1,775 research outputs found
An analytical and experimental investigation of resistojet plumes
As a part of the electrothermal propulsion plume research program at the NASA Lewis Research Center, efforts have been initiated to analytically and experimentally investigate the plumes of resistojet thrusters. The method of G.A. Simons for the prediction of rocket exhaust plumes is developed for the resistojet. Modifications are made to the source flow equations to account for the increased effects of the relatively large nozzle boundary layer. Additionally, preliminary mass flux measurements of a laboratory resistojet using CO2 propellant at 298 K have been obtained with a cryogenically cooled quartz crystal microbalance (QCM). There is qualitative agreement between analysis and experiment, at least in terms of the overall number density shape functions in the forward flux region
Generation of sub-picosecond electron bunches from RF photoinjectors
Abstract In this paper we discuss the possibility to generate sub-picosecond electron bunches directly from a photoinjector by illuminating a photo-cathode in an RF cavity with a phase-locked sub-picosecond laser pulse. In particular, we address all de-bunching effects taking place during acceleration and transport through a photoinjector. We provide analysis of the beam dynamics, as well as the comparison with numerical simulations. The possible performances of the present SATURNUS linac setup are presented, as well as the anticipated capabilities of a multi-cell RF gun structure based on the PWT linac presently in operation at UCLA
Electron beam transfer line design for plasma driven Free Electron Lasers
Plasma driven particle accelerators represent the future of compact
accelerating machines and Free Electron Lasers are going to benefit from these
new technologies. One of the main issue of this new approach to FEL machines is
the design of the transfer line needed to match of the electron-beam with the
magnetic undulators. Despite the reduction of the chromaticity of plasma beams
is one of the main goals, the target of this line is to be effective even in
cases of beams with a considerable value of chromaticity. The method here
explained is based on the code GIOTTO [1] that works using a homemade genetic
algorithm and that is capable of finding optimal matching line layouts directly
using a full 3D tracking code.Comment: 9 Pages, 4 Figures. A related poster was presented at EAAC 201
Measuring Gaussian quantum information and correlations using the Renyi entropy of order 2
We demonstrate that the Renyi-2 entropy provides a natural measure of
information for any multimode Gaussian state of quantum harmonic systems,
operationally linked to the phase-space Shannon sampling entropy of the Wigner
distribution of the state. We prove that, in the Gaussian scenario, such an
entropy satisfies the strong subadditivity inequality, a key requirement for
quantum information theory. This allows us to define and analyze measures of
Gaussian entanglement and more general quantum correlations based on such an
entropy, which are shown to satisfy relevant properties such as monogamy.Comment: 6+5 pages, published in PRL. Typo in Eq. (1) correcte
Optical implementation and entanglement distribution in Gaussian valence bond states
We study Gaussian valence bond states of continuous variable systems,
obtained as the outputs of projection operations from an ancillary space of M
infinitely entangled bonds connecting neighboring sites, applied at each of
sites of an harmonic chain. The entanglement distribution in Gaussian valence
bond states can be controlled by varying the input amount of entanglement
engineered in a (2M+1)-mode Gaussian state known as the building block, which
is isomorphic to the projector applied at a given site. We show how this
mechanism can be interpreted in terms of multiple entanglement swapping from
the chain of ancillary bonds, through the building blocks. We provide optical
schemes to produce bisymmetric three-mode Gaussian building blocks (which
correspond to a single bond, M=1), and study the entanglement structure in the
output Gaussian valence bond states. The usefulness of such states for quantum
communication protocols with continuous variables, like telecloning and
teleportation networks, is finally discussed.Comment: 15 pages, 6 figures. To appear in Optics and Spectroscopy, special
issue for ICQO'2006 (Minsk). This preprint contains extra material with
respect to the journal versio
Plasma boosted electron beams for driving Free Electron Lasers
In this paper, we report results of simulations, in the framework of both
EuPRAXIA \cite{Walk2017} and EuPRAXIA@SPARC\_LAB \cite{Ferr2017} projects,
aimed at delivering a high brightness electron bunch for driving a Free
Electron Laser (FEL) by employing a plasma post acceleration scheme. The
boosting plasma wave is driven by a tens of \SI{}{\tera\watt} class laser and
doubles the energy of an externally injected beam up to \GeV{1}. The injected
bunch is simulated starting from a photoinjector, matched to plasma, boosted
and finally matched to an undulator, where its ability to produce FEL radiation
is verified to yield O(\num{e11}) photons per shot at \nm{2.7}.Comment: 5 pages, 2 figure
Quantum SASE FEL with a laser wiggler
Quantum effects in high-gain FELs are ruled by the quantum FEL parameter, \u3c1 = pmcy/hkr, which is the ratio between the momentum spread at saturation and the one photon momentum recoil. It has been shown that when 3c\u3c1 64 1 the spectrum of the emitted radiation changes from the broad continuous and chaotic spectrum of the classical regime to a series of discrete and equally spaced very narrow lines, due to transitions between discrete momentum states. In this paper we show that the quantum regime can be achieved using Kilometers long magnetic wigglers or a laser wiggler. In this paper we state the scaling laws necessary to operate a Quantum SASE FEL in the Angstrom region with a laser wiggler. Specific example is given having in mind a high power Ti: Sa laser wiggler at \u3bb= 0.8 \u3bcm, in construction at LNF-INFN Laboratories, for the SPARC/PLASMON-X project
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