The Laser Wakefield Acceleration (LWFA) has advanced the accelerating gradient many orders of magnitude over the conventional technologies. Their application to high energy accelerators has been ...considered, while a new field of micrometric accelerators appears for medical applications.
The Science and Technology of Particle Accelerators provides an accessible introduction to the field, and is suitable for advanced undergraduates, graduate students, and academics, as well as ...professionals in national laboratories and facilities, industry, and medicine who are designing or using particle accelerators. Providing integrated coverage of accelerator science and technology, this book presents the fundamental concepts alongside detailed engineering discussions and extensive practical guidance, including many numerical examples. For each topic, the authors provide a description of the physical principles, a guide to the practical application of those principles, and a discussion of how to design the components that allow the application to be realised. Features: Written by an interdisciplinary and highly respected team of physicists and engineers from the Cockcroft Institute of Accelerator Science and Technology in the UK Accessible style, with many numerical examples Contains an extensive set of problems, with fully worked solutions available Rob Appleby is an academic member of staff at the University of Manchester, and Chief Examiner in the Department of Physics and Astronomy. Graeme Burt is an academic member of staff at the University of Lancaster, and previous Director of Education at the Cockcroft Institute. James Clarke is head of Science Division in the Accelerator Science and Technology Centre at STFC Daresbury Laboratory. Hywel Owen is an academic member of staff at the University of Manchester, and Director of Education at the Cockcroft Institute. All authors are researchers within the Cockcroft Institute of Accelerator Science and Technology and have extensive experience in the design and construction of particle accelerators, including particle colliders, synchrotron radiation sources, free electron lasers, and medical and industrial accelerator systems.
Abstract
Multi-species ion acceleration from ultra-thin foils was studied experimentally, employing the Vulcan Petawatt laser at the Central Laser Facility, UK. Plastic (CH) foils with thicknesses in ...the range 10–340 nm were irradiated with intense, short (750 fs) laser pulses producing maximum energies of
∼
65
MeV and 25 MeV/nucleon obtained for H
+
and C
6+
ions, respectively. Ion spectra obtained from high resolution spectrometers suggest differences in the acceleration dynamics for the two species. Comparisons are made with two-dimensional Particle in Cell simulations, which identify, for an optimal thickness, two main mechanisms contributing to the ion acceleration process, namely multi-species target normal sheath acceleration (TNSA) and radiation pressure acceleration (RPA). Ion energies are further enhanced by the onset of relativistically induced transparency. A final stage in the acceleration is caused by the formation of electron jets (as the target undergoes transparency), which accelerate the ions off-axis. By analysing the spatial and temporal evolution of the accelerating fields, we are able to infer the effect of the different mechanisms on each species and how this translates to the experimental observations. The two main mechanisms, TNSA and RPA, are seen to each produce a distinct population of high energy protons whereas a single population of carbon is accelerated by a summation of these effects. This species-specific analysis sheds new light on the complex dynamics in a multi-species target expansion and on the contribution of different acceleration processes to the acceleration of the most energetic ions in the spectrum.
The estimation of the tyrearoad friction coefficient is fundamental for vehicle control systems. Tyre sensors enable the friction coefficient estimation based on signals extracted directly from ...tyres. This paper presents a tyrearoad friction coefficient estimation algorithm based on tyre lateral deflection obtained from lateral acceleration. The lateral acceleration is measured by wireless three-dimensional accelerometers embedded inside the tyres. The proposed algorithm first determines the contact patch using a radial acceleration profile. Then, the portion of the lateral acceleration profile, only inside the tyrearoad contact patch, is used to estimate the friction coefficient through a tyre brush model and a simple tyre model. The proposed strategy accounts for orientation-variation of accelerometer body frame during tyre rotation. The effectiveness and performance of the algorithm are demonstrated through finite element model simulations and experimental tests with small tyre slip angles on different road surface conditions.
An anelastic numerical model is used to explore the dynamics accompanying the attainment of large amplitudes by gravity waves (GWs) that are localized in altitude and time. GW momentum transport ...induces mean flow variations accompanying a GW packet that grows exponentially with altitude, is localized in altitude, and induces significant GW phase speed, and phase, variations across the GW packet. These variations arise because the GW occupies the region undergoing accelerations, with the induced phase speed variations referred to as “self‐acceleration.” Results presented here reveal that self‐acceleration of a GW packet localized in time and altitude ultimately leads to stalling of the vertical propagation of the GW packet and accompanying two‐ and three‐dimensional (2‐D and 3‐D) instabilities of the superposed GW and mean motion field. The altitudes at which these effects occur depend on the initial GW amplitude, intrinsic frequency, and degree of localization in time and altitude. Larger amplitudes and higher intrinsic frequencies yield strong self‐acceleration effects at lower altitudes, while smaller amplitudes yield similar effects at higher altitudes, provided the Reynolds number, Re, is sufficiently large. Three‐dimensional instabilities follow 2‐D “self‐acceleration instability” for sufficiently high Re. GW packets can also exhibit self‐acceleration dynamics at more than one altitude because of continued growth of the GW packet leading edge above the previous self‐acceleration event.
Key Points
Gravity wave self‐acceleration dynamics are common in the atmosphere
Self‐acceleration disrupts gravity wave vertical propagation
Self‐acceleration leads to instabilities and local momentum deposition
Energetic electrons have frequently been observed in small‐scale flux ropes. However, whether these energetic electrons were energized directly within the flux rope or not is unknown. In this paper, ...we present concrete evidence provided by the Magnetospheric Multiscale mission that a secondary flux rope provided strong acceleration for electrons expelled by the reconnection X line. We find that the energetic electron fluxes inside the ion‐scale flux rope were larger than those outside the flux rope. Electrons were adiabatically accelerated by betatron and Fermi mechanisms inside the flux rope. The highest energy electrons (>100 keV) were produced by betatron acceleration, whereas Fermi acceleration was unable to accelerate the electrons to high energy probably due to the finite distance of the acceleration region along the field‐aligned direction. These results confirm the essential role of ion‐scale flux ropes in producing energetic electrons.
Key Points
First quantitative evidence for adiabatic electron acceleration within ion‐scale flux rope
The most energetic electrons were produced by betatron acceleration inside the flux rope
The Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) aims at studying plasma wakefield generation and electron acceleration driven by proton bunches. It is a proof-of-principle ...R&D experiment at CERN and the world׳s first proton driven plasma wakefield acceleration experiment. The AWAKE experiment will be installed in the former CNGS facility and uses the 400GeV/c proton beam bunches from the SPS. The first experiments will focus on the self-modulation instability of the long (rms ~12cm) proton bunch in the plasma. These experiments are planned for the end of 2016. Later, in 2017/2018, low energy (~15MeV) electrons will be externally injected into the sample wakefields and be accelerated beyond 1GeV. The main goals of the experiment will be summarized. A summary of the AWAKE design and construction status will be presented.
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