Jonathan Wurtele - Academia.edu (original) (raw)

Papers by Jonathan Wurtele

Muon Colliders have unique technical and physics advantages and disadvantages when compared with ... more Muon Colliders have unique technical and physics advantages and disadvantages when compared with both hadron and electron machines. They should thus be regarded as complementary. Parameters are given of 4 TeV and 0.5 TeV high luminosity µ + µ − colliders, and of a 0.5 TeV lower luminosity demonstration machine. We discuss the various systems in such muon colliders, starting from the proton accelerator needed to generate the muons and proceeding through muon cooling, acceleration and storage in a collider ring. Problems of detector background are also discussed.

Physical Review Special Topics - Accelerators and Beams, 1999

We introduce a specific class of BGK-type waves that arise naturally in slowly-evolving Vlasov pl... more We introduce a specific class of BGK-type waves that arise naturally in slowly-evolving Vlasov plasmas, characterized by a distribution function in terms of the canonical particle action. Using some naturally motivated assumptions and the constraints of self-consistency, we determine the wave's nonlinear properties and compare these to driven Vlasov systems. We then show how this may lead to reduced models

Achieving the maximum possible current density continues to be an important goal with far ranging... more Achieving the maximum possible current density continues to be an important goal with far ranging applications. The space charge limit to current in diodes can be affected by a number of parameters, such as finite emitter size [1] and short pulse length [2]. Here, using a particle-in-cell code, we examine a number of interesting phenomena associated with space charge limited

We numerically model the Princeton experiments on Raman amplification [1] using averaged-PIC (aPI... more We numerically model the Princeton experiments on Raman amplification [1] using averaged-PIC (aPIC) [2] and 3-wave codes. Recently, there has been a series of experimental results performed in Princeton University [3]. Amplification factors up to 500 in intensity were obtained using a subpicosecond pulse propagating in a 3mm plasma. The plasma was created using a gas jet. The intensity of

Abstract: This report constitutes the third deliverable of LBNL s contracted role in the FERMI@ E... more Abstract: This report constitutes the third deliverable of LBNL s contracted role in the FERMI@ Elettra Technical Optimization study. It describes proposed R&D activities for the baseline design of the Technical Optimization Study, initial studies of the RF gun mode-...

We report on design studies for a seeded FEL light source that is responsive to the scientific ne... more We report on design studies for a seeded FEL light source that is responsive to the scientific needs of the future. The FEL process increases radiation flux by several orders of magnitude above existing incoherent sources, and offers the additional enhancements attainable by optical manipulations of the electron beam: control of the temporal duration and bandwidth of the coherent output, reduced gain length in the FEL, utilization of harmonics to attain shorter wavelengths, and precise synchronization of the x-ray pulse with seed laser systems. We describe an FEL facility concept based on a high repetition rate RF photocathode gun, that would allow simultaneous operation of multiple independent FEL's, each producing high average brightness, tunable over the VUV-soft x-ray range, and each with individual performance characteristics determined by the configuration of the FEL. SASE, enhanced-SASE (ESASE), seeded, harmonic generation, and other configurations making use of optical manipulations of the electron beam may be employed, providing a wide range of photon beam properties to meet varied user demands.

Physical Review Special Topics - Accelerators and Beams, 2003

We describe the status of our effort to realize a first neutrino factory and the progress made in... more We describe the status of our effort to realize a first neutrino factory and the progress made in understanding the problems associated with the collection and cooling of muons towards that end.

Proceedings Particle Accelerator Conference, 1995

The proposal to perform a series of plasma lens experiments at the Final Focus Test Beam at SLAC ... more The proposal to perform a series of plasma lens experiments at the Final Focus Test Beam at SLAC has been described earlier. We report on our progress towards validation of concepts involved in the experiments, including the laser ionized plasma production test, development of the supersonic gas jet as the plasma source, and study on focused beam size measurement techniques. Most importantly, the effects of background events due to plasma lenses in future linear collider detectors, such as that in the NLC, are studied in details and are shown to be within detector tolerances.

Proceedings of International Conference on Particle Accelerators, 1993

We intend to carry out a series of plasma lens experiments at the Final Focus Test Beam facility ... more We intend to carry out a series of plasma lens experiments at the Final Focus Test Beam facility at SLAC. These experiments will be the first to study the focusing of particle beams by plasma focusing &vices in the parameter regime of interest for high energy colliders, and is expected to lead to plasma lens designs capable of unprecedented spot sizes. Plasma focusing of positron beams will be attempted for the first time. We will study the effects of lens aberrations due to various lens imperfections. Several approaches will be applied to create the plasma required including laser ionization and beam ionization of a working gas. At an increased bunch population of 2.5x lOlo, tunneling ionization of a gas target by an electron beam -an effect which has never been observed before -should be significant. The compactness of our device should prove to be of interest for applications at the SLC and the next generation linear colliders.

We outline in detail a staging scenario for realizing the Neutrino Factory and the Muon Collider.... more We outline in detail a staging scenario for realizing the Neutrino Factory and the Muon Collider. As a first stage we envisage building an intense proton source that can be used to perform high intensity conventional neutrino beam experiments ("Superbeams"). While this is in progress, we perform R&D in collecting, cooling and accelerating muons which leads to the next two

LUX is a design study to develop concepts for future ul- trafast x-ray facilities. Presently, LUX... more LUX is a design study to develop concepts for future ul- trafast x-ray facilities. Presently, LUX is based on an elec- tron beam accelerated to ∼3-GeV energy in a supercon- ducting, recirculating linac. Included in the design are mul- tiple free-electron laser (FEL) beamlines which use the har- monic cascade approach to produce coherent XUV & soft X-ray emission beginning with a strong input seed at ∼200- nm wavelength obtained from a "conventional" laser. Each cascade module generally operates in the low-gain regime and is composed of a radiator together with a modulator section, separated by a magnetic chicane. The chicane temporally delays the electron beam pulse in order that a "virgin" pulse region (with undegraded energy spread) be brought into synchronism with the radiation pulse. For a given cascade, the output photon energy can be selected over a wide range by varying the seed laser wavelength and the field strength in the undulators. We present numerica...

Within the framework of Hilbert space theory, we have developed a maximum-power variational princ... more Within the framework of Hilbert space theory, we have developed a maximum-power variational principle applicable to classical spontaneous radiation from prescribed classical harmonic current sources. A simple proof is summarized for the case of three-dimensional fields propagating in vacuum, and specialization to the case of paraxial optics is discussed. The techniques have been developed to model undulator radiation from relativistic electron beams (for which an example involving high harmonic generation is reviewed), but are more broadly applicable to synchrotron or other radiation problems, and may generalize to certain structured media.

Physics of Plasmas, 2004

A numerical code based on an eikonal formalism has been developed to simulate laser-plasma intera... more A numerical code based on an eikonal formalism has been developed to simulate laser-plasma interactions, specifically Raman backscatter (RBS). In this code, the dominant laser modes are described by their wave envelopes, avoiding the need to resolve the laser frequency; appropriately time-averaged equations describe particle motion. The code is fully kinetic, and thus includes critical physics such as particle trapping and Landau damping which are beyond the scope of the commonly used fluid three-wave equations. The dominant forces on the particles are included: the ponderomotive force resulting from the beat wave of the forward and backscattered laser fields and the self-consistent plasma electric field. The code agrees well, in the appropriate regimes, with the results from three-wave equations and particle-in-cell simulations. The effects of plasma temperature on RBS amplification are studied. It is found that increasing the plasma temperature results in modification to particle trapping and the saturation of RBS, even before the onset of Landau damping of the plasma wave. This results in a reduction in the coupling efficiency compared to predictions based on the three-wave equations.

Physics of Plasmas, 1998

... inferred an ion acoustic speed of We find that the average ionization degree is about 3, resu... more ... inferred an ion acoustic speed of We find that the average ionization degree is about 3, resulting in a plasma temperature of about 65 eV. The expansion is found to evolve as as expected from theory. From the discussion in Sec. IV B, such a channel is capable of guiding a laser ...

Physics of Plasmas, 2009

Progress on developing a plasma amplifier/compressor based on stimulated Raman scattering of nano... more Progress on developing a plasma amplifier/compressor based on stimulated Raman scattering of nanosecond laser pulses is reported. Generation of a millijoule seed pulse at a wavelength that is redshifted relative to the pump beam has been achieved using an external Raman gas cell. By interacting the shifted picosecond seed pulse and the nanosecond pump pulse in a gas jet plasma at a density of ϳ10 19 cm −3 , the upper limit of the pump intensity to avoid angular spray of the amplified seed has been determined. The Raman amplification has been studied as a function of the pump and seed intensities. Although the heating of plasma by the nanosecond pump pulse results in strong Landau damping of the plasma wave, an amplified pulse with an energy of up to 14 mJ has been demonstrated, which is, to the best of our knowledge, the highest output energy so far by Raman amplification in a plasma. One-dimensional particle-in-cell simulations indicate that the saturation of amplification is consistent with onset of particle trapping, which might be overcome by employing a shorter seed pulse.

Physical Review Letters, 2004

A modified version of the Plasma Beat-Wave Accelerator scheme is introduced and analyzed, which i... more A modified version of the Plasma Beat-Wave Accelerator scheme is introduced and analyzed, which is based on autoresonant phase-locking of the nonlinear Langmuir wave to the slowly chirped beat frequency of the driving lasers via adiabatic passage through resonance. This new scheme is designed to overcome some of the well-known limitations of previous approaches, namely relativistic detuning and nonlinear modulation or other non-uniformity or non-stationarity in the driven Langmuir wave amplitude, and sensitivity to frequency mismatch due to measurement uncertainties and density fluctuations and inhomogeneities. As in previous schemes, modulational instabilities of the ionic background ultimately limit the useful interaction time, but nevertheless peak electric fields at or approaching the wave-breaking limit seem readily attainable. Compared to traditional approaches, the autoresonant scheme achieves larger accelerating electric fields for given laser intensity, or comparable fields for less laser power; the plasma wave excitation is much more robust to variations or uncertainties in plasma density; it is largely insensitive to the precise choice of chirp rate, provided only that chirping is sufficiently slow; and the quality and uniformity of the resulting plasma wave and its suitability for accelerator applications may be superior. In underdense plasmas, the total frequency shift required is only of the order of a few percent of the laser carrier frequency, and for possible experimental proofs-of-principle, the scheme might be implemented with relatively little additional modification to existing systems based on either solid-state amplifiers and Chirped Pulse Amplification techniques, or, with somewhat greater technological effort, using a CO2 or other gas laser system.

Nuclear Physics B - Proceedings Supplements, 1996

The status is presented of the laser wakefield acceleration research at the l'OASIS laborato... more The status is presented of the laser wakefield acceleration research at the l'OASIS laboratory of the Center for Beam Physics at LBNL. Experiments have been performed on laser driven production of relativistic electron beams from plasmas using a high repetition rate (10 Hz), high power (10 TW) Ti:sapphire (0.8 mum) laser system. Large amplitude plasma waves have been excited in the self-modulated laser wakefield regime by tightly focusing (spot diameter 8 mum) a single high power (=50 fs) laser pulse onto a high density (>1019 cm-3) pulsed gasjet (length 1.2 mm). Nuclear activation measurements in lead and copper targets indicate the production of electrons with energy in excess of 25 MeV. This result was confirmed by electron distribution measurements using a bending magnet spectrometer. Progress on implementing the colliding pulse laser injection method is also presented. This method is expected to produce low emittance (<1pi mm-mrad), low energy spread (<1%), ultras...

Journal of Plasma Physics, 2011

Abstract Experiments demonstrate the~ 77× amplification of 0.5 to 3.5-ps pulses of seed light by ... more Abstract Experiments demonstrate the~ 77× amplification of 0.5 to 3.5-ps pulses of seed light by interaction with Langmuir waves in a low density (1.2× 10 19 cm− 3) plasma produced by a 1-ns, 230-J, 1054-nm pump beam with 1.2× 10 14 W/cm 2 intensity. The waves are ...