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In this paper, we simply outline the present status of the free electron laser and the laser plasma based accelerator, and we simply discuss the potential possible roads appearing in the accelerator community to use the laser plasma based accelerator into the field of the free electron laser.
We present diffraction patterns from micron-sized areas of mono-crystalline graphite obtained with an ultracold and ultrafast electron source. We show that high spatial coherence is manifest in the visibility of the patterns even for picosecond bunches of appreciable charge, enabled by the extremely low source temperature (~ 10 K). For a larger, ~ 100 um spot size on the sample, spatial coherence lengths > 10 nm result, sufficient to resolve diffraction patterns of complex protein crystals. This makes the source ideal for ultrafast electron diffraction of complex macromolecular structures such as membrane proteins, in a regime unattainable by conventional photocathode sources. By further reducing the source size, sub-um spot sizes on the sample become possible with spatial coherence lengths exceeding 1 nm, enabling ultrafast nano-diffraction for material science.
In this study, a low energy beam transport (LEBT) channel for the proton linac section of the Turkish Accelerator Center (TAC) has been designed by using TRAVEL code. Commonly used LEBT including two focusing solenoid magnets will transport and match the H- beam from a volume source to RFQ. In the beam dynamics simulations of such a LEBT line, 95% space-charge compensation (SCC) has been considered in this study. We aimed to find out the determination of our RFQ input parameters that gives the best possible beam quality at the entrance of the RFQ using beam collimator in the LEBT line as an alternative way. In this way, we have acquired the best possible beam quality on RFQ input plane as well as optimizing the LEBT line.
In the previous canonical formulation of beam dynamics for an electron bunch moving ultrarelativistically through magnetic bending systems, we have shown that the transverse dynamics equation for a particle in the bunch has a driving term which behaves as the centrifugal force caused by the particle's initial potential energy due to collective particle interactions within the bunch. As a result, the initial potential energy at the entrance of a bending system, which we call pseudo (kinetic) energy, is indistinguishable from the usual kinetic energy offset from the design energy in its perturbation to particle optics through dispersion and momentum compaction. In this paper, in identifying this centrifugal force on particles as the remnant of the CSR cancellation effect in transverse particle dynamics, we show how the dynamics equation in terms of the canonical momentum for beam motion on a curved orbit is related to the Panofsky-Wenzel theorem for wakefields for beam motion on a straight path. It is shown that the effect of pseudo energy spread can be measurable only for a high-peak-current bunch when the pseudo slice energy spread is appreciable compared to the slice kinetic energy spread. The implication of the pseudo slice energy spread for bunch dynamics in magnetic bends is discussed.
Hefei Light Source (HLS) is being upgraded to HLS II. Its emittance will be much lower than before, therefore the Touschek scattering will increase significantly and become the dominant factor of beam loss. So it is necessary to build a new beam loss monitoring (BLM) system differed from the old one to obtain the quantity and position information of lost electrons. This information is useful in the commissioning, troubleshooting and beam lifetime studying for HLS II. This paper analyzes the distribution features of different kinds of lost electrons, introduces the new machine's operation parameters and discusses the way to choose proper monitoring positions. Base on these comprehensive analysis, a new BLM system for HLS II is proposed.
First computer experiment results on proton beam deflection by the crystal miscut surface are presented. The phenomenology of proton channeling and quasichanneling has been applied to describe new features of the beam deflection. The analysis predicts efficient beam deflection by the acute crystal end due to repelling miscut potential.
These reports present the results of the 2013 Community Summer Study of the APS Division of Particles and Fields ("Snowmass 2013") on the future program of particle physics in the U.S. Chapter 6, on Accelerator Capabilities, discusses the future progress of accelerator technology, including issues for high-energy hadron and lepton colliders, high-intensity beams, electron-ion colliders, and necessary R&D for future accelerator technologies.
These reports present the results of the 2013 Community Summer Study of the APS Division of Particles and Fields ("Snowmass 2013") on the future program of particle physics in the U.S. Chapter 9, on Computing, discusses the computing challenges for future experiments in the Energy, Intensity, and Cosmic Frontiers, for accelerator science, and for particle theory, as well as structural issues in supporting the intense uses of computing required in all areas of particle physics.
Time-resolved beam parameters measurement system can be achieve electron beam energy in LIA. In this paper introduce work principle and method of time-resolved beam parameters measurement system. Show the experiment layout of energy measuring. The principle of magnetic analyzer was described, with the bending radius of 300 mm and the bending angle of 60 degree after hard-edge approximation, The measured energy is about 18MeV, the maximum energy variation is 2%.
The Landau-Lifshitz equation provides an efficient way to account for the effects of radiation reaction without acquiring the non-physical solutions typical for the Lorentz-Abraham-Dirac equation. We solve the Landau-Lifshitz equation in its covariant four-vector form in order to control both the energy and momentum of radiating particle. Our study reveals that implicit time-symmetric collocation methods of the Runge-Kutta-Nyström type are superior in both accuracy and better maintaining the mass-shell condition than their explicit counterparts. We carry out an extensive study of numerical accuracy by comparing the analytical and numerical solutions of the Landau-Lifshitz equation. Finally, we present the results of simulation of particles scattering by a focused laser pulse. Due to radiation reaction, particles are less capable for penetration into the focal region, as compared to the case of radiation reaction neglected. Our results are important for designing the forthcoming experiments with high intensity laser fields.
Muon colliders have been proposed for the next generation of particle accelerators that study high-energy physics at the energy and intensity frontiers. In this paper we study a possible implementation of muon ionization cooling, Parametric-resonance Ionization Cooling (PIC), in the twin helix channel. The resonant cooling method of PIC offers the potential to reduce emittance beyond that achievable with ionization cooling with ordinary magnetic focusing. We examine optimization of a variety of parameters, study the nonlinear dynamics in the twin helix channel and consider possible methods of aberration correction.
Acceleration of electrically charged bodies is carried out by the electric field running via the spiral structure of the electric pulse. The accelerated particles have a cylindrical shape with a diameter of cylinder two millimeters, a length of the conical part thirteen millimeters and the total length three hundred millimeters. Pre-acceleration of the cylinder up to speed one kilometer per second is performed by gas-dynamic. The pulse with the voltage amplitude two megavolts and the power three hundreds megawatts goes into the spiral waveguide synchronously with the rod injected onto it. The rod is accelerated by the traveling pulse in the longitudinal direction up to the finite velocity six kilometers per second for length three hundreds meters.
Using the method of small signal analysis, we study the application potential of relativistic electron beams in split-cavity oscillators (SCO's). A beam-energy change in the SCO as a function of the initial energy of a relativistic beam is considered. It is shown that the small-signal analysis method enables adequate evaluation of SCO parameters needed for effective modulation of a relativistic beam in a split cavity and for HPM generation using SCO's. The range of energies is found for which the effect of self-modulation of the beam density in SCO structures is most pronounced. It is also shown that for beam currents at which the space charge has little effect on the motion of electrons in a beam, the beam in a split-cavity oscillator is effectively self-modulated at beam energies less than ~300-400 keV. The self-modulation drops sharply in the range of energies from 250 to 400 keV, but as the beam current is increased, the effective beam self-modulation becomes appreciable in this range too, as well as even in a higher energy range.
The measurement of properties of exotic nuclei, essential for fundamental nuclear physics, now confronts a formidable challenge for contemporary radiofrequency accelerator technology. A promising option can be found in the combination of state-of-the-art high-intensity short pulse laser system and nuclear measurement techniques. We propose a novel Laser-driven Exotic Nuclei extraction-acceleration method (LENex): a femtosecond petawatt laser, irradiating a target bombarded by an external ion beam, extracts from the target and accelerates to few GeV highly-charged nuclear reaction products. Here a proof-of-principle experiment of LENex is presented: a few hundred-terawatt laser focused onto an aluminum foil, with a small amount of iron simulating nuclear reaction products, extracts almost fully stripped iron nuclei and accelerate them up to 0.9 GeV. Our experiments and numerical simulations show that short-lived, heavy exotic nuclei, with a much larger charge-to-mass ratio than in conventional technology, can be obtained in the form of an energetic, low-emittance, high-current beam.
Suggestions have been made for a 80-100 km circumference Future Circular Collider (FCC) that could ultimately contain a circular e+e- ring collider operating as a Higgs Factory as well as a 100 TeV hadron collider. Those suggestions have motivated us to propose an approach in which the project is sited at the location at the SSC tunnel, which has the lowest tunnel cost ever. The low tunnel cost would make it cost-effective to locate the 100 TeV Hadron Collider in a 270 km circumference tunne, using 4.5 Tesla superconducting magnets. The SSC tunnel itself would be used to house the Higgs Factory and the injector for the Hadron Collider. The injector for the Higgs Factory would be also used as a driver for an X-ray Free Electron Laser with unique capabilities for protein crystallography. The location of the project at a location with favorable geotechnology for minimum-cost tunneling, and low-cost/low-risk technology for the SRF and superconducting magnets, open the possibility to build the proposed laboratory within a decade.
We put forward a method to optimize the step-tapering amplitude of undulator strength and initial energy detuning of electron beam with the goal of maximizing the saturation power of high-gain FELs, based on the physics of longitudinal electron beam phase space. Using the FEL simulation code GENESIS, we numerically demonstrate the accuracy of the estimation for parameters corresponding to the linac coherent light source and the Tesla test facility.
Synchronized, independently tunable and focused $μ$J-class laser pulses are used to release multiple electron populations via photo-ionization inside an electron-beam driven plasma wave. By varying the laser foci in the laboratory frame and the position of the underdense photocathodes in the co-moving frame, the delays between the produced bunches and their energies are adjusted. The resulting multibunches have ultra-high quality and brightness, allowing for hitherto impossible bunch configurations such as spatially overlapping bunch populations with strictly separated energies, which opens up a new regime for light sources such as free-electron-lasers.
Beam quality preservation during transport of high-brightness electron beams is of general concern in the design of modern accelerators. Methods to manage incoherent synchrotron radiation (ISR) have been in place for decades; as beam brightness has improved coherent synchrotron radiation (CSR) and the microbunching instability (uBI) have emerged as performance limitations. We apply the compensation analysis of diMitri, Cornacchia, and Spampinati - as previously used by Borland - to the design of transport systems for use with low-emittance beams, and find that appropriately configured second order achromats will suppress transverse emittance growth due to CSR and appear to limit uBI gain.