Integral Nested Sliding Mode Control for Antilock Brake System

An integral nested Sliding Mode (SM) Control is proposed for an Antilock Brake System (ABS) control problem by employing integral SM and nested SM concepts. This controller has robustness against matched and unmatched perturbations, and the capability to reduce the sliding functions gains. Application to an ABS is presented as a simulationConsejo Nacional de Ciencia y TecnologíaLomonosov Moscow State UniversityUniversidad Autónoma Metropolitana-AzcapotzalcoUniversidad de Guadalajar

Advanced Simulations of Optical Transition and Diraction Radiation

Charged particle beam diagnostics is a key task in modern and future accelerator installations. The diagnostic tools are practically the “eyes” of the operators. The precision and resolution of the diagnostic equipment are crucial to define the performance of the accelerator. Transition and diffraction radiation (TR and DR) are widely used for electron beam parameter monitoring. However, the precision and resolution of those devices are determined by how well the production, transport and detection of these radiation types are understood. This paper reports on simulations of TR and DR spatial-spectral characteristics using the physical optics propagation (POP) mode of the Zemax advanced optics simulation software. A good consistency with theory is demonstrated. Also, realistic optical system alignment issues are discussed

Improvement of Beam Imaging Systems through Optics Propagation Simulations

Optical Transition Radiation (OTR) is emitted when a charged particle crosses the interface between two media with different dielectric properties. It has become a wide-spread method for beam profile measurements. However, there are no tools to simulate the propagation of the OTR electric field through an optical system. Simulations using ZEMAX have been performed in order to quantify optical errors, such as aberrations, diffraction, depth of field and misalignment. This paper focuses on simulations of vertically polarized OTR photons with the aim of understanding what limits the resolution of realistic beam imaging systems

Comparison of Optical Transition Radiation Simulations and Theory

The majority of optical diagnostics currently used will not stand up to the requirements of the next generation of particle accelerators. Current methodologies need innovation to be able to reach the sub-micrometre resolution and sensitivity that will be required. One technique that has the potential to meet these requirements is optical transition radiation (OTR) imaging. A new algorithm is proposed which incorporates OTR theory, optical effects and beam distribution. This algorithm takes an existing method used for beam imaging and pushes the limits resolution beyond that normally attainable. In doing so, it can provide a reliable and economical diagnostic for future accelerators. A discussion on further applications of the algorithm is also presented

Diffraction Radiation for Non-Invasive, High-Resolution Beam Size Measurements in Future Linear Colliders

Next generation linear colliders such as the Compact Linear Collider (CLIC) or the International Linear Collider (ILC) will accelerate particle beams with extremely small emittance. The high current and small size of the beam (micron-scale) due to such small emittance require non-invasive, high-resolution techniques for beam diagnostics. Diffraction Radiation (DR), a polarization radiation that appears when a charged particle moves in the vicinity of a medium, is an ideal candidate being non-invasive and allowing beams as small as a few tens of microns to be measured. Since DR is sensitive to beam parameters other than the transverse profile (e.g. its divergence and position), preparatory simulations have been performed with realistic beam parameters. A new dedicated instrument was installed in the KEK-ATF2 beam line in February 2016. At present DR is observed in the visible wavelength range, with an upgrade to the ultraviolet (200nm) planned for spring 2017 to optimize sensitivity to smaller beam sizes. Presented here are the latest results of these DR beam size measurements and simulations

Optical Effects in High Resolution and High Dynamic Range Beam Imaging Systems

Optical systems are used to transfer light in beam diagnostics for a variety of imaging applications. The effect of the point spread function (PSF) of these optical systems on the resulting measurements is often approximated or misunderstood. It is imperative that the optical PSF is independently characterised, as this can severely impede the attainable resolution of a diagnostic measurement. A high quality laser and specially chosen optics have been used to generate an intense optical point source in order to accomplish such a characterisation. The point source was used to measure the PSFs of various electron-beam imaging systems. These systems incorporate a digital micro-mirror array, which was used to produce very high (>105) dynamic range images. The PSF was measured at each intermediary image plane of the optical system; enabling the origin of any perturbations to the PSF to be isolated and potentially mitigated. One of the characterised systems has been used for optical transition radiation (OTR) measurements of an electron beam at KEK-ATF2 (Tsukuba, Japan). This provided an application of this process to actively improve the resolution of the beam imaging system. Presented here are the results of our measurements and complementary simulations carried out using Zemax Optical Studio

High Resolution and Dynamic Range Characterisation of Beam Imaging Systems

Any imaging system requires the use of various optical components to transfer the light from the source, e.g. optical radiation generated by a charged particle beam, to the sensor. The impact of the transfer optics on the image resolution is often not well known. To improve this situation, the point spread function (PSF) of the optical system must be measured, preferably, with high dynamic range. For this purpose we have created an intense, small (~ 1 μm) point source using a high quality laser and special focusing optics; and introduced a digital micro-mirror array in the optical system to substantially increase its dynamic range. The PSFs of optical systems that are currently being developed for high resolution, high dynamic range beam imaging using optical transition and diffraction radiation are measured and compared to Zemax simulations. The goal of these studies is to systematically understand and mitigate any ill effects on the PSF due to aberrations, diffraction and misalignment of the components of the imaging system. We present the results of our measurements and simulations

Laserwire Emittance Scanner at CERN Linac 4

Linac 4 presently under construction at CERN is designed to replace the existing 50 MeV Linac 2 in the LHC injector chain and will accelerate the beam of high current negative hydrogen ions to 160 MeV. During the commissioning a laserwire emittance scanner has been installed allowing noninvasive measuring of the emittance at 3 MeV and 12 MeV setups. A low power infrared fibre coupled laser was focused in the interaction region down to ~150 um and collided with the ion beam neutralising negative ions. At each transverse laser position with respect to the ion beam the angular distribution of the neutral particle beamlets was recorded by scanning a diamond detector across the beamlet at a certain distance from the IP while the main beam of the H⁻ ions was deflected using dipole magnet installed upstream the detector. Measuring the profile of the beamlet by scanning the laser across the beam allows to directly measure the transverse phase-space distribution and reconstruct the transverse beam emittance. In this report we will describe the analysis of the data collected during the 3 MeV and 12 MeV operation of the Linac 4. We will discuss the hardware status and future plans

Status of the CLIC-UK R&D; Programme on Design of Key Systems for the Compact Linear Collider

Six UK institutes are engaged in a collaborative R&D; programme with CERN aimed at demonstrating key aspects of technology feasibility for the Compact Linear Collider (CLIC). We give an overview and status of the R&D; being done on: 1) Drive-beam components: quadrupole magnets and the beam phase feed-forward prototype. 2) Beam instrumentation: stripline and cavity beam position monitors, an electro-optical longitudinal bunch profile monitor, and laserwire and diffraction and transition radiation monitors for transverse beam-size determination. 3) Beam delivery system and machine-detector interface design, including beam feedback/control systems and crab cavity design and control. 4) RF structure design. In each case, where applicable, we report on the status of prototype systems and performance tests with beam at the CTF3, ATF2 and CesrTA test facilities, including plans for future experiments