A5051590080- Particle accelerators and beam dynamics
- Particle Accelerators and Free-Electron Lasers
- Laser Design and Applications
- Laser-induced spectroscopy and plasma
- Gyrotron and Vacuum Electronics Research
- Laser-Plasma Interactions and Diagnostics
- Plasma Diagnostics and Applications
- Atomic and Molecular Physics
- Photocathodes and Microchannel Plates
- Magnetic confinement fusion research
- Laser-Matter Interactions and Applications
- Pulsed Power Technology Applications
- Advanced Optical Sensing Technologies
- Superconducting Materials and Applications
- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Methane Hydrates and Related Phenomena
- Electron and X-Ray Spectroscopy Techniques
- Solid State Laser Technologies
- Semiconductor Lasers and Optical Devices
- Advanced Surface Polishing Techniques
- Advanced Fiber Laser Technologies
- Experimental Learning in Engineering
- Optical Systems and Laser Technology
- Light effects on plants
United States Naval Research Laboratory
2007-2024
United States Navy
2024
FM Technologies (United States)
1998-2003
University of Maryland, College Park
1986-2002
Thomas Jefferson National Accelerator Facility
1996-2002
Continuous Electron Beam Accelerator Facility
1996
It has long been recognized that broadband laser light the potential to control parametric instabilities in inertial-confinement-fusion (ICF) plasmas. Here, we use results from laser-plasma-interaction simulations estimate bandwidth requirements for mitigating three predominant classes of direct-drive ICF implosions: cross-beam energy transfer (CBET), two-plasmon decay (TPD), and stimulated Raman scattering (SRS). We find frequency-tripled, Nd:glass light, a 8.5 THz can significantly...
Laser fusion researchers have realized since the 1970s that deep UV light from excimer lasers would be an advantage as a driver for robust high-performance capsule implosions inertial confinement (ICF). Most of this research has centered on krypton-fluoride (KrF) laser. In article we review advantages KrF laser direct-drive ICF, history high-energy development, and present state art describe development path to performance needed its energy application. We include descriptions architecture...
Stimulated rotational Raman scattering (SRRS) in the ultraviolet region (λ=248 nm) has been observed at Nike laser over extended propagation paths air during high power operation. Although this phenomenon is not significant for standard operating configurations Nike, broadening of spectrum and far-field focal profiles once intensity-path length product exceeds a threshold approximately 1 TW/cm. This paper presents experimental results new theoretical evaluation these effects. The...
The scattering of laser light due to cross-beam energy transfer (CBET) is an undesirable process in direct-drive inertial confinement fusion (ICF) that degrades both the compression and symmetry imploding target. Here, we present results from laser-plasma interaction simulations performed with wave-based code LPSE explore two techniques for suppressing CBET frequency-tripled, Nd:glass beams crossing a transonic plasma: a.) frequency detuning using or three discrete "colors" narrowband light;...
An experiment was designed to check theoretical predictions of charge homogenization and emittance growth in nonuniform space-charge-dominated beams due conversion field energy into transverse kinetic energy. Five beamlets were masked out a solid 5-keV electron beam injected periodic solenoidal focusing channel. Phosphor screen images showed that the merged an almost uniform density single beam. Images five-beamlet configuration observed at distance 7-8 lens periods. Experimental results on...
In direct drive inertial confinement laser fusion, a pellet containing D-T fuel is imploded by ablation arising from absorption of energy at its outer surface. For optimal coupling, the focal spot would continuously decrease to match reduction in pellet's diameter, thereby minimizing wasted energy. A krypton-fluoride (λ = 248 nm) that incorporates beam smoothing induced spatial incoherence has ability produce high quality profile whose diameter varies with time, property known as zooming....
The homogenization of a beam with transversely nonuniform initial density distribution is examined by masking the ouput from Pierce electron gun into five parallel beamlets, which are then propagated down channel periodically spaced solenoid focusing magnets. Experimental measurements, theoretical predictions, and PIC simulations in excellent agreement for averaged quantities such as rms emittance envelope radius. In addition, fine-structure characteristic nonlinear evolution beam, including...
The University of Maryland Electron Ring (UMER), currently under construction, has been designed to study the physics space-charge dominated beams at extremely large values betatron tune shift which exceed those existing strong-focusing synchrotrons and rings by more than an order magnitude. In this paper, unique design features research facility, new beam be investigated, recent experimental results in injector prototype as well simulation studies are reviewed.
A variable-perveance gridded electron gun has been designed, constructed, and extensively tested. The can produce a 2.5-kV, 40-mA, 50-ns fast beam pulse with good beam-optical properties. extremely flexible design features be operated in wide range of parameters the maximum energy up to 10 kV current hundreds milliamperes. perveance changed by adjusting A-K gap grid-cathode voltage maintain optimum properties.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML"...
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation J. L. Weaver, Oh, Phillips, B. Afeyan, Seely, D. Kehne, C. M. Brown, S. P. Obenschain, V. Serlin, A. Schmitt, U. Feldman, R. H. Lehmberg, E. Mclean, Manka; Observation of parametric instabilities in the quarter critical density region driven by Nike KrF laser. Physics Plasmas 1 February 2013; 20 (2): 022701....
Deleterious effects of laser-plasma instability (LPI) may limit the maximum laser irradiation that can be used for inertial confinement fusion. The short wavelength (248nm), large bandwidth, and very uniform illumination available with krypton-fluoride (KrF) lasers should increase usable intensity by suppressing LPI. concomitant in ablation pressure would allow implosion low-aspect-ratio pellets to ignition substantial gain (&gt;20) at much reduced energy. proposed KrF-laser-based Fusion...
We have built a high-DC-voltage photoemission gun and diagnostic beamline permitting us to measure rms transverse emittance (/spl epsi//spl tilde//sub x/) momentum spread delta/) of short-duration electron pulses produced by illuminating the cathode with light from mode-locked, frequency-doubled Nd:YLF laser. The is GaAs photocathode source designed operate at 500 kV. measured /spl x/ delta/ for conditions ranging emittance-dominated space-charge-dominated. report these measurements as...
The longitudinal drift expansion and compression of a space-charge dominated electron beam with parabolic line charge profile has been studied experimentally to verify the validity envelope equation. experimental configuration measurement results are reported. Good agreement is found between theoretical predictions from calculations results.
A detailed understanding of the physics space-charge dominated beams is vital for many advanced accelerators that desire to achieve high beam intensity. In regard, low-energy, high-intensity electron provide an excellent model system. The University Maryland Electron ring (UMER), currently under construction, has been designed study with extreme intensity in a strong focusing lattice dispersion. tune shift UMER will be more than order magnitude greater exiting synchrotrons and rings. 10-keV,...
Jefferson Lab is developing a 10 MeV injector to provide an electron beam for high-power free-electron laser (FEL). To characterize the transverse phase space of space-charged-dominated produced by this injector, we designed interceptive multislit emittance diagnostic. It incorporates algorithm phase-space reconstruction and subsequent calculation Twiss parameters both directions at update rate exceeding 1 Hz, speed that will facilitate transverse-phase-space matching between FEL's...
Laser plasma instabilities are problematic for inertial confinement fusion because they can spoil illumination uniformity, reduce laser-target coupling, and create unwanted fast electrons. Recent experiments simulations have shown that self-seeded stimulated rotational Raman scattering (SRRS) in air might achieve enough spectral broadening to mitigate these with only moderate of the focal spot. The theoretical model included chaotic broadband spatially multimode light, but was a scalar...
The 10 keV, 100 mA, Pierce-type electron gun and injector for the University of Maryland Electron Ring (UMER) Project are described. Using a pulsed control grid located 0.15 mm from 4-mm radius cathode, 100-ns bunches generated. A/K gap is variable, producing beam currents ranging 50 to 160 mA. A rotatable aperture plate included allow six different masks, including pepperpot. Beam current after measured with built-in Rogowski coil. line consists solenoid lens, five printed-circuit...
Research at the Naval Laboratory pursues advanced laser technologies that can mitigate plasma instabilities (LPI) in applications such as inertial confinement fusion. Increased bandwidth is currently being developed a strategy to suppress LPI. In particular, stimulated rotational Raman scattering (SRRS) has been demonstrated using Nike krypton fluoride (KrF) facility viable method for enhancing bandwidth. The technique applicable other large facilities. Through combination of high-intensity...
Experimental and numerical studies of emittance growth resulting from beam mismatch have been performed at the University Maryland Electron Beam Transport Experiment. A 5‐beamlet distribution energy 5 keV total current 44 mA passes through two‐solenoid matching lenses into a 36‐solenoid transport channel. Theory predicts substantial due to density nonuniformity, mismatch, misalignment. Experimentally, configuration is mismatched transported Random misalignments in channel produce gradually...
In this paper the current plans for diagnostic complement Jefferson Lab's IRFEL are presented. Diagnostic devices include optical transition radiation beam viewers, both stripline and button position monitors, multislit emittance measuring devices, coherent synchrotron bunch length monitoring light cameras profile at high average power. Most have update rates of order 1 sec or shorter, all controlled through an EPICS control system.
Numerical and experimental studies of emittance growth halo formation arising from beam mismatch have been performed. A mismatched 5 keV, 44 mA electron distribution passes through a 36-solenoid transport channel. Past verified the agreement between experiment, simulation, theory. simulation results show that is responsible for mismatch. Now used to find correlation initial halo.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Experimental studies of emittance growth resulting from beam mismatch have been performed. A five-beamlet distribution 44 mA and 5 kV passes through two solenoid matching lenses into a 36-solenoid transport channel. Theory predicts substantial due to mismatch. The configuration is mismatched, the final measured. Experiment simulation results suggest that large halo source predicted growth.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>