Neutral gas heating via non-resonant optical lattices

Cornella, Barry; Gimelshein, S. F.; Lilly, Taylor; Ketsdever, Andrew D.

doi:10.1063/1.4829918

Cited by 6 publications

(10 citation statements)

References 27 publications

(29 reference statements)

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“…It should be noted that a similar chirped laser system has been successfully used in the chirped lattice gas acceleration studies of Maher-McWilliams et al [30]. These laser parameters were chosen to be in a regime below the optical breakdown threshold [17,31,32], and excepting gas-dependent pulse duration and the temporal flattop profile of the pulse, correspond to similar experimental conditions to those found in [5,20,26,33]. While the laser upon which these simulations are based specifies chirp excursions in excess of 10 GHz/µs, the maximum chirp rates and frequency shift limits for single-mode behavior are largely dictated by the design and cavity size of the master microchip and amplifier lasers.…”

Section: Methodsmentioning

confidence: 97%

“…demonstrated high fidelity in modeling the impact of non-resonant laser interference patterns on gases [5,20,[24][25][26]. Modified to include the non-resonant, optical lattice gas interaction described above, the code approximates the force on a particle by a temporally and spatially varying acceleration, which was considered constant over the duration of a simulation time step.…”

Section: Methodsmentioning

confidence: 99%

“…Since then, optical lattices have become a powerful instrument in the study of rarefied gas dynamics, with applications ranging from micropropulsion [3], gas heating and cooling [4][5][6], to gas phase diagnostics [7][8][9]. Previous numerical studies of optical lattice-induced gas heating have predicted temperature changes on the order of several thousand Kelvin using the technique [10][11][12],…”

Section: Introductionmentioning

confidence: 99%

“…While these numerical studies have predicted several fold increases in available gas temperature changes [12,13,15], the use of multipass cavities places significant experimental constraints on efforts to achieve maximum energy deposition, with optical energy losses, damage thresholds, alignment challenges, and fixed optical lattice velocities further limiting gas heating potential. Incorporating the recent development of a chirped laser for optical Stark deceleration [16], this study employs the direct simulation Monte Carlo code SMILE in an effort to provide insight into how optical lattice laser pulse parameters affect heating magnitudes attainable through optical lattice gas heating [5]. Using pulse intensities that avoid ionization of the gas [17], this work specifically looks at intrapulse frequency chirping, first proposed by Barker et al [2], as a way to continually update lattice velocities to better reflect that required by the instantaneous state of the gas for optimal energy deposition.…”

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confidence: 99%

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Optical lattice gas heating simulation under application of intrapulse frequency chirping

2015

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but these studies have largely failed to account for realistic, experimental considerations by using pulse energies and durations that would lead to ionization of the gas (optical breakdown) or, as a result of the Fourier transform limit, would make achieving the narrowband, monochromatic nature of the interaction required for optimal heating difficult. Given these realistic experimental limitations, combined with low intrinsic energy deposition efficiency (10 −5 ), such ~2000 K temperatures changes are not likely to be realized using a traditional monochromatic singleshot implementation [12]. In an effort to sidestep this intrinsic energy deposition inefficiency, some groups have looked at heating in the context of multipass, non-resonant, optical cavities [13,14]. In these cavity configurations, a laser pulse that remains largely unaffected in the single-pass case is given increased opportunity for energy deposition, and thus higher final temperatures, over the single-pass case. While these numerical studies have predicted several fold increases in available gas temperature changes [12,13,15], the use of multipass cavities places significant experimental constraints on efforts to achieve maximum energy deposition, with optical energy losses, damage thresholds, alignment challenges, and fixed optical lattice velocities further limiting gas heating potential. Incorporating the recent development of a chirped laser for optical Stark deceleration [16], this study employs the direct simulation Monte Carlo code SMILE in an effort to provide insight into how optical lattice laser pulse parameters affect heating magnitudes attainable through optical lattice gas heating [5]. Using pulse intensities that avoid ionization of the gas [17], this work specifically looks at intrapulse frequency chirping, first proposed by Barker et al. [2], as a way to continually update lattice velocities to better reflect that required by the instantaneous state of the gas for optimal energy deposition.Abstract Direct simulation Monte Carlo was used to investigate the interaction between molecular nitrogen, argon, and methane, initially at 300 K and 0.8 atm, and frequency-chirped, pulsed optical lattices. The simulated optical lattice parameters are consistent with published optical lattice-based experiments to ensure that pulse energies and durations do not exceed optical breakdown (ionization) thresholds. In an effort to maximize optical lattice gas heating, laser pulses were chirped to produce lattice velocities which more effectively facilitate energy deposition throughout the pulse duration. The maximum end pulse translational temperature obtained in nitrogen, argon, and methane was 763, 715, and 1018 K, respectively.

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Section: Methodsmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Optical lattice gas heating simulation under application of intrapulse frequency chirping

2015

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“…As a result, optical lattices have become a powerful instrument in the study of rarified gas dynamics, with applications ranging from micropropulsion, gas heating and cooling, to gas phase diagnostics [3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Kinetic view of chirped optical lattice gas heating

Graul¹,

Gimelshein²,

Lilly³

2014

AIP Conference Proceedings

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With a focus on optical lattice gas heating, direct simulation Monte Carlo was used to investigate the interaction between molecular nitrogen, argon and methane, initially at 300 K and 0.8 atm, with pulsed, chirped optical lattices. Created from two 700 mJ, 532 nm, flattop laser pulses, the optical lattice parameters simulated are based on published optical lattice-based experiments, to ensure that pulse energies and durations do not exceed published optical breakdown (ionization) thresholds. Resultant translational gas temperatures, as well as induced bulk velocities, were used quantify energy and momentum deposition. To maximize available gas temperature changes achieved using the technique, laser pulses were linearly chirped to produce lattice velocities able to more effectively facilitate energy deposition throughout the pulse duration. From the initial conditions, the maximum, end pulse axial translational temperature obtained in nitrogen was approximately 755 K, at a lattice velocity of 400 m/s linearly chirped at 25 Gm/s 2 over the 40 ns pulse duration. To date, this stands as the single largest, numerically-predicted temperature change from optical lattice gas heating under the numerical integration of real world energy and laser-based limitations.

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