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Douglas, David

Publications and source records attributed to Douglas, David.

8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Design and operation of a windowless gas target internal to a solenoidal magnet for use with a megawatt electron beam

A windowless hydrogen gas target of nominal thickness 10 19 cm -2 is an essential component of the DarkLight experiment, which is designed to utilize the megawatt electron beam at an Energy Recovery Linac (ERL). The design of such a target is challenging because the pressure drops by many orders of magnitude between the central, high-density section of the target and the surrounding beamline, resulting in laminar, transitional, and finally molecular flow regimes. The target system was assembled and operated at Jefferson Lab’s Low Energy Recirculator Facility (LERF) in 2016, and subsequently underwent several revisions and calibration tests at MIT Bates in 2017. The system at dynamic equilibrium was simulated in COMSOL to provide a better understanding of its optimal operation at other working points. We have determined that a windowless gas target with sufficiently high density for DarkLight’s experimental needs is feasible in an ERL environment.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

Synthesizing radioisotopes using an energy recovery linac

An apparatus and method for the production of radioisotopes utilizing an energy recovery linac. The ERL system is composed of an electron beam source, multiple superconducting radio frequency cavities operating at 4.5 K, a thin radiator, a target material, and a beam dump. The accompanying method discloses the use of the ERL system to generate desired radioisotopes via target interaction with bremsstrahlung photons while allowing recovery of a substantial portion of the electron beam energy before the beam is extracted to the beam dump.

Areti, Hari↗
DOE OSTI2015

Control of Coherent Synchrotron Radiation Effects During Recirculation with Bunch Compression

Studies of beam quality preservation during recirculation* have been extended to generate a design of an arc providing bunch compression with positive momentum compaction** and control of both incoherent and coherent synchrotron radiation (ISR and CSR) effects using the optics balance methods of diMitri et al.+. In addition, the arc/compressor generates very little micro-bunching gain. We detail the beam dynamical basis for the design, discuss the design process, give an example solution, and provide simulations of ISR and CSR effects. Reference will be made to a complete analysis of micro-bunching effects++. * D. Douglas et al., these proceedings ** S. Benson et al., these proceedings + S. diMitri et al., Phys. Rev. Lett. 110, 014801, 2 January 2013 ++ C.Y. Tsai et al., these proceedings This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.

Douglas, David↗
DOE OSTI2015

CONTROL OF SYNCHROTRON RADIATION EFFECTS DURING RECIRCULATION

We use results by Di Mitri et al. [1] as the basis of a method for suppression of synchrotron-radiation-driven beam quality degradation during recirculation. Use of second-order achromatic superperiodic recirculation transport based on individually isochronous and achromatic superperiods of low-quantum-excitation lattices is found to provide control of both emittance degradation from coherent synchrotron radiation (CSR) and microbunching instability (?BI) gain. Use of such low excitation lattices and choice of sufficiently large bend radius also insures incoherent synchrotron radiation (ISR) driven effects are well-managed.

Douglas, David↗
DOE OSTI2015

ELECTRON COOLING STUDY FOR MEIC

Electron cooling of the ion beams is one critical R&D to achieve high luminosities in JLab?s MEIC proposal. In the present MEIC design, a multi-staged cooling scheme is adapted, which includes DC electron cooling in the booster ring and bunched beam electron cooling in the collider ring at both the injection energy and the collision energy. We explored the feasibility of using both magnetized and non-magnetized electron beam for cooling, and concluded that a magnetized electron beam is necessary. Electron cooling simulation results for the newly updated MEIC design is also presented.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Coherent Synchrotron Radiation in Energy Recovery Linacs

Collective beam effects, including coherent synchrotron radiation (CSR), have been studied on free-electron lasers (FELs). Here we will discuss a particular case of the CSR effects, that in energy-recovery linacs (ERLs). Special consideration is given to these machines because of their high average beam power and the architecture of the machine for energy recovery forces extreme bends. A recent study conducted on the JLab IR FEL looked at how CSR impacts both average energy and the energy spectrum of the beam. Such studies are important, both broadly, to the understanding of CSR and more specifically for a number of proposed ERL projects. A few proposed examples include the MEIC bunched beam cooler ERL design and ERL FELs for potential lithography purposes that would operate in the EUV range.

Douglas, David↗
DOE OSTI2015

Control of synchrotron radiation effects during recirculation with bunch compression

Studies of beam quality during recirculation have been extended to an arc providing bunch compression with positive momentum compaction. It controls both incoherent and coherent synchrotron radiation (ISR and CSR) using methods including optics balance and generates little microbunching gain. We detail the dynamical basis for the design, discuss the design process, give an example, and provide simulations of ISR and CSR effects. Reference will be made to a complete analysis of microbunching effects.

43 PARTICLE ACCELERATORS↗