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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Design of a magnetic circuit for a cryogenic undulator in Taiwan photon source

The plan for beamlines in Phase II at Taiwan Photon Source is to construct two new BioSAXS and nano-ARPES beamlines. A highly brilliant light source can be produced with a cryogenic undulator, and many synchrotron facilities have been developed and operated with these in their storage rings. The development of a cryogenic undulator became a target for a light source in TPS phase II. A cryogenic undulator with period of length 15 mm will be made in a hybrid magnetic structure, and use PrFeB permanent-magnet materials. A maximum magnetic field 1.31 T is estimated at gap 4 mm and temperature about 100 K. The spectral performance of a TPS cryogenic undulator is presented in this paper.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Electron Motion in the Three-Dimensional Field of Undulator

In this paper we consider the motion of relativistic electrons in an ideal three-dimensional magnetic field of an undulator. The ideality of the magnetic field means that, on the undulator axis, the field is directed strictly vertically upward and has a strictly sinusoidal shape. In the overwhelming majority of cases, only this leading component of the field is taken into account in calculating the electron trajectory. In this paper, in the equations of motion of an electron in the magnetic field of an undulator, all three components of the field are taken into account, so that the undulator field under consideration satisfies the stationary Maxwell equations. In this case, the differential equations of motion of the electron are solved analytically with the help of perturbation theory, and not by the method of averaging over fast oscillations of the electron, as was done in a number of previous papers. These analytic expressions for trajectories describe the behavior of particles in the focusing magnetic field of an undulator much more completely. An analysis of these expressions shows that the behavior of electrons in such a three-dimensional field of the undulator is much more complicated than what follows from the equations obtained by the averaging method. In particular, there is a cross effect when changes in the initial vertical parameters of the electron trajectory cause changes in the horizontal component of its trajectory and vice versa. A comparison of the solutions obtained analytically with the results of numerical calculations of electron trajectories using the Runge–Kutta method demonstrates their high accuracy.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Negative-mass mitigation of Coulomb repulsion for terahertz undulator radiation of electron bunches

It is proposed to utilize the effect of negative mass for stabilization of the effective axial size of very dense and short electron bunches produced by photo-injector guns by using combined undulator and strong uniform magnetic fields. It has been shown that in the “abnormal” regime, an increase in the electron energy leads to a decrease in the axial velocity of the electron; due to the negative-mass effect, the Coulomb repulsion of electrons leads to their attraction and formation of a fairly stable and compact bunch “nucleus.” An undulator with a strong uniform magnetic field providing the negative-mass effect is designed for an experimental source of terahertz radiation. The use of the negative-mass regime in this experiment should result in a long-pulse coherent spontaneous undulator emission from a short dense moderately relativistic (5.5 MeV) photo-injector electron bunch with a high (up to 20%) efficiency and a narrow frequency spectrum.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Algorithms to automate gap-dependent integral tuning for the 2.8-meter long horizontal field undulator with a dynamic force compensation mechanism

A 2.8-meter long horizontal field prototype undulator with a dynamic force compensation mechanism has been developed and tested at the Advanced Photon Source (APS) at Argonne National Laboratory (Argonne). The magnetic tuning of the undulator integrals has been automated and accomplished by applying magnetic shims. A detailed description of the algorithms and performance is reported.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

The PETRA III extension

The 3{sup rd} generation low-emittance 6 GeV PETRA III facility has been substantially modified to add new beamlines. This extension project involved the complete removal and reconstruction of part of the storage ring with a double-bend achromat lattice as well as the construction of two new experimental halls. Making use of two long straight sections and a canted undulator scheme in the rebuilt arcs, up to ten new insertion device beamlines can be accommodated. In the current phase of the project, seven insertion device and one bending magnet beamline are being implemented.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Magnet system optimization for segmented adaptive-gap in-vacuum undulator

Segmented Adaptive Gap in-vacuum Undulator (SAGU), in which different segments have different gaps and periods, promises a considerable spectral performance gain over a conventional undulator with uniform gap and period. According to calculations, this gain can be comparable to the gain achievable with a superior undulator technology (e.g. a room-temperature in-vacuum hybrid SAGU would perform as a cryo-cooled hybrid in-vacuum undulator with uniform gap and period). However, for reaching the high spectral performance, SAGU magnetic design has to include compensation of kicks experienced by the electron beam at segment junctions because of different deflection parameter values in the segments. Here we show that such compensation to large extent can be accomplished by using a passive correction, however, simple correction coils are nevertheless required as well to reach perfect compensation over a whole SAGU tuning range. Magnetic optimizations performed with Radia code, and the resulting undulator radiation spectra calculated using SRW code, demonstrating a possibility of nearly perfect correction, are presented.

47 OTHER INSTRUMENTATION↗
DOE OSTI2016

Development of cryogenic undulators with PrFeB magnets at SOLEIL

Short period high field undulators are of interest for X-ray brilliance enhancement in synchrotron radiation applications and for compact Free Electron Lasers. Cryogenic in-vacuum undulators [1] are one of the possible solutions. At SOLEIL, PrFeB magnets were directly chosen, even if still under development at that time. Indeed, they enable to avoid the spin transition reorientation phenomenon which occurs with NdFeB magnets [2] and the magnets can be cooled down directly at 77 K. The first selected grade CR53 from Hitachi presents a remanence of 1.35 T at 293 K and 1.57 T at 77 K, with a coercivity of 1355 kA/m at 293 K and 6000 kA/m at 77 K. A 2 m long cryogenic undulator of period 18 mm was first built in-house, with a specific Hall probe bench directly installed in the final vacuum chamber. This first cryogenic undulator has been in operation on the storage ring for 4 years [3]. A second U18 cryo-ready undulator using a slightly different magnet grade with a higher coercivity and modules with magnets surrounded by two half poles for easier magnetic optimization is under construction. A third 3 m long cryo-ready undulator U15 with a period of 15 mm is under development. It will be first used for the LUNEX5 FEL [4, 5] project (COXINEL demonstration of FEL amplification with a laser wakefield acceleration [6]). The measurement bench will include a correction of the Hall probe position and angle, the field integrals will be measured with a stretched wire.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Conceptual design of front ends for the advanced photon source multi-bend achromats upgrade

The proposed Advanced Photon Source (APS) upgrade from a double-bend achromats (DBA) to multi-bend achromats (MBA) lattice with ring energy change from 7 GeV to 6 GeV and beam current from 100 mA to 200 mA poses new challenges for front ends. All front ends must be upgraded to fulfill the following requirements: 1) handle the high heat load from two insertion devices in either inline or canted configuration, 2) include a clearing magnet in the front end to deflect and dump any electrons in case the electrons escape from the storage ring during swap-out injection with the safety shutters open, 3) incorporate the next generation x-ray beam position monitors (XBPMs) into the front end to meet the new stringent beam stability requirements. This paper presents the evaluation of the existing APS front ends and standardizes the insertion device (ID) front ends into two types: one for the single beam and one for the canted beams. The conceptual design of high heat load front end (HHLFE) and canted undulator front end (CUFE) for APS MBA upgrade is presented.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

Generation of X-Ray Radiation in Free-Electron Lasers with Two-Frequency Undulators

The possibility of creating an x-ray laser with a two-frequency undulator with the help of the phenomenological model of a single-pass free-electron laser (FEL) that takes into account the beam characteristics and the undulator field is studied. The model is used to analyze the FEL dynamics, and the simulation results are compared with the experimental data. The advantages of using a two-frequency undulator in the single-pass FEL and the possibility of generating powerful x-ray radiation in it are demonstrated. The evolution of power of higher-harmonic generation in the FEL and the bunching coefficient at wavelengths of these harmonics are studied. The possibility of their further amplification until saturation in a cascade FEL matched to higher harmonics of the two-frequency undulator is demonstrated.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

Multicascade X-Ray Free-Electron Laser with Harmonic Multiplier and Two-Frequency Undulator

The feasibility of generation of powerful x-ray radiation by a cascade free-electron laser (FEL) with amplification of higher harmonics using a two-frequency undulator is studied. To analyze the FEL operation, a complex phenomenological single-pass FEL model is developed and used. It describes linear and nonlinear generation of harmonics in the FEL with seed laser that takes into account initial electron beam noise and describes all main losses of each harmonic in each FEL cascade. The model is also calibrated against and approved by the experimental FEL data and available results of three-dimensional numerical simulation. The electron beam in the undulator is assumed to be matched and focused, and the dynamics of power in the singlepass FEL with cascade harmonic multipliers is investigated to obtain x-ray laser radiation in the FEL having the shortest length, beam energy, and frequency of the seed laser as low as possible. In this context, the advantages of the two-frequency undulator used for generation of harmonics are demonstrated. The evolution of harmonics in a multicascade FEL with multiplication of harmonics is investigated. The operation of the cascade FEL at the wavelength λ = 1.14 nm, generating ~30 MW already on 38 m with the seed laser operating at a wavelength of 11.43 nm corresponding to the maximal reflectivity of the multilayered mirror MoRu/Be coating is investigated. In addition, the operation of the multicascade FEL with accessible seed UVlaser operating at a wavelength of 157 nm (F2 excimer UV-laser) and electron beam with energy of ~0.5 GeV is investigated. X-ray radiation simulated in it at the wavelength λ ~ 3.9 nm reaches power of ~50 MW already at ~27 m, which is by two orders of magnitude shorter than 3.4 km of the x-ray FEL recently put into operation in Europe.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

The analysis of Raman scattering in a free-electron laser with a rectangular hybrid wiggler

A one dimensional theory of the stimulated Raman backscattering process in a free electron laser with rectangular hybrid wiggler (RHW) is analyzed. The dispersion relation in the rest frame of the electron beam and also a formula for the lab-frame spatial growth rate are derived. A numerical computation of the growth rate for RHW is conducted and a comparison with that for coaxial hybrid wiggler is made away from the resonance. The growth rate is found larger for the rectangular wiggler than for the coaxial wiggler. A much narrower magnetoresonance associated with the third spatial harmonic is also obtained compared to the first one.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Compact scanning transmission x-ray microscope at the photon factory

We report the design and performance of a compact scanning transmission X-ray microscope developed at the Photon Factory. Piezo-driven linear stages are used as coarse stages of the microscope to realize excellent compactness, mobility, and vibrational and thermal stability. An X-ray beam with an intensity of ∼10{sup 7} photons/s was focused to a diameter of ∼40 nm at the sample. At the soft X-ray undulator beamline used with the microscope, a wide range of photon energies (250–1600 eV) is available. The microscope has been used to research energy materials and in environmental sciences.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Laser wakefield accelerated electron beam monitoring and control

We will discuss our participation in the ImPACT project, which has as one of its goals the development of an ultra-compact electron accelerator using lasers (< 1 GeV, < 10 m) and the generation of an x-ray beam from the accelerated electrons. Within this context we will discuss our investigation into electron beam monitoring and control. Since laser accelerated electrons will be used for x-ray beam generation combined with an undulator, we will present investigation into the possibilities of the improvement of electron beam emittance through cooling.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

The FERMI seeded-FEL facility: Status and perspectives

The FERMI Free Electron Laser (FEL) in Trieste, Italy operates in the extreme ultraviolet and soft x rays (EUV-SXR) wavelength range delivering high-fluence, stable, ultra-short pulses. Its unique design based on a seeded scheme and on tunable undulators allows unprecedented control of pulse parameters such as wavelength, phase, polarization, synchronization, pulse duration and implementation of multi-color FEL schemes. Both FEL-1 and FEL-2 lines with nominal wavelength range 100–20 nm and 20–4 nm, respectively, are open to users. We report on the unique features of FERMI, in particular those that have evolved beyond the original design, and on their application to pioneering experiments. We also present the upgrades that are planned to further expand the capabilities of this unique light source.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

FLASH2: Operation, beamlines, and photon diagnostics

FLASH2, a major extension of the soft X-ray free-electron laser FLASH at DESY, turns FLASH into a multi-user FEL facility. A new undulator line is located in a separate accelerator tunnel and driven additionally by the FLASH linear accelerator. First lasing of FLASH2 was achieved in August 2014 with simultaneous user operation at FLASH1. The new FLASH2 experimental hall offers space for up to six experimental end stations, some of which will be installed permanently. The wide wavelength range spans from 4-60 nm and 0.8 nm in the 5{sup th} harmonic and in the future deep into the water window in the fundamental. While this is of high interest to users, it is challenging from the beamline instrumentation point of view. Online diagnostics - which are mostly pulse resolved - for beam intensity, position, wavelength, wave front, and pulse length have been to a large extent developed at FLASH(1) and have now been optimized for FLASH2. Pump-probe facilities for XUV-XUV, XUV optical and XUV-THz experiments will complete the FLASH2 user facility.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

EPU correction scheme study at the CLS

The Canadian Light Source (CLS) Quantum Materials Spectroscopy Center (QMSC) beamline will employ a novel double period (55 mm, 180 mm) elliptically polarizing undulator (EPU) to produce photons of arbitrary polarization in the soft X-ray regime. The long period and high field of the 180 mm period EPU will have a strong dynamic focusing effect on the storage ring electron beam. We have considered two partial correction schemes, a 4 m long planar array of BESSY-II style current strips, and soft iron L-shims. In this paper we briefly consider the implementation of these correction schemes.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Properties of the insertion devices for PETRA III and its extension

DESY presently operates 14 independent insertion device (ID) beamlines at its 6 GeV storage ring PETRA III. Besides the 2 m long standard undulators U29 and U32, several special IDs of up to 5 m length have been installed to meet the experimental requests for high energy X-rays, elliptically polarized light, and a higher degree of coherence. Two additional half octants of the ring have recently been reconstructed, in order to extend the experimental capabilities at PETRA III. The straight sections also allow for installation of IDs of 2 m or 5 m length. This article gives an overview of the ID key parameters, the spectral properties and the brilliance of the current undulators installed at PETRA III. It also presents the characteristics of some of the upcoming special IDs, like in-vacuum and short undulators.

43 PARTICLE ACCELERATORS↗