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Plasma and Beam Physics

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Full-Text Articles in Physics

Beam-Energy And Centrality Dependence Of Direct-Photon Emission From Ultra-Relativistic Heavy-Ion Collisions, A. Adare, Nicole J. Apadula, Sergey Belikov, Paul Constantin, Lei Ding, Alan Dion, Nathan C. Grau, John C. Hill, Nels J. Hotvedt, Todd Kempel, John G. Lajoie, Alexandre Lebedev, S. H. Lee, Craig Ogilvie, Milap R. Patel, H. Pei, Jan Rak, Timothy T. Rinn, Marzia Rosati, Jonathan C. Runchey, Alexey Yu. Semenov, Abhisek Sen, M. Shimomura, C. L. Silva, S. Skutnik, Carla Vale, Feng Wei, Et Al. Jul 2019

Beam-Energy And Centrality Dependence Of Direct-Photon Emission From Ultra-Relativistic Heavy-Ion Collisions, A. Adare, Nicole J. Apadula, Sergey Belikov, Paul Constantin, Lei Ding, Alan Dion, Nathan C. Grau, John C. Hill, Nels J. Hotvedt, Todd Kempel, John G. Lajoie, Alexandre Lebedev, S. H. Lee, Craig Ogilvie, Milap R. Patel, H. Pei, Jan Rak, Timothy T. Rinn, Marzia Rosati, Jonathan C. Runchey, Alexey Yu. Semenov, Abhisek Sen, M. Shimomura, C. L. Silva, S. Skutnik, Carla Vale, Feng Wei, Et Al.

Craig Ogilvie

The PHENIX collaboration presents first measurements of low-momentum (0.41\,GeV/c) direct-photon yield dNdirγ/dη is a smooth function of dNch/dη and can be well described as proportional to (dNch/dη)α with α≈1.25. This scaling behavior holds for a wide range of beam energies at the Relativistic Heavy Ion Collider and the Large Hadron Collider, for centrality selected samples, as well as for different, A+A collision systems. At a given beam energy the scaling also holds for high pT (>5\,GeV/c) but when results from different collision energies are compared, an additional sNN ...


Equation Of State Of Boron Nitride Combining Computation, Modeling, And Experiment, Shuai Zhang, Amy Lazicki, Burkhard Militzer, Lin H. Yang, Kyle Caspersen, Jim A. Gaffney, Markus W. Däne, John E. Pask, Walter R. Johnson, Abhiraj Sharma, Phanish Suryanarayana, Duane D. Johnson, Andrey V. Smirnov, Philip A. Sterne, David Erskine, Richard A. London, Federica Coppari, Damian Swift, Joseph Nilsen, Art J. Nelson, Heather D. Whitley Jun 2019

Equation Of State Of Boron Nitride Combining Computation, Modeling, And Experiment, Shuai Zhang, Amy Lazicki, Burkhard Militzer, Lin H. Yang, Kyle Caspersen, Jim A. Gaffney, Markus W. Däne, John E. Pask, Walter R. Johnson, Abhiraj Sharma, Phanish Suryanarayana, Duane D. Johnson, Andrey V. Smirnov, Philip A. Sterne, David Erskine, Richard A. London, Federica Coppari, Damian Swift, Joseph Nilsen, Art J. Nelson, Heather D. Whitley

Duane D. Johnson

The equation of state (EOS) of materials at warm dense conditions poses significant challenges to both theory and experiment. We report a combined computational, modeling, and experimental investigation leveraging new theoretical and experimental capabilities to investigate warm-dense boron nitride (BN). The simulation methodologies include path integral Monte Carlo (PIMC), several density functional theory (DFT) molecular dynamics methods [plane-wave pseudopotential, Fermi operator expansion (FOE), and spectral quadrature (SQ)], activity expansion (actex), and all-electron Green's function Korringa-Kohn-Rostoker (mecca), and compute the pressure and internal energy of BN over a broad range of densities and temperatures. Our experiments were conducted at the ...


Generation Of Broadband Thz Pulses By Laser Wakefield At Radial Boundary Of Plasma Column, Serge Y. Kalmykov, Alexander Englesbe, Jennifer Elle, Andreas Schmitt-Sody Mar 2019

Generation Of Broadband Thz Pulses By Laser Wakefield At Radial Boundary Of Plasma Column, Serge Y. Kalmykov, Alexander Englesbe, Jennifer Elle, Andreas Schmitt-Sody

Serge Youri Kalmykov

Photoionization of an ambient gas by a tightly focused, femtosecond, weakly relativistic laser pulse leaves behind
the pulse a column of electron density (a “filament”). At the column surface, the density drops to zero within a thin (micronscale) boundary layer. Ponderomotive force of the pulse drives within the filament a cylindrical wave of charge separation (laser wake). If the pulse waist size is much smaller than the Langmuir wavelength, electron current in the wake is mostly transverse. In the filament surface area, this current rapidly decays (electrons, crossing the sharp density gradient, phase out of wake within a few Langmuir ...


Gas Pressure Dependence Of Microwave Pulses Generated By Laser-Produced Filament Plasmas, Alexander Englesbe, Jennifer Elle, Remington Reid, Adrian Lucero, Hugh Pohle, Matthew Domonkos, Serge Y. Kalmykov, Karl Krushelnick, Andreas Schmitt-Sody Oct 2018

Gas Pressure Dependence Of Microwave Pulses Generated By Laser-Produced Filament Plasmas, Alexander Englesbe, Jennifer Elle, Remington Reid, Adrian Lucero, Hugh Pohle, Matthew Domonkos, Serge Y. Kalmykov, Karl Krushelnick, Andreas Schmitt-Sody

Serge Youri Kalmykov

The plasma arising due to the propagation of a filamenting ultrafast laser pulse in air contains currents driven by the pulse that generate radiated electromagnetic fields. We report absolutely calibrated measurements of the frequency spectrum of microwaves radiated by the filament plasma from 2–40 GHz. The emission pattern of the electric field spectrum is mapped as a function of air pressure from atmosphere to 0.5 Torr. For fixed laser pulse energy, duration, and focal geometry, we observe that decreasing the air pressure by a factor of approximately 103 increases the amplitude of the electric field waveform by a ...


Optically Controlled Laser-Plasma Electron Acceleration For Compact Gamma-Ray Sources, Serge Y. Kalmykov, X. Davoine, Isaac Ghebregziabher, Bradley A. Shadwick Feb 2018

Optically Controlled Laser-Plasma Electron Acceleration For Compact Gamma-Ray Sources, Serge Y. Kalmykov, X. Davoine, Isaac Ghebregziabher, Bradley A. Shadwick

Serge Youri Kalmykov

Thomson scattering (TS) from electron beams produced in laser-plasma accelerators may generate femtosecond pulses of quasi-monochromatic, multi-MeV photons. Scaling laws suggest that reaching the necessary GeVelectron energy, with a percent-scale energy spread and five-dimensional brightness over 10^16 A/m^2, requires acceleration in centimeter-length, tenuous plasmas (n ~ 10^17 cm^-#3;3), with petawatt-class lasers. Ultrahigh per-pulse power mandates single-shot operation, frustrating applications dependent on dosage. To generate high-quality near-GeV beams at a manageable average power (thus affording kHz repetition rate), we propose acceleration in a cavity of electron density, driven with an incoherent stack of sub-Joule laser pulses ...


Optically Controlled Laser-Plasma Electron Accelerator For Compact Gamma-Ray Sources, Serge Y. Kalmykov, X. Davoine, Isaac Ghebregziabher, Bradley A. Shadwick Feb 2018

Optically Controlled Laser-Plasma Electron Accelerator For Compact Gamma-Ray Sources, Serge Y. Kalmykov, X. Davoine, Isaac Ghebregziabher, Bradley A. Shadwick

Serge Youri Kalmykov

Generating quasi-monochromatic, femtosecond gamma-ray pulses via Thomson scattering (TS) demands exceptional electron beam (e-beam) quality, such as percent scale energy spread and five-dimensional brightness over 10^16 A/m^2. We show that near-GeV e-beams with these metrics can be accelerated in a cavity of electron density, driven with an incoherent stack of Joule-scale laser pulses through a mm-size, dense plasma (n ~ 10^19 cm^-􀀀3). Changing the time delay, frequency difference, and energy ratio of the stack components controls the e-beam phase space on the femtosecond scale, while the modest energy of the optical driver helps afford kHz-scale repetition ...


Multi-Color, Femtosecond Gamma-Ray Pulse Trains Driven By Comb-Like Electron Beams, Serge Y. Kalmykov, X. Davoine, Isaac Ghebregziabher, Bradley A. Shadwick Feb 2018

Multi-Color, Femtosecond Gamma-Ray Pulse Trains Driven By Comb-Like Electron Beams, Serge Y. Kalmykov, X. Davoine, Isaac Ghebregziabher, Bradley A. Shadwick

Serge Youri Kalmykov

Photon engineering can be exploited to control the nonlinear evolution of the drive pulse in a laser–plasma accelerator (LPA), offering new avenues to tailor electron beam phase space on a femtosecond time scale. One promising option is to drive an LPA with an incoherent stack of two sub-Joule, multi-TW pulses of different colors. Slow self-compression of the bi-color optical driver delays electron dephasing, boosting electron beam energy without accumulation of a massive low-energy tail. The modest energy of the stack affords kHz-scale repetition rate at manageable laser average power. Propagating the stack in a pre-formed plasma channel induces periodic ...


Velocity–Space Drag And Diffusion In A Model, Two-Dimensional Plasma, Mark Anthony Reynolds, B.D. Fried, G.J. Morales Mar 2017

Velocity–Space Drag And Diffusion In A Model, Two-Dimensional Plasma, Mark Anthony Reynolds, B.D. Fried, G.J. Morales

M. Anthony Reynolds

The quasilinear fluctuation integral is calculated for a two-dimensional, unmagnetized plasma ~composed of charged rods!, and is expressed in terms of Fokker–Planck coefficients. It is found that in two dimensions, the enhanced fluctuations generated by fast electrons lead to anomalously large transport coefficients. In particular, the effect of a small population of fast electrons is only weakly dependent on their density. In three dimensions, the effect of fast electrons is masked by the dominant approximation, but higher-order terms describe processes similar to those in two dimensions, and these terms can become significant for weakly stable plasmas. The differences between ...


Ion Bernstein Waves Driven By Two Transverse Flow Layers, Mark Anthony Reynolds, G. Ganguli Mar 2017

Ion Bernstein Waves Driven By Two Transverse Flow Layers, Mark Anthony Reynolds, G. Ganguli

M. Anthony Reynolds

The interaction between two narrow layers of E3B flow is investigated, along with their stability properties. The mode frequencies, growth rates, and eigenfunctions are calculated. It is found that the instability due to a single layer is robust to the inclusion of a second layer. Specifically, when the separation between the layers is on the order of the ion-cyclotron radius, there is strong coupling between the two layers and the second layer is destabilizing. In addition, when the flow velocities are in opposite directions a wide variety of modes is possible, including near-zero-frequency modes, resulting in broadband structure in both ...


High-Frequency Fluctuations Of A Modulated, Helical Electron Beam, Mark Anthony Reynolds Mar 2017

High-Frequency Fluctuations Of A Modulated, Helical Electron Beam, Mark Anthony Reynolds

M. Anthony Reynolds

The high-frequency electromagnetic field generated by a density-modulated, helical electron beam propagating in a magnetized plasma is calculated. The magnetic fluctuations are found to exhibit spatially localized ~evanescent! resonances at harmonics of the electron-cyclotron frequency, whose width is determined by the pitch angle of the beam, and whose existence is a consequence of the helical geometry. In addition, electrostatic modes are radiated near the hybrid frequencies, and electromagnetic modes are radiated above the upper-hybrid frequency. The predicted frequency spectrum and mode structure in configuration space are in good agreement with experimental observations of discrete emission lines at the electron-cyclotron harmonics.


Multi-Color Γ-Rays From Comb-Like Electron Beams Driven By Incoherent Stacks Of Laser Pulses, Serge Y. Kalmykov, X. Davoine, Isaac Ghebregziabher, Bradley A. Shadwick Mar 2017

Multi-Color Γ-Rays From Comb-Like Electron Beams Driven By Incoherent Stacks Of Laser Pulses, Serge Y. Kalmykov, X. Davoine, Isaac Ghebregziabher, Bradley A. Shadwick

Serge Youri Kalmykov

Trains of fs-length, GeV-scale electron bunches with controlled energy spacing and a 5-D brightness up to
10^17 A/m^2 may be produced in a mm-scale uniform plasma. The main element of the scheme is an incoherent stack of 10-TW-scale laser pulses of different colors, with mismatched focal spots, with the highest-frequency pulse advanced in time. While driving an electron density bubble, this stack remains almost proof against nonlinear red-shift and self-compression. As a consequence, the unwanted continuous injection of background electrons is minimized. Weak focusing of the trailing (lower-frequency) component of the stack enforces expansions and contractions of ...


Femtosecond Pulse Trains Of Polychromatic Inverse Compton Γ-Rays From Designer Electron Beams Produced By Laser-Plasma Acceleration In Plasma Channels, Serge Y. Kalmykov, Isaac Ghebregziabher, X. Davoine, Remi Lehe, Agustin F. Lifschitz, Victor Malka, Bradley A. Shadwick Oct 2016

Femtosecond Pulse Trains Of Polychromatic Inverse Compton Γ-Rays From Designer Electron Beams Produced By Laser-Plasma Acceleration In Plasma Channels, Serge Y. Kalmykov, Isaac Ghebregziabher, X. Davoine, Remi Lehe, Agustin F. Lifschitz, Victor Malka, Bradley A. Shadwick

Serge Youri Kalmykov

Propagating a short, relativistically intense laser pulse in a plasma channel makes it possible to generate clean comb-like electron beams – sequences of synchronized, low phase-space volume bunches with controllable energy spacing [S. Y. Kalmykov et al., “Accordion Effect Revisited: Generation of Comb-Like Electron Beams in Plasma Channels,” in Advanced Accelerator Concepts: 16th Workshop, AIP Conference Proceedings; this volume]. All-optical control of the electron beam phase space structure via manipulation of the drive pulse phase (negative chirp) and parameters of the channel enables the design of a tunable, all-optical source of polychromatic pulsed gamma-rays using the mechanism of inverse Compton scattering.


Accordion Effect Revisited: Generation Of Comb-Like Electron Beams In Plasma Channels, Serge Y. Kalmykov, X. Davoine, Remi Lehe, Agustin F. Lifschitz, Bradley A. Shadwick Oct 2016

Accordion Effect Revisited: Generation Of Comb-Like Electron Beams In Plasma Channels, Serge Y. Kalmykov, X. Davoine, Remi Lehe, Agustin F. Lifschitz, Bradley A. Shadwick

Serge Youri Kalmykov

Propagating a short, relativistically intense laser pulse in a plasma channel makes it possible to generate comb-like electron beams – sequences of synchronized, low phase-space volume bunches with controllable energy difference. The tail of the pulse, confined in the accelerator cavity (electron density “bubble”), transversely flaps, as the pulse head steadily self-guides. The resulting oscillations of the cavity size cause periodic injection of electrons from ambient plasma, creating an energy comb with the number of components, their energy, and energy separation dependent on the channel radius and pulse length. Accumulation of noise (continuously injected charge) can be prevented using a negatively ...


Electron Acceleration And Generation Of High-Brilliance X-Ray Radiation In Kilojoule, Subpicosecond Laser-Plasma Interactions, Serge Y. Kalmykov, X. Davoine Oct 2016

Electron Acceleration And Generation Of High-Brilliance X-Ray Radiation In Kilojoule, Subpicosecond Laser-Plasma Interactions, Serge Y. Kalmykov, X. Davoine

Serge Youri Kalmykov

Petawatt, picosecond laser pulses offer rich opportunities in generating synchrotron x-rays. This paper concentrates on the regimes accessible with the PETAL laser, which is a part of the Laser Megajoule (LMJ) facility. We explore two physically distinct scenarios through Particle-in-Cell simulations. The first one realizes in a dense plasma, such that the period of electron Langmuir oscillations is much shorter than the pulse duration. Hallmarks of this regime are longitudinal breakup (“self-modulation”) of the picosecond-scale laser pulse and excitation of a rapidly evolving broken plasma wake. It is found that electron beams with a charge of several tens of nCcan ...


High-Flux Femtosecond X-Ray Emission From Controlled Generation Of Annular Electron Beams In A Laser Wakefield Accelerator, T. Z. Zhao, K. Behm, C. F. Dong, X. Davoine, Serge Y. Kalmykov, V. Petrov, Vladimir Chvykov, P. Cummings, B. Hou, Anatoly Maksimchuk, J. A. Nees, Victor Yanovsky, A. G. R. Thomas, Karl Krushelnick Aug 2016

High-Flux Femtosecond X-Ray Emission From Controlled Generation Of Annular Electron Beams In A Laser Wakefield Accelerator, T. Z. Zhao, K. Behm, C. F. Dong, X. Davoine, Serge Y. Kalmykov, V. Petrov, Vladimir Chvykov, P. Cummings, B. Hou, Anatoly Maksimchuk, J. A. Nees, Victor Yanovsky, A. G. R. Thomas, Karl Krushelnick

Serge Youri Kalmykov

Annular quasimonoenergetic electron beams with a mean energy in the range 200–400 MeV and charge on the order of several picocoulombs were generated in a laser wakefield accelerator and subsequently accelerated using a plasma afterburner in a two-stage gas cell. Generation of these beams is associated with injection occurring on the density down ramp between the stages. This well-localized injection produces a bunch of electrons performing coherent betatron oscillations in the wakefield, resulting in a significant increase in the x-ray yield. Annular electron distributions are detected in 40% of shots under optimal conditions. Simultaneous control of the pulse duration ...


Coherent Beam Combining Of Ultrashort Laser Pulses.Pdf, Ahmad Azim Apr 2016

Coherent Beam Combining Of Ultrashort Laser Pulses.Pdf, Ahmad Azim

Ahmad Azim

In this thesis, CBC of ultrashort laser pulses is investigated based upon the method known as divided-pulse amplification (DPA). Active, passive and hybrid DPA have been achieved in a flashlamp-pumped Nd:YAG laser seeded from a Ti:sapphire mode-locked laser. Picosecond pulses at a repetition rate of 2.5 Hz were amplified and combined to record energy of 216 mJ with a combination efficiency of 80%. Engineering of the Nd:YAG amplifier chain for high-efficiency energy extraction is presented. In addition, phasing of actively divided pulses with a CW pilot laser co-propagating with the pulsed beam is also demonstrated. Analysis ...


Controlled Generation Of Comb-Like Electron Beams In Plasma Channels For Polychromatic Inverse Thomson Gamma-Ray Sources, Serge Y. Kalmykov, X. Davoine, I Ghebregziabher, R Lehe, A F. Lifschitz, B A. Shadwick Feb 2016

Controlled Generation Of Comb-Like Electron Beams In Plasma Channels For Polychromatic Inverse Thomson Gamma-Ray Sources, Serge Y. Kalmykov, X. Davoine, I Ghebregziabher, R Lehe, A F. Lifschitz, B A. Shadwick

Serge Youri Kalmykov

Propagating a relativistically intense, negatively chirped laser pulse (the bandwidth > 150 nm) in a plasma channel makes it possible to generate background-free, comb-like electron beams - sequences of synchronized bunches with a low phase-space volume and controlled energy spacing. The tail of the pulse, confined in the accelerator cavity (an electron density ‘bubble’), experiences periodic focusing, while the head, which is the most intense portion of the pulse, steadily self-guides. Oscillations of the cavity size cause periodic injection of electrons from the ambient plasma, creating an electron energy comb with the number of components, their mean energy, and energy spacing dependent ...


Customizable Electron Beams From Optically Controlled Laser Plasma Acceleration For Γ-Ray Sources Based On Inverse Thomson Scattering, Serge Y. Kalmykov, X. Davoine, Isaac Ghebregziabher, Bradley A. Shadwick Jan 2016

Customizable Electron Beams From Optically Controlled Laser Plasma Acceleration For Γ-Ray Sources Based On Inverse Thomson Scattering, Serge Y. Kalmykov, X. Davoine, Isaac Ghebregziabher, Bradley A. Shadwick

Serge Youri Kalmykov

Laser wakefield acceleration of electrons in the blowout regime can be controlled by tailoring the laser pulse phase and the plasma target. The100nm-scale bandwidth and negative frequency chirp of the optical driver compensate for the nonlinear frequency red-shift imparted by wakefield excitation.This mitigates pulse self-steepening and suppresses continuous injection. The plasma channel suppresses diffraction of the pulse leading edge, further reducing self-steepening, making injection even quieter. Besides, the channel destabilizes the pulse tail confined within the accelerator cavity (the electron density “bubble”), causing oscillations in the bubble size. The resulting periodic injection generates background-free comb-like beams – sequences of synchronized ...


Abrupt Change In Neon Discharge Plasma Detected Through Optogalvanic Effects, Xianming Han, Michael Blosser, Prabhakar Misra, Haridass Chandran Oct 2015

Abrupt Change In Neon Discharge Plasma Detected Through Optogalvanic Effects, Xianming Han, Michael Blosser, Prabhakar Misra, Haridass Chandran

Xianming Han

When a laser is tuned between two excited energy levels of a gas in a Direct Current discharge lamp, the discharge current will experience a temporary disturbance lasting tens or hundreds of microseconds known as the optogalvanic effect. We have carried out extensive studies of optogalvanic effects in neon discharge plasmas for transitions at 621.7 nm, 630.5 nm, 638.3 nm, 650.7 nm and 659.9 nm. A nonlinear least-squares Monte Carlo technique has been used to determine the relevant amplitude coefficients, decay rates and the instrumental time constant. We discovered an abrupt change in the neon ...


Collisional Ionization Of Excited State Neon In A Gas Discharge Plasma, Xianming Han, Verl Wiseheart, Scott Conner, Meng-Chih Su, David Monts Oct 2015

Collisional Ionization Of Excited State Neon In A Gas Discharge Plasma, Xianming Han, Verl Wiseheart, Scott Conner, Meng-Chih Su, David Monts

Xianming Han

We report the first case where it is possible to clearly identify and quantitatively characterize the dominant physical processes contributing to production of the optogalvanic effect (OGE) signal in a discharge plasma. This work concentrates on the simplest case where only two states are involved in the optical transition. The theoretical model with only four parameters is in excellent agreement with the experimentally obtained time-resolved OGE waveforms. The collisional ionization rate in the upper state is twice as fast as that in the lower state although the two states are only separated by 1.94 eV. We conclude that the ...


Laser-Wakefield Accelerators: Glass-Guiding Benefits, Donald P. Umstadter Jul 2015

Laser-Wakefield Accelerators: Glass-Guiding Benefits, Donald P. Umstadter

Donald P. Umstadter

A main attraction of laser-driven electron accelerators is their absence of cavity walls, which can break down in the presence of intense electric fields. Now it seems that the inclusion of a hollow glass fibre cavity could lead to more efficient acceleration at lower laser intensities. ... Further research will reveal which of the above methods for guiding light will ultimately prove best for future accelerator designs. In any case, although it is perhaps ironic that the relatively old technology of glass waveguides may benefit next-generation accelerators, it is nonetheless satisfying to see such a classic photonic solution come to the ...


Optical Control Of Electron Phase Space In Plasma Accelerators With Incoherently Stacked Laser Pulses, Serge Y. Kalmykov, Xavier Davoine, Remi Lehe, Agustin F. Lifschitz, Bradley A. Shadwick May 2015

Optical Control Of Electron Phase Space In Plasma Accelerators With Incoherently Stacked Laser Pulses, Serge Y. Kalmykov, Xavier Davoine, Remi Lehe, Agustin F. Lifschitz, Bradley A. Shadwick

Serge Youri Kalmykov

It is demonstrated that synthesizing an ultrahigh-bandwidth, negatively chirped laser pulse by incoherently stacking pulses of different wavelengths makes it possible to optimize the process of electron self-injection in a dense, highly dispersive plasma (n_0 \sim 10^{19} cm^{-3}). Avoiding transformation of the driving pulse into a relativistic optical shock maintains a quasi-monoenergetic electron spectrum through electron dephasing and boosts electron energy far beyond the limits suggested by existing scaling laws. In addition, evolution of the accelerating bucket in a plasma channel is shown to produce a background-free, tunable train of femtosecond-duration, 35 - 100 kA, time-synchronized quasi-monoenergetic electron bunches ...


Influence Of Admixture Gas On The Enhancement Of Neutron Production In Plasma Focus Devices, Ahmad Talaei, S.M. Kaia Oct 2014

Influence Of Admixture Gas On The Enhancement Of Neutron Production In Plasma Focus Devices, Ahmad Talaei, S.M. Kaia

Ahmad Talaei

In this article, considering the most important interactions between the ionized admixture particles and the working plasma ones, we have analyzed the effect of added gas on the current and confinement time of the pinched plasma in plasma focus devices. Moreover, we demonstrate how heating and cooling the pinched plasma can be controlled by the increase and decrease on the percentage of the added particles and by this way the rise in the rate of D–D nuclear reactions is calculated.


Study The Output Characteristics Of A 90 Kj Filippove-Type Plasma Focus, S.M. Kiai, Ahmad Talaei, Et Al. Oct 2014

Study The Output Characteristics Of A 90 Kj Filippove-Type Plasma Focus, S.M. Kiai, Ahmad Talaei, Et Al.

Ahmad Talaei

The output characteristics of a Filippove-Type plasma focus “Dena” (288 μF, 25 kV, 90 kJ) is numerically investigated by considering the voltage, current, current derivative, and maximum current as a function of capacitor bank energy in the constant Argon gas pressure and compared to the experiment. It is shown that increase on the bank energy leads to the increment on the maximum current and decrement on the pinch time.


Effects Of Admixture Gas On The Production Of 18f Radioisotope In Plasma Focus Devices, Ahmad Talaei, S.M. Kaia, A. Zeem Oct 2014

Effects Of Admixture Gas On The Production Of 18f Radioisotope In Plasma Focus Devices, Ahmad Talaei, S.M. Kaia, A. Zeem

Ahmad Talaei

In this article, the effect of admixture gas on the heating and cooling of pinched plasma directly related to the enhancement or reduction of 18F production through the 16O(3He, p)18F is considered in the plasma focus devices. It is shown that by controlling the velocity of added Oxygen particles mixed with the working helium gas into the plasma focus chamber, one can increase the current and decrease the confinement time (plasma heating) or vice verse (plasma cooling). The highest level of nuclear activities of 18F was found around 16% of the Oxygen admixture ...


Pinched Plasma Study In A Filippov-Type Plasma Focus “Dena”, Ahmad Talaei, S. Kaia, S. Adlparvar Oct 2014

Pinched Plasma Study In A Filippov-Type Plasma Focus “Dena”, Ahmad Talaei, S. Kaia, S. Adlparvar

Ahmad Talaei

A characteristic feature of physical processes occurring in pinched plasma is their tendency to generate thermal and nonthermal emissions. In this case, the roles played by plasma compression dynamics such as pinch formation, pinch disruption, expansion, etc., are predominant. In this paper, first, we present some of the experimental results concerning the thermal and nonthermal neutron emissions. Then, a new approach based on some theoretical assumptions and the experimental data for which the pinched plasma density evolution was studied are introduced. In the new approach, the compression dynamics are divided into two phases: plasma compression (thermal) and plasma expansion (nonthermal ...


Accordion Effect In Plasma Channels: Generation Of Tunable Comb-Like Electron Beams, Serge Y. Kalmykov, Bradley A. Shadwick, Isaac A. Ghebregziabher, Xavier Davoine, Remi Lehe, Agustin F. Lifschitz, Victor Malka May 2014

Accordion Effect In Plasma Channels: Generation Of Tunable Comb-Like Electron Beams, Serge Y. Kalmykov, Bradley A. Shadwick, Isaac A. Ghebregziabher, Xavier Davoine, Remi Lehe, Agustin F. Lifschitz, Victor Malka

Serge Youri Kalmykov

Propagating a short, relativistically intense laser pulse in a plasma channel makes it possible to generate comb-like electron beams for advanced radiation sources. The ponderomotive force of the leading edge of the pulse expels all electrons facing the pulse. The bare ions attract the ambient plasma electrons, forming a closed bubble of electron density confining the pulse tail. The cavity of electron density evolves slowly, in lock-step with the optical driver, and readily traps background electrons. The combination of a bubble (a self-consistently maintained, “soft” hollow channel) and a preformed channel forces transverse flapping of the laser pulse tail, causing ...


Physical Processes At Work In Sub-30fs, Pw Laser Pulse-Driven Plasma Accelerators: Towards Gev Electron Acceleration Experiments At Cilex Facility., Arnaud Beck, Serge Y. Kalmykov, Xavier Davoine, Agustin F. Lifschitz, Bradley A. Shadwick, Victor Malka, Arnd E. Specka Feb 2014

Physical Processes At Work In Sub-30fs, Pw Laser Pulse-Driven Plasma Accelerators: Towards Gev Electron Acceleration Experiments At Cilex Facility., Arnaud Beck, Serge Y. Kalmykov, Xavier Davoine, Agustin F. Lifschitz, Bradley A. Shadwick, Victor Malka, Arnd E. Specka

Serge Youri Kalmykov

Optimal regimes and physical processes at work are identified for the first round of laser wakefield acceleration experiments proposed at a future CILEX facility. The Apollon-10P CILEX laser, delivering fully compressed, near-PW-power pulses of sub-25 fs duration, is well suited for driving electron density wakes in the blowout regime in cm-length gas targets. Early destruction of the pulse (partly due to energy depletion)prevents electrons from reaching dephasing, limiting the energy gain to about 3 GeV. However, the optimal operating regimes, found with reduced and full three-dimensional particle-in-cell simulations, show high energy efficiency, with about 10%of incident pulse energy ...


All-Optical Control Of Electron Self-Injection In Millimeter-Scale, Tapered Dense Plasmas., Serge Y. Kalmykov, Xavier Davoine, Bradley A. Shadwick Feb 2014

All-Optical Control Of Electron Self-Injection In Millimeter-Scale, Tapered Dense Plasmas., Serge Y. Kalmykov, Xavier Davoine, Bradley A. Shadwick

Serge Youri Kalmykov

It is demonstrated that a laser pulse with an ultrahigh bandwidth (400 nm) is an asset for future high-repetition-rate , quasimonoenergetic (QME), GeV-scale laser plasma electron accelerators. Manipulating the phase of the driver has a direct impact on evolution of the accelerating bucket (a cavity of electron density maintained by the pressure of the laser pulse radiation), making it possible to control electron self-injection and the final parameters of the QME beam by purely optical means. The large bandwidth makes it possible to compensate for the frequency red-shift accumulated at the pulse leading edge in transit through the plasma. Advancing higher ...


Syllabus_Lecture_Notes_Collective_Phenomena_In_Laser_Plasmas_Ii_Phy998_Spring_2014, Serge Y. Kalmykov Dec 2013

Syllabus_Lecture_Notes_Collective_Phenomena_In_Laser_Plasmas_Ii_Phy998_Spring_2014, Serge Y. Kalmykov

Serge Youri Kalmykov

High-power laser radiation beams interacting with a rarefied, fully ionized plasmas are essentially unstable. This fact is mainly due to the excitation of various modes of plasma oscillations, most important of which are electron Langmuir waves and ion acoustic waves. The stimulated scattering processes destroy and deplete the pulse in the as it propagates. On the other hand, at the moderate level of instability, spectral properties of the scattered light may serve as optical diagnostics of the pulse propagation dynamics. Knowing the dynamics of the stimulated scattering processes is thus essential for such applications as inertial confinement fusion and laser-plasma ...