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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 19 records

Precision Control of the Electron Longitudinal Bunch Shape Using an Emittance-Exchange Beam Line

We report on the experimental generation of relativistic electron bunches with a tunable longitudinal bunch shape. A longitudinal bunch-shaping (LBS) beam line, consisting of a transverse mask followed by a transverse-to-longitudinal emittance exchange (EEX) beam line, is used to tailor the longitudinal bunch shape (or current profile) of the electron bunch. The mask shapes the bunch’s horizontal profile, and the EEX beam line converts it to a corresponding longitudinal profile. The Argonne wakefield accelerator rf photoinjector delivers electron bunches into a LBS beamline to generate a variety of longitudinal bunch shapes. The quality of the longitudinal bunch shape is limited by various perturbations in the exchange process. We develop a simple method, based on the incident slope of the bunch, to significantly suppress the perturbations

Ha, G.↗

Redesigning the Jefferson Lab Hall A beam line for high precision parity experiments

The Continuous Electron Beam Accelerator Facility (CEBAF) was built with a thermionic electron source and the three original experimental hall lines reflected this. A few years after beam delivery began a parity violation experiment was approved and two polarimeters were installed in the Hall A beam line. The beam raster system was placed after the new Compton polarimeter, before one accelerator quadrupole and four quadrupoles in the new Moller polarimeter. It was very difficult to meet experimental requirements on envelope functions and raster shape with this arrangement so a sixth quadrupole was installed downstream of the Moller polarimeter to provide an additional degree of freedome. All of the parity experiments in Hall A have been run with this still-unsatisfactory configuration. The MOLLER experiment is predicated on achieving a 2% error on a 32 ppb asymmetry. Beam line changes are required to meet the systematic error budget. This work documents the existing beam line, an interim change which can be accomplished during a annual maintenance down, and the final configuration for MOLLER and subsequent experiments.

47 OTHER INSTRUMENTATION↗

Energy Deposition, Radiological and Thermal Studies for Linac-to-Booster Transfer Line Beam Absorber

The PIP-II Linac-to-Booster transfer line will transport the beam from the end of the superconducting Linac to the Injection Girder of the Booster. The transfer line consists of two arcs and a straight section in between (see Fig. 1). The straight section splits into two separate lines: Beam Absorber and Mu2e experiment lines. In this paper, results of energy deposition studies for the Beam Absorber, performed with MARS15 Monte Carlo code for normal operation, are presented. Also, corresponding thermal analyses with ANSYS code are described. According to PIP-II design parameters, the beam energy as high as 1 GeV is considered. Two beam power options were studied: (i) 50 kW as a conservative estimate for a permanent absorber; (ii) 5 kW as an option for a portable absorber required for a commissioning stage.

43 PARTICLE ACCELERATORS↗

The dipole corrector magnets for the FFAG beam line of the CBETA accelerator

The Cornell Brookhaven Experimental Test Reactor (CBETA) is a novel, and the first of its kind accelerator to combine two remarkable concepts, the Energy Recovery Linac (ERL) and the Fixed Field Alternating Gradient (FFAG) concept. The accelerator has been built at Cornell University in collaboration with Brookhaven National Laboratory (BNL) and it is at its commissioning stage. The FFAG beam line consist of two arcs sections and a straight section, with all sections comprised of single cells, each cell made of two Halback type of magnets. The cell in the arc consists of one focusing quadrupole and a combined function magnet which is comprised of a dipole and a defocusing quadrupole multipole. The cells in the straight section consist of a focusing and a defocusing quadrupoles. Each focusing quadrupole has a window-frame dipole corrector magnet generating vertical dipole field and the other magnet has a corrector generating horizontal dipole field. This technical note reports on the mechanical design and the electromagnetic properties of these window frame corrector magnets.

43 PARTICLE ACCELERATORS↗

Double Emittance Exchanger as a Bunch Compressor for the MaRIE XFEL electron beam line at 1GeV

We demonstrate an alternative realization of a bunch compressor (specifically the second bunch compressor for the MaRIE XFEL beamline, 1GeV electron energy) using a double emittance exchanger (EEX) and a telescope in the transverse phase space.We compare our results with a traditional bunch compressor realized via chicane, taking into account the nonlinear dynamics, Coherent Synchrotron Radiation (CSR) and Space Charge (SC) effects. In particular, we use the Elegant code for tracking particles through the beam line and analyze the eigen-emittances evolution to separate the influence of the CSR/SC effects from the nonlinear dynamics effects. We optimize the scheme parameters to reach a desirable compression factor and minimize the emittance growth. We observe dominant CSR-effects in our scheme resulting in critical emittance growth and introduce alternative version of an emittance exchanger with a reduced number of bending magnets to minimize the impact of CSR effects.

43 PARTICLE ACCELERATORS↗

Optics and Systems Design of the Ring-to-Second Target Transport Beam-Line for the SNS Second Target Station

The Second Target Station (STS) project at the Spallation Neutron Source (SNS) is being developed to provide world-leading cold neutron brightness for next-generation neutron scattering experiments. The STS Accelerator Systems (AS) scope includes the design and implementation of the Ring-to-Second Target (RTST) proton beam transport line, which extracts 1.3 GeV proton beam pulses from the existing Ring-to-Beam Transport (RTBT) system and delivers them to the STS target. The RTST design emphasizes operational reliability [high reliability], low activation [minimum activation of components and the tunnel], maintainability, and compatibility with existing SNS infrastructure through extensive reuse of proven RTBT systems and components. The beamline includes a new extraction region, a transport lattice consisting of dipole, quadrupole, and corrector magnets, beam instrumentation systems, vacuum systems, personnel protection systems, and radiation shielding systems. Beam optics and particle tracking studies were performed using PyORBIT to validate extraction trajectories, beam transport, and target beam spot requirements [60–90 cm² beam spot area]. This paper presents the optics design philosophy, extraction system architecture, transport lattice design, instrumentation strategy, vacuum system approach, and radiation protection integration for the RTST beamline. Particle tracking simulations indicate successful beam transport without beam loss under nominal operating conditions. The RTST is designed to transport 1.3 GeV proton beam pulses at repetition rates up to 15 Hz, delivering nominal beam power of 700 kW to the Second Target Station.

Baron, Alex [ORNL]↗

Optimizing the UED beam line design via ImpactT simulation

The high charge low energy compressor system developed at NSLS-II can generate 5MeV electron bunches with 50pC charge (10 -8 electrons) focusing to 30 micron beam size and bunch length of order of 100 fs. NSLS-II plans to build it as part of the existing instrument for the ultra-fast electron diffraction (UED) and ultra-fast electron microscope (UEM) experiments to be installed at ATF-II, BNL. The expected intensity will be several orders of magnitudes higher than achieved previously using current technology (~10 -4 -10 -5 electrons). This type of accelerator based MeV electron microscopes, taking advantage of strong interaction of electrons with matter and overcoming space charge problem, are complementary to XFEL, such as LCLS.

36 MATERIALS SCIENCE↗

Testing of 90° beam-line prototype at 55 MeV electron linac

Argonne National Laboratory, in cooperation with NorthStar Medical Technologies and Los Alamos National Laboratory, is developing a technology for the production of Mo-99 via photonuclear reaction on a Mo-100 target. The new facility will utilize electron accelerators with high beam power.

07 ISOTOPE AND RADIATION SOURCES↗

Online multi-objective particle accelerator optimization of the AWAKE electron beam line for simultaneous emittance and orbit control

Multi-objective optimization is important for particle accelerators where various competing objectives must be satisfied routinely such as, for example, transverse emittance vs bunch length. We develop and demonstrate an online multi-time scale multi-objective optimization algorithm that performs real time feedback on particle accelerators. We demonstrate the ability to simultaneously minimize the emittance and maintain a reference trajectory of a beam in the electron beamline in CERN’s Advanced Proton Driven Plasma Wakefield Acceleration Experiment.

43 PARTICLE ACCELERATORS↗

Development and operation of a Pr 2 Fe 14 B based cryogenic permanent magnet undulator for a high spatial resolution x-ray beam line

Short period, high field undulators are used to produce hard x-rays on synchrotron radiation based storage ring facilities of intermediate energy and enable short wavelength free electron laser. Cryogenic permanent magnet undulators take benefit from improved magnetic properties of RE 2 Fe 14 B (Rare Earth based magnets) at low temperatures for achieving short period, high magnetic field and high coercivity. Using Pr 2 Fe 14 B instead of Nd 2 Fe 14 B, which is generally employed for undulators, avoids the limitation caused by the spin reorientation transition phenomenon, and simplifies the cooling system by allowing the working temperature of the undulator to be directly at the liquid nitrogen one (77 K). We describe here the development of a full scale (2 m), 18 mm period Pr 2 Fe 14 B cryogenic permanent magnet undulator (U18). The design, construction and optimization, as well as magnetic measurements and shimming at low temperature are presented. In conclusion, the commissioning and operation of the undulator with the electron beam and spectrum measurement using the Nanoscopmium beamline at SOLEIL are also reported.

43 PARTICLE ACCELERATORS↗

Magnetic and Thermal Design of HTS Quadrupole Magnet for Newly Developed Superconducting Proton Cyclotron Beam Line

A magnetic and thermal design of high-temperature superconducting (HTS) quadrupole magnet for newly developed superconducting proton cyclotron was presented in this research. With superconducting technology, the design can reduce the magnet size and remove the heat loads more efficiently. Calculations are conducted with finite element method (FEM) to study the quadrupole magnet’s magnetic and thermal properties. For the magnet cold-mass and cryostat system, the heat load is mainly generated by conduction and radiation. Multilayer thermal insulation and G10 supports are used to restrict them. The magnetic field distribution in the HTS coils is calculated to consider the critical current degradation of the YBCO tapes. The effects on the field gradient quality in relation to the pole tip profile and end chamfer are analyzed. The sixth multipole component in the integral field can be improved with end chamfer. Finally, a 20 T/m HTS quadrupole magnet with integral field uniformity less than 0.05% out to 75% of the inscribed radius is proposed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

X-ray Spectrometry in the Era of Aberration-Corrected Electron Optical Beam Lines

Abstract Aberration correction in the analytical transmission electron microscope is most closely associated with improvements in high-resolution imaging. In this paper, the combination of that technology with new system designs, which optimize both electron optics and x-ray detection, is shown to provide more than a tenfold increase in performance over the last 25 years.

Zaluzec, Nestor J. (ORCID:0000000248573487)↗