Laser-induced breakdown in nitrogen and the rare gases at 0.53 and 0.357μm

Rosen, David I.; Weyl, G.

doi:10.1088/0022-3727/20/10/009

Cited by 77 publications

(43 citation statements)

References 27 publications

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“…[23]. It has to be noted that we have obtained lower threshold power densities for N 2 than those given above [21][22][23] ( figure 3). This fact can be related in part to the used focal length (24 cm) and beam size in the focal region (7.85 × 10 −3 cm 2 ) that is one order of magnitude, at least, higher than the values commonly used in the literature, favouring the probability of existence of free electrons to seed the process and decreasing the threshold laser intensity due to the lack of the diffusion losses.…”

Section: Optical Breakdown Threshold Intensities For Nsupporting

confidence: 41%

Optical emission studies of nitrogen plasma generated by IR CO₂laser pulses

Camacho

Poyato

Díaz

et al. 2007

J. Phys. B: At. Mol. Opt. Phys.

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Large-scale plasma produced in nitrogen gas at room temperature and pressures ranging from 4 × 10 3 to 1.2 × 10 5 Pa by high-power laserinduced dielectric breakdown (LIDB) has been investigated. Time-integrated optical nitrogen gas spectra excited from a CO 2 laser have been measured and analysed. The spectrum of the generated plasma is dominated by the emission of strong N + and N and very weak N 2+ atomic lines and molecular features of N (B-X) systems are very weak as compared with the chemiluminescence spectrum of nitrogen formed in a glow discharge. An excitation temperature T exc = 21 000 ± 1300 K was calculated by means of the relative intensity of ionized nitrogen atomic lines assuming local thermodynamic equilibrium. Optical breakdown threshold intensities in N 2 at 9.621 µm have been determined. The physical processes leading to the LIDB of nitrogen in the power density range 0.4 < J < 4.5 GW cm −2 have been analysed. From our experimental observations we can suggest that, although the first electrons must appear via multiphoton ionization or natural ionization, electron cascade is the main mechanism responsible for the LIDB in nitrogen.

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Section: Optical Breakdown Threshold Intensities For Nsupporting

confidence: 41%

Optical emission studies of nitrogen plasma generated by IR CO₂laser pulses

Camacho

Poyato

Díaz

et al. 2007

J. Phys. B: At. Mol. Opt. Phys.

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“…These parameters correspond to an average optical intensity of ~200 GW/cm 2 at the spark location, consistent with published breakdown thresholds in atmospheric pressure air (order ~10 2 -10 3 GW/cm 2 [e.g. [3][4][5][6]). With the 50 cm launch lens we find that the system sparks ~97% of the time.…”

Section: Methodssupporting

confidence: 87%

“…At optical frequencies, both the intensity breakdown and combustion ignition threshold reduce with increasing pressure [e.g. [3][4][5][6]. Thus, we expect the hollow fiber delivery system should readily spark and initiate combustion at the elevated pressures (~20 atm) typical of the targeted engine combustion environments.…”

Section: Resultsmentioning

confidence: 99%

Fundamental Studies of Ignition Processes in Large Natural Gas Engines Using Laser Spark Ignition

Yalin¹,

DeFoort²,

Willson³

2005

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The current report details project progress made during the first quarterly reporting period of the DOE sponsored project "Fundamental studies of ignition processes in large natural gas engines using laser spark ignition". The goal of the overall research effort is to develop a laser ignition system for natural gas engines, with a particular focus on using fiber optic delivery methods. In this report we present our successful demonstration of spark formation using fiber delivery made possible though the use of novel coated hollow fibers. We present results of (high power) experimental characterizations of light propagation using hollow fibers using both a high power research grade laser as well as a more compact laser. Finally, we present initial designs of the system we are developing for future on-engine testing using the hollow fibers.

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“…27 Another way to induce the breakdown is to fix the pressure and to gradually increase the energy until a visible spark is observed around the focal region in a determined number of laser pulses, again 50%. 31 In this last method the obtained threshold value is increased by more than 25% in respect to the previous one. 32 Both methods have been used to measure the trisilane breakdown at different pressures and the results are shown in Fig.…”

Section: Resultsmentioning

confidence: 92%

Laser-induced breakdown spectroscopy of trisilane using infrared CO2 laser pulses

Camacho

Poyato

Díaz

et al. 2007

Journal of Applied Physics

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Synthesis and photoluminescence of fluorinated graphene quantum dots Appl. Phys. Lett. 102, 013111 (2013) The luminescence characteristics of CsI(Na) crystal under α and X/γ excitation J. Appl. Phys. 113, 023101 (2013) Structural and optoelectronic properties of Eu2+-doped nanoscale barium titanates of pseudo-cubic form J. Appl. Phys. 112, 124321 (2012) Quantum yield of luminescence of Ag nanoclusters dispersed within transparent bulk glass vs. glass composition and temperature Appl. Phys. Lett. 101, 251106 (2012) Additional information on J. Appl. Phys. The plasma produced in trisilane ͑Si 3 H 8 ͒ at room temperature and pressures ranging from 50 to 10 3 Pa by laser-induced breakdown ͑LIB͒ has been investigated. The ultraviolet-visible-near infrared emission generated by high-power IR CO 2 laser pulses in Si 3 H 8 has been studied by means of optical emission spectroscopy. Optical breakdown threshold intensities in trisilane at 10.591 m for laser pulse lengths of 100 ns have been measured as a function of gas pressure. The strong emission observed in the plasma region is mainly due to electronic relaxation of excited atomic H and Si and ionic fragments Si + , Si 2+ , and Si 3+ . An excitation temperature T exc = 5600± 300 K was calculated by means of H atomic lines assuming local thermodynamic equilibrium. The physical processes leading to LIB of trisilane in the power density range 0.28 GW cm −2 Ͻ J Ͻ 3.99 GW cm −2 have been analyzed. From our experimental observations we can propose that, although the first electrons must appear via multiphoton ionization, electron cascade is the main mechanism responsible for the breakdown in trisilane.

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Laser-induced breakdown in nitrogen and the rare gases at 0.53 and 0.357μm

Cited by 77 publications

References 27 publications

Optical emission studies of nitrogen plasma generated by IR CO₂laser pulses

Optical emission studies of nitrogen plasma generated by IR CO₂laser pulses

Fundamental Studies of Ignition Processes in Large Natural Gas Engines Using Laser Spark Ignition

Laser-induced breakdown spectroscopy of trisilane using infrared CO2 laser pulses

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Laser-induced breakdown in nitrogen and the rare gases at 0.53 and 0.357μm

Cited by 77 publications

References 27 publications

Optical emission studies of nitrogen plasma generated by IR CO2laser pulses

Optical emission studies of nitrogen plasma generated by IR CO2laser pulses

Fundamental Studies of Ignition Processes in Large Natural Gas Engines Using Laser Spark Ignition

Laser-induced breakdown spectroscopy of trisilane using infrared CO2 laser pulses

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Optical emission studies of nitrogen plasma generated by IR CO₂laser pulses

Optical emission studies of nitrogen plasma generated by IR CO₂laser pulses