Nonlocal-thermal-equilibrium model of a pulsed capillary discharge waveguide

Broks, Bhp Bart; Garloff, K Kurt; Mullen, van der Jjam Joost

doi:10.1103/physreve.71.016401

Cited by 59 publications

(87 citation statements)

References 24 publications

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“…The latter model has been discussed in great detail in Ref. 27. It has been validated by comparison with an experiment, 27 used for parameter studies, 27,31 and a slightly modified version has been used to investigate the effect of modulation of the capillary radius.…”

Section: The Modelmentioning

confidence: 99%

“…27. It has been validated by comparison with an experiment, 27 used for parameter studies, 27,31 and a slightly modified version has been used to investigate the effect of modulation of the capillary radius. 32 We will restrict the discussion of the model used in this work to a summary, emphasizing the difference between the present model and the model used for earlier studies, and refer the interested reader to Ref.…”

Section: The Modelmentioning

confidence: 99%

“…A few types of such waveguides exist, such as dischargeablated waveguides, [15][16][17][18][19][20][21] pinch plasmas, 8,22,23 and slow capillary discharges. 7,[24][25][26][27] Our investigation focuses on the latter. This waveguide has the advantages of long device lifetime and of a long, stable guiding window.…”

Section: Introductionmentioning

confidence: 99%

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Modeling of a square pulsed capillary discharge waveguide for interferometry measurements

et al. 2007

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Slow pulsed capillary discharges in round capillaries are currently under investigation for use as plasma channel laser waveguides in laser-wakefield acceleration, x-ray lasers, and higher-harmonic generation. In this study, a capillary discharge with a square cross section is presented. The electron density, which determines the laser guiding properties, can be measured by means of transverse interferometry in this device. Using a numerical model of the plasma and the capillary wall, an analysis of the discharge is made. The results predict that the square channel is capable of guiding circular laser pulses. The guiding properties are quite similar to those of a round channel with nearly the same diameter as the channel width. This suggests the results obtained by measuring the square capillary discharge are applicable for round channels as well. It was found that the wall heating was inhomogeneous, which makes the wall more susceptible to ablation. The heating of the wall changes the transverse optical pathlength in the interferometry experiments.

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Section: The Modelmentioning

confidence: 99%

Section: The Modelmentioning

confidence: 99%

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Modeling of a square pulsed capillary discharge waveguide for interferometry measurements

et al. 2007

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“…Hydrogen gas, introduced through holes near the capillary ends, was ionized by striking a discharge between electrodes located at each end of the capillary. Measurements [129] and modeling [189,190] showed that a fully ionized, approximately parabolic channel was formed. Hydrogen gas was introduced into the capillary waveguide using two gas slots in the 190 µm and 225 µm diameter capillary and three in the 310 µm capillary.…”

Section: Methodsmentioning

confidence: 99%

Control of Laser Plasma Based Accelerators up to 1 GeV

Nakamura

2007

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This dissertation documents the development of a broadband electron spectrometer (ESM) for GeV class Laser Wakefield Accelerators (LWFA), the production of high quality GeV electron beams (e-beams) for the first time in a LWFA by using a capillary discharge guide (CDG), and a statistical analysis of CDG-LWFAs.An ESM specialized for CDG-LWFAs with an unprecedentedly wide momentum acceptance, from 0.01 to 1.1 GeV in a single shot, has been developed. Simultaneous measurement of e-beam spectra and output laser properties as well as a large angular acceptance (> ±10 mrad) were realized by employing a slitless scheme. A scintillating screen (LANEX Fast back ,LANEX-FB) -camera system allowed faster than 1 Hz operation and evaluation of the spatial properties of e-beams. The design provided sufficient resolution for the whole range of the ESM (below 5% for beams with 2 mrad divergence).The calibration between light yield from LANEX-FB and total charge, and a study on the electron energy dependence (0.071 to 1.23 GeV) of LANEX-FB were performed at the Advanced light source (ALS), Lawrence Berkeley National Laboratory (LBNL). Using this calibration data, the developed ESM provided a charge measurement as well.The production of high quality electron beams up to 1 GeV from a centimeter-scale ii accelerator was demonstrated. The experiment used a 310 µm diameter gas-filled capillary discharge waveguide that channeled relativistically-intense laser pulses (42 TW, A statistical analysis of the CDG-LWFAs' performance was carried out. By taking advantage of the high repetition rate experimental system, several thousands of shots were taken in a broad range of the laser and plasma parameters. An analysis program was developed to sort and select the data by specified parameters, and then to evaluate performance statistically.The analysis suggested that the generation of GeV-level beams comes from a highly unstable and regime. By having the plasma density slightly above the threshold density for self injection, 1) the longest dephasing length possible was provided, which led to the generation of high energy e-beams, and 2) the number of electrons injected into the wakefield was kept small, which led to the generation of high quality (low energy spread) e-beams by minimizing the beam loading effect on the wake. The analysis of the stable half-GeV beam regime showed the requirements for stable self injection and acceleration. A small change of discharge delay t dsc , and input energy E in , significantly affected performance.The statistical analysis provided information for future optimization, and suggested possible schemes for improvment of the stability and higher quality beam generation. A CDG-LWFA is envisioned as a construction block for the next generation accelerator, enabling significant cost and size reductions.

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“…Hydrogen gas, introduced through holes near the capillary ends, was ionized by striking a discharge between electrodes at the capillary ends. Measurements [8] and modelling [10], [11] showed that a fully-ionized, approximately parabolic (with density minimum on axis) plasma channel is formed.…”

Section: Channel-guided Laser Wakefield Acceleratormentioning

confidence: 99%