چكيده به لاتين
Iranian Light Source Facility (ILSF) is a fourth-generation light source under design and construction in Qazvin city. The circumference of the ILSF storage ring is 528 m and its horizontal emittance is 270 pm-rad which will be enable to produce photons with the brilliance of 1×10^21 [((photons/s)/〖mm〗^2 )/〖mrad〗^2 /0.1BW%] for the wide range of the researchers and scientists.
In this thesis, the optics design and performance of the ILSF storage ring has been investigated in the presence of various types of errors and disruptions. In order to achieve a very small horizontal emittance, the optics of storage ring is based on multi-bend achromat lattice. By choosing such a lattice, the ILSF storage ring will consists of 20 super-periods. Of this number of straight sections, 17 straights will be allocated for installation of insertion devices. In addition, the radio frequency cavities will be installed in the 2 straight sections. The injection equipment will be installed in another straight section.
To further reduce the emittance, the dipole magnets have simultaneously the dipole and quadrupole magnetic field component. Since the emittance of the lattice is determined mainly by the emittance of unit cell, the gradient of the dipole and quadrupole magnets was determined according to the optimization process to reach the lowest possible emittance.
In the design of new generation storage rings, the use of strong quadrupole magnets is inevitably needed to achieve very small emittance. In order to correct the chromatic aberration caused by quadrupoles, as well as avoiding head-tail instability, it is necessary to use strong sextupole magnets. Sextupole magnets, due to the presence of non-linear fields in certain amplitudes, cause chaotic electron motion and unstable beam. One of the main challenges in the design of the new generation storage rings is chaotic motion of the electrons in smaller amplitudes due to the strong field of sextupole magnets. In this thesis, in order to solve this challenge, by calculating the Hamiltonian of electrons motion inside storage ring and solving it using perturbation method, an optimal distribution for the strength and location of the sextupole magnets is obtained such that the electron motion to be regular at least in the range of electrons injected amplitude into the ring. To do this, particle tracking and electron motion frequency mapping analysis were used.
Due to the limited tolerances in the construction and alignment of different magnets and girders within the storage ring and the presence of insertion devices with essential nonlinear fields, in the real machine, various disturbances will affect the rotating beam within the storage ring. Employing the SVD algorithm, the distortion of the electron paths generated by the dipolar field due to alignment errors and field error is corrected and reduced to the acceptable values. Since the alignment and field errors affect the electrons closed orbit and produce coupling in transverce plan, it will have significant effect on the nonlinear beam dynamics. The direct computation of the dynamic aperture and frequency map analysis are used to identify the excited resonances and their effect on the lattice dynamic aperture.
Due to the very small emittance of ILSF storage ring and, therefore, the small horizontal dispersion function, the lattice has small momentum compaction factor. Because of this, the length of the electron bunches is short and, as a result, the interaction of the electron with the electron and the electron with the environment (vacuum chamber) are strong. In other words, the collective effects, is much stronger than that of the other storage rings. Two scattering phenomena so-called Touscheck and intra-beam scattering are two type of electron-electron scattering that have a detrimental effect on the lifetime and emittance of the electrons inside the storage ring. Six-dimensional particle tracking is used to study and calculate their effects on the storage ring parameters. To investigate the performance of the designed lattice, a series of instabilities that are caused by the interaction of the electron with the environment were studied. Coherent synchrotron radiation and transverse mode coupling instability are investigated analytically, and the instabilities threshold are obtained for each of them.
Beam injection into storage ring has been investigated by using two methods. As a first method, I have studied the beam injection using four dipolar kickers. It is common method for injecting beam into storage ring. In the second method, the beam injecting using nonlinear multipole kicker has been investigated. By studying the beam dynamics of the injection process, the required field tolerance, pulse shaping (power supply accuracy), septum performance, time jitter, and energy mismatch of the injected beam are obtained.
