Astigmatism correction with an adaptive quadrupole and an expander lens for electron accelerators

Date

2019-12-01

Author

Durna, Emre
Sanal, Mustafa Golchan
Yayla, Mahmut Sinan

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

72
views

0
downloads

Astigmatism is a type of aberration in beam optics which causes asymmetry in transverse coordinates. This asymmetric beam often shows an elliptical profile instead of circular, which may cause differences between the major and minor ellipse axes diameters and ellipse azimuth angle. In this research work, a novel astigmatism correction system is proposed for electron accelerators with a minimum number of electromagnetic lenses. An adaptive quadrupole lens is designed by coaxially locating two quadrupoles 45 degrees apart from each other. The focusing and defocusing axes and the azimuth angle of the resultant adaptive quadrupole are determined adaptively by the vector sum of created magnetic fields of two coaxially located quadrupoles. The adaptive quadrupole lens is placed on the common focal point of two solenoids as part of an expander lens. In this way, the focal points of the major and minor axes of an elliptical beam are slightly changed from the common focal point of the expander. This act helps to increase the minor axis diameter of the electron beam while decreasing the major one, resulting in a circular profile. Both a 2D beam trajectory model in MATLAB and a 3D Particle Accelerator simulation with Computer Simulation Technology (CST) tool show that the proposed method successfully corrects the astigmatism having any elliptical parameters for a sample electron beam.

URI

https://hdl.handle.net/11511/92273

Journal

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS

DOI

https://doi.org/10.1016/j.nimb.2019.09.011

Collections

Department of Physics, Article

Suggestions

OpenMETU
Core

DIRECTIONAL DEPENDENCE OF EXTRAORDINARY INFRARED OSCILLATOR PARAMETERS OF TLGAS2-TYPE LAYER CRYSTALS Hasanlı, Nızamı; TAGIROV, VI (Elsevier BV, 1983-01-01) The directional dispersion of IR-active modes of TlGaS2, TlGaSe2 and TlInS2 layersingle crystals has been investigated, depending on the angle between the phonon wave vector q and the optical c-axis. Owing to the possibility of preparation crystals with various orientations of reflecting surfaces with respect to the optical c-axis, it was of interest to check the applicability of the generalized Born and Huang theory of long-wave optical vibrations in uniaxial crystals to TlGaS2-type layer crystals.
Asymmetric transmission of linearly polarized electromagnetic waves using chiral metamaterials with constant chirality over a certain frequency band Akgöl, Oğuzhan; Dinçer, Furkan; Karaaslan, Muharrem; Ünal, Emin; Sabah, Cumali (World Scientific Pub Co Pte Lt, 2014-12-30) In this study, a dynamic chiral metamaterial (MTM) structure leading to an asymmetric electromagnetic (EM) wave transmission for linear polarization is presented. The structure is composed of square-shaped resonator with gaps on both sides of a dielectric substrate with a certain degree of rotation. The dynamic structure is adjustable via various parameters to fit any desired frequency ranges. Theoretical and experimental analysis of the proposed structure are conducted and given in detail. The suggested mo...
Optical nonlinearity versus mechanical anharmonicity contrast in dynamic mode apertureless scanning near-field optical microscopy Bek, Alpan; Kern, K (2005-10-01) We show that the contrast mechanism in dynamic mode apertureless scanning near-field optical microscopy is in general a combination of both spatially nonlinear optical interaction and temporally anharmonic mechanical cantilever motion. Mechanical factors are found experimentally to easily overshadow the optical signal, leading to artifacts not yet well documented in the literature. Our algebraic analysis provides a systematic framework to identify and control the relative influence of the competing contrast...
Excitonic effects on the nonlinear optical properties of small quantum dots KARABULUT, İBRAHİM; Safak, H.; Tomak, Mehmet (IOP Publishing, 2008-08-07) The excitonic effects on the nonlinear optical properties of small quantum dots with a semiparabolic confining potential are studied under the density matrix formalism. First, within the framework of the strong confinement approximation, we present the excitonic states and then calculate the excitonic effects on the nonlinear optical properties, such as second harmonic generation, third harmonic generation, nonlinear absorption coefficient and refractive index changes. We find the explicit analytical expres...
Real-time scanning hall probe microscopy Oral, Ahmet; HENİNİ, M (1996-08-26) We describe a low-noise scanning Hall probe microscope having unprecedented magnetic field sensitivity (similar to 2.9x10(-8) T/root Hz at 77 K), high spatial resolution, (similar to 0.85 mu m),nd operating in real-time (similar to 1 frame/s) for studying flux profiles at surfaces. A submicron Hall probe manufactured in a GaAs/A1GaAs two-dimensional electron gas (2DEG) is scanned over the sample to measure the surface magnetic fields using conventional scanning tunneling microscopy positioning techniques. F...

Citation Formats

E. Durna, M. G. Sanal, and M. S. Yayla, “Astigmatism correction with an adaptive quadrupole and an expander lens for electron accelerators,” NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, vol. 461, pp. 25–29, 2019, Accessed: 00, 2021. [Online]. Available: https://hdl.handle.net/11511/92273.