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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
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Compact, high-efficiency accelerators driven by low-voltage solid-state amplifiers

A compact particle accelerator can include two or more cavities disposed along an axis of the particle accelerator, each of which is coupled to two or more drivers. The accelerator can also include a power supply coupled to the two or more drivers such that a particle beam traveling along the axis is accelerated. The power supply can be an interface with a commercial power outlet, battery power, or a combination thereof depending upon the use case. Example configurations of the accelerator include hand held or mobile devices that are capable of delivering up to and greater than a 1 MeV electron beam.

42 ENGINEERING↗
DOE OSTI2021

Compact, high-efficiency accelerators driven by low-voltage solid-state amplifiers

A compact particle accelerator can include two or more cavities disposed along an axis of the particle accelerator, each of which is coupled to two or more drivers. The accelerator can also include a power supply coupled to the two or more drivers such that a particle beam traveling along the axis is accelerated. The power supply can be an interface with a commercial power outlet, battery power, or a combination thereof depending upon the use case. Example configurations of the accelerator include hand held or mobile devices that are capable of delivering up to and greater than a 1 MeV electron beam.

Nguyen, Dinh Cong↗
DOE OSTI2018

High Gradient High Shunt Impedance Accelerating Structure

develop an inexpensive accelerating structure with a high gradient and high shunt impedance. Euclid Techlabs proposes to optimize this technology (based on a successful accelerating structure with distributed coupling developed at SLAC) for industrial applications and serial production. Future colliders require high gradient and high efficiency accelerating structures (high shunt impedance). The SLAC accelerator laboratory recently developed a series of accelerating structures with distributed coupling. Such a structure includes one or more parallel waveguides which are loaded by accelerating cavities. This approach allows configurations where no RF power is flowing axially through the accelerating cavity while maintaining a traveling RF wave through the cross-section of the accelerating structure. In this case the accelerating cavities are isolated at the beam pipe. Conventional traveling wave structures typically couple the RF power through the beam pipe. This feature constrains the cavity shunt impedance to relatively small values. For this reason, the distributed coupling design improves efficiency while reducing cost and improving the operational flexibility of particle accelerators. High gradient operation poses the risk of having a high breakdown rates. In traditional standing and traveling wave structures, RF power flows through the accelerating cells. For distributed coupling structures, this risk is reduced because the absence of power flow through the accelerating cavity allows configurations where no power flows through the beam pipe. Finally, the distributed coupling accelerating structure design allows fabricating structures in two halves. This significantly reduces the complexity of machining, brazing and tuning.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Low Cost High Efficiency Magnetrons for Accelerator Applications

High efficiency, low cost RF sources are required for proton, ion, and muon accelerators. These sources must be compact and provide precise control of the output power and phase. Currently only large, expensive klystrons can provide this performance. Calabazas Creek Research Inc. proposes to develop a phase locked magnetron-based system that has phase and amplitude control via a low power amplifier. The system uses phase modulation to control the RF power. The efficiency can exceed 80% and the cost is expected to be less than $3/Watt, significantly lower than other high power amplifiers. CCR originally proposed to develop a magnetron with a grid for control of phase and amplitude. Detailed simulations showed that this was not a promising approach. The grid was found to be viable only in magnetrons with low duty cycle, and amplitude control was demonstrated; but the grid was found to be not effective for phase locking. Attention was turned to a concept from Fermilab, which is very promising for both amplitude and phase control and does not require a grid. CCR will develop an RF system providing phase and amplitude control of a 100 kW peak, 10 kW average 1.3 GHz magnetron. Procedures and techniques will be applicable to design of systems at other frequencies and power levels. The program will include development of the magnetron and locking electronics. The system will be tested at Fermilab. Commercial Applications and Other Benefits Magnetrons can provide high levels of RF power at very high efficiency at low cost. As oscillators, however, their applications are limited. Magnetrons with more precise control of the output power and control of the phase could find wide application in accelerators and colliders. They would also provide improved performance for high resolution radar.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Positron acceleration in plasma wakefields

Plasma acceleration has emerged as a promising technology for future particle accelerators, particularly linear colliders. Significant progress has been made in recent decades toward high-efficiency and high-quality acceleration of electrons in plasmas. However, this progress does not generalize to the acceleration of positrons, as plasmas are inherently charge asymmetric. Here, we present a comprehensive review of historical and current efforts to accelerate positrons using plasma wakefields. Proposed schemes that aim to increase energy efficiency and beam quality are summarized and quantitatively compared. A dimensionless metric that scales with the luminosity-per-beam power is introduced, indicating that positron-acceleration schemes are currently below the ultimate requirement for colliders. The primary issue is electron motion; the high mobility of plasma electrons compared to plasma ions, which leads to nonuniform accelerating and focusing fields that degrade the beam quality of the positron bunch, particularly for high efficiency acceleration. Finally, we discuss possible mitigation strategies and directions for future research.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

Design of High Efficiency High Power Electron Accelerator Systems Based on Normal Conducting RF Technology for Energy and Environmental Applications

The goal of this project was to perform engineering design studies of three extremely high efficiency electron accelerators with the following parameters [1]: 2 MeV output beam energy and 1 MW average beam power; 10 MeV output energy and 10 MW; 10 MeV output energy and 1 MW. These linacs are intended for energy and environmental applications [2]. We based our designs on normal conducting radio-frequency technology. We have successfully reached this goal where we show rf-to-beam efficiency of 96.7 %, 97.2 %, and 79.6 % for these linacs.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Distributed coupling high efficiency linear accelerator

A microwave circuit for a linear accelerator includes multiple monolithic metallic cell plates stacked upon each other so that the beam axis passes vertically through a central acceleration cavity of each plate. Each plate has a directional coupler with coupling arms. A first coupling slot couples the directional coupler to an adjacent directional coupler of an adjacent cell plate, and a second coupling slot couples the directional coupler to the central acceleration cavity. Each directional coupler also has an iris protrusion spaced from corners joining the arms, a convex rounded corner at a first corner joining the arms, and a corner protrusion at a second corner joining the arms.

42 ENGINEERING↗
DOE OSTI2023

Status and future plans for C 3 R&D

C 3 is an opportunity to realize an e + e - collider for the study of the Higgs boson at √s = 250 GeV, with a well defined upgrade path to 550 GeV while staying on the same short facility footprint. C 3 is based on a fundamentally new approach to normal conducting linear accelerators that achieves both high gradient and high efficiency at relatively low cost. Given the advanced state of linear collider designs, the key system that requires technical maturation for C 3 is the main linac. This paper presents the staged approach towards a facility to demonstrate C 3 technology with both Direct (source and main linac) and Parallel (beam delivery, damping ring, ancillary component) R&D. The primary goal of the C 3 Demonstration R&D Plan is to reduce technical and cost risk by building and operating the key components of C 3 at an adequate scale. This R&D plan starts with the engineering design, and demonstration of one cryomodule and will culminate in the construction of a 3 cryomodule linac with pre-production prototypes. This R&D program would also demonstrate the linac rf fundamentals including achievable gradient and gradient stability over a full electron bunch train and breakdown rates. It will also investigate beam dynamics including energy spread, wakefields, and emittance growth. This work will be critical to confirm the suitability of the C 3 beam parameters for the physics reach and detector performance in preparation for a Conceptual Design Report (CDR), as well as for follow-on technology development and industrialization. The C 3 Demonstration R&D Plan will open up significant new scientific and technical opportunities based on development of high-gradient and high-efficiency accelerator technology. It will push this technology to operate both at the GeV scale and mature the technology to be reliable and provide high-brightness electron beams. The timeline for progressing with C 3 technology development will be governed by practical limitations on both the technical progress and resource availability. It consists of four stages: Stage 0) Ongoing fundamental R&D on structure prototypes, damping and vibrations. Stage 1) Advancing the engineering maturity of the design and developing start-to-end simulations including space-charge and wakefield effects. This stage will include testing of strucutres operating at cryogenic temperatures. Beam tests would be performed with high beam current to test full beam loading. Stage 2) Production and testing of the first cryomodule at cryogenic temperatures. This would provide sufficient experimental data to compile a CDR and it is anticipated for Stage 2 to last 3 years and to culminate with the transport of photo-electrons through the first cryomodule. Stage 3) Updates to the engineering design of the cryomodules, production of the second and third cryomodule and their installation. Lower charge and lower emittance beams will be used to investigate emittance growth. The successful full demonstration of the 3 cryomodules to deliver up to a 3 GeV beam and achieve the C 3 five gradient will allow a comprehensive and robust evaluation of the technical design of C 3 as well as mitigate technical, schedule, and cost risks required to proceed with a Technical Design Report (TDR).

radiation hardened magnets↗
DOE OSTI2021

High Efficiency Uniform Wakefield Acceleration of a Positron Beam Using Stable Asymmetric Mode in a Hollow Channel Plasma

Plasma wakefield acceleration in the blowout regime is particularly promising for high-energy acceleration of electron beams because of its potential to simultaneously provide large acceleration gradients and high energy transfer efficiency while maintaining excellent beam quality. However, no equivalent regime for positron acceleration in plasma wakes has been discovered to date. We show that after a short propagation distance, an asymmetric electron beam drives a stable wakefield in a hollow plasma channel that can be both accelerating and focusing for a positron beam. A high charge positron bunch placed at a suitable distance behind the drive bunch can beam-load or flatten the longitudinal wakefield and enhance the transverse focusing force, leading to high efficiency and narrow energy spread acceleration of the positrons. Three-dimensional quasistatic particle-in-cell simulations show that an over 30% energy extraction efficiency from the wake to the positrons and a 1% level energy spread can be simultaneously obtained. Further optimization is feasible.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

Online accelerator optimization with a machine learning-based stochastic algorithm

Abstract Online optimization is critical for realizing the design performance of accelerators. Highly efficient stochastic optimization algorithms are needed for many online accelerator optimization problems in order to find the global optimum in the non-linear, coupled parameter space. In this study, we propose to use the multi-generation Gaussian process optimizer for online accelerator optimization and demonstrate that the algorithm is significantly more efficient than other stochastic algorithms that are commonly used in the accelerator community.

Zhang, Zhe (ORCID:0000000281430381)↗
DOE OSTI2016

Self-mapping the longitudinal field structure of a nonlinear plasma accelerator cavity

The preservation of emittance of the accelerating beam is the next challenge for plasma-based accelerators envisioned for future light sources and colliders. The field structure of a highly nonlinear plasma wake is potentially suitable for this purpose but has not been yet measured. Here we show that the longitudinal variation of the fields in a nonlinear plasma wakefield accelerator cavity produced by a relativistic electron bunch can be mapped using the bunch itself as a probe. We find that, for much of the cavity that is devoid of plasma electrons, the transverse force is constant longitudinally to within ±3% (r.m.s.). Moreover, comparison of experimental data and simulations has resulted in mapping of the longitudinal electric field of the unloaded wake up to 83 GV m –1 to a similar degree of accuracy. Lastly, these results bode well for high-gradient, high-efficiency acceleration of electron bunches while preserving their emittance in such a cavity.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Magnetron R&D for high efficiency CW RF sources for industrial accelerators

The scheme of using high-efficiency magnetrons to drive radiofrequency accelerators has been demonstrated at 2450 MHz in CW mode *. Magnetron test stands at JLab and GA have been set up to further test the noise figure and the locking speed of the injection phase-lock method. For higher power applications, power combining experiments using a TM010 cavity-type combiner and a magic tee for the binary combiner while using a single clean injection signal has been carried out at 2450 MHz. The frequency pulling effect between the magnetron and a low-Q cavity has been shown to enhance the frequency locking bandwidth compared to the injection phase-lock alone. The principle has been studied by the equivalent circuit simulation, analytical model, and finally confirmed experimentally on the magnetrons. Due to the pandemic delay in 2020, the equivalent high power tests using a 75kW, 915MHz industrial magnetron will be done in 2021 and will be reported in a future paper.

Wang, H.↗
DOE OSTI2022

Magnetron R&D Progress for High Efficiency CW RF Sources of Industrial Accelerators

After the demonstration of using high efficiency magnetron power to combine and aim to drive a radio frequency accelerator at 2450MHz in CW mode [1], we have used trim coils adding to a water-cooled magnetron and three amplitude modulation methods in an open-loop control to further suppress the 120Hz side-band noise to -46.7dBc level. We have also successfully demonstrated the phase-locking to an industrial grade cooking magnetron transmitter at 915MHz with a 75kW CW power delivered to a water load by using a -26.6dBc injection signal. The sideband noise at 360Hz from the 3-Phase SCRs DC power supply can be reduced to -16.2dBc level. Their power combing scheme and higher power application to industrial accelerators are foreseeing.

Wang, H.↗