presented. Production of
muons from pion decay is studied. Lithium lenses and solenoids are considered
for focussing pions from a target, and for matching the pions into a decay
channel. Pion decay channels of alternating quadrupoles and long solenoids are
compared. Monte Carlo simulations are presented for production of $\pi
\rightarrow \mu $ by protons over a wide energy range, and criteria for
choosing the best proton energy are discussed.
10.
A General Approach for Calculating Coupling Impedances of Small
Discontinuities - Kurennoy, Sergey S.; Gluckstern, Robert L.; Stupakov, Gennady V.
A general theory of the beam interaction with small discontinuities of the
vacuum chamber is developed taking into account the reaction of radiated waves
back on the discontinuity. The reactive impedance calculated earlier is
reproduced as the first order, and the resistive one as the second order of a
perturbation theory based on this general approach. The theory also gives, in a
very natural way, the results for the trapped modes due to small
discontinuities obtained earlier by a different method.
11.
Trapped Modes in the Vacuum Chamber of an Arbitrary Cross Section - Kurennoy, Sergey S.; Stupakov, Gennady V.
It has been shown that a small discontinuity such as an enlargement or a hole
on circular waveguides can produce trapped electromagnetic modes with
frequencies slightly below the waveguide cutoff. The trapped modes due to
multiple discontinuities can lead to high narrow-band contributions to the
beam-chamber coupling impedance, especially when the wall conductivity is high
enough. To make more reliable estimates of these contributions for real
machines, an analytical theory of the trapped modes is developed in this paper
for a general case of the vacuum chamber with an arbitrary single-connected
cross section. The resonant frequencies and coupling impedances due to trapped
modes are calculated, and simple explicit expressions...
12.
Polarizabilities of an Annular Cut and Coupling Impedances of
Button-Type Beam Position Monitors - Kurennoy, Sergey S.
The longitudinal and transverse coupling impedances of a small discontinuity
on the accelerator chamber wall can be expressed in terms of the electric and
magnetic polarizabilities of the discontinuity. The polarizabilities are
geometrical factors and can be found by solving a static (electric or magnetic)
problem. However, they are known in the explicit analytical form only for a few
simple-shaped discontinuities, for example, for an elliptic hole in a thin
wall. In the present paper the polarizabilities of a ring-shaped cut in the
wall are obtained. The results are applied to calculate the coupling impedances
of button-type beam position monitors.
13.
RFQ-DRL MATCHING SOLUTIONS FOR DIFFERENT REQUIREMENTS - Raparia, D.
The Radio-Frequency Quadrupole (RFQ) has a FODO lattice and Drift-Tube-Linacs
(DTL) in general also have FODO lattices. Therefore the natural solution for
the matching between these is a FODO lattice. For matching in all three planes
one then needs sixteen degrees of freedom. However, different requirements,
depending on the applications, may change this solution. For example, in the
production environment (like medical and industrial applications), one needs
fixed current and fixed beam quality. On the other hand, in the research
environment one not only needs all degrees of freedom, but may also want to
chop of beam pulse. This paper discusses matching solutions for these different
requirements.
14.
Normal Mode Tunes for Linear Coupled Motion in Six Dimensional Phase
Space - Parzen, G.
The motion of a particle in 6-dimensional phase space in the presence of
linear coupling can be written as the sum of 3 normal modes. A cubic equation
is found for the tune of the normal modes, which allows the normal mode tunes
to be computed from the 6x6 one turn transfer matrix. This result is similar to
the quadratic equation found for the normal mode tunes for the motion of a
particle in 4-dimensional phase space. These results are useful in tracking
programs where the one turn transfer matrix can be computed by multiplying the
transfer matrices of each element of the lattice. The tunes of...
15.
Coaxial Ring Cyclotron as a Perspective Nuclear Power Engineering
Machine - Tumanyan, A. R.; Simonyan, Kh. A.; Mkrtchyan, R. L.; Amatuni, A. Ts.; Avakyan, R. O.; Khudaverdyan, A. G.
The circuit arrangement of the proposed coaxial ring cyclotron (CRC) is
described, and its main advantages, such as simple injection technique, several
injected beams summation option, high efficiency, are considered. The proposed
proton accelerator is a perspective machine for the solution of the main
problems of the present day nuclear power engineering as well as for the
next-generation nuclear power plants, representing a combination of subcritical
reactors and particle accelerators. The possibility of installation of CRCs
into ring accelerators with an average diameter from 60 to $100m$, e.g., the
Yerevan electron synchrotron, is considered.
16.
Linear Orbit Parameters for the Exact Equations of Motion - Parzen, G.
This paper defines the beta function and other linear orbit parameters using
the exact equations of motion. The orbit functions are redefined using the
exact equations. Expressions are found for the transfer matrix and the
emittances. Differential equations are found for the beta function and the eta
function. New relationships between the linear orbit parameters are found.
17.
Ultrashort Laser-pulse Diagnostics for Detection of Ordering within an
Ion beam - Calabrese, R.; Guidi, V.; Lenisa, P.; Mariotti, E.; Moi, L.; Tambini, U.
A novel diagnostic method to detect ordering within one-dimensional ion beams
in a storage ring is presented. The ions are simultaneously excited by a
ultrashort pulsed laser ($\simeq 1$ ps) at two different locations along the
beam and fluorescence is detected by a group of four photo-multipliers.
Correlation in fluorescence signals is a firm indication that the ion beam has
an ordered structure.
18.
Full Phase-Space Analysis of Particle Beam Transport in the Thermal Wave
Model - Fedele, R.; Galluccio, F.; Man'ko, V. I.; Miele, G.
Within the Thermal Wave Model framework a comparison among Wigner function,
Husimi function, and the phase-space distribution given by a particle tracking
code is made for a particle beam travelling through a linear lens with small
aberrations. The results show that the quantum-like approach seems to be very
promising.
19.
Radiation Damping and Quantum Excitation for Longitudinal Charged
Particle Dynamics in the Thermal Wave Model - Fedele, R.; Miele, G.; Palumbo, L.
On the basis of the recently proposed {\it Thermal Wave Model (TWM) for
particle beams}, we give a description of the longitudinal charge particle
dynamics in circular accelerating machines by taking into account both
radiation damping and quantum excitation (stochastic effect), in presence of a
RF potential well. The longitudinal dynamics is governed by a 1-D
Schr\"{o}dinger-like equation for a complex wave function whose squared modulus
gives the longitudinal bunch density profile. In this framework, the
appropriate {\it r.m.s. emittance} scaling law, due to the damping effect, is
naturally recovered, and the asymptotic equilibrium condition for the bunch
length, due to the competition between quantum excitation (QE) and radiation
damping...
20.
Construction of Nonlinear Symplectic Six-Dimensional Thin-Lens Maps by
Exponentiation - Heinemann, K.; Ripken, G.; Schmidt, F.
The aim of this paper is to construct six-dimensional symplectic thin-lens
transport maps for the tracking program SIXTRACK, continuing an earlier report
by using another method which consistes in applying Lie series and
exponentiation as described by W. Groebner and for canonical systems by A.J.
Dragt. We firstly use an approximate Hamiltonian obtained by a series expansion
of the square root. Furthermore, nonlinear crossing terms due to the curvature
in bending magnets are neglected. An improved Hamiltonian, excluding solenoids,
is introduced in Appendix A by using the unexpanded square root mentioned
above, but neglecting again nonlinear crossing terms...
1.
