Reflection and refraction of electromagnetic waves by a moving ionization region

Sorokin, Yu. M.; Stepanov, N. S.

doi:10.1007/bf01033011

Cited by 3 publications

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“…Conversion of static electric fields by their interaction with moving ionization fronts has attracted considerable attention due to the possibilities of its use for the creation of frequency-tunable sources of electromagnetic radiation [1][2][3][4][5][6][7][8][9][10][11][12]. In the context of such a conversion, one-dimensional Doppler-like effects are often considered when waves interact with a transversely unlimited ionization front [1][2][3][4][5][6][7][13][14][15][16][17][18][19][20][21][22][23]. A spatially periodic electric field produced by a system of capacitors is usually considered a wave to be converted.…”

Section: Introductionmentioning

confidence: 99%

Dc to ac field conversion due to leaky-wave excitation in a plasma slab behind an ionization front

Kostin

Vvedenskii

2015

New J. Phys.

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We present a way for generating coherent tunable electromagnetic radiation through dc to ac field conversion by an ionization front. The conversion is caused by the excitation of leaky waves behind the transversely limited ionization front propagating in a uniform electrostatic field. This differs significantly from the well-known dc-to-ac-radiation-converter models which consider Doppler-like frequency conversion by a transversely unlimited ionization front propagating in a spatially periodic electric field. We explore the dispersion properties and excitation of these leaky waves radiated through the transverse plasma boundary at the Cherenkov angle to the direction of propagation of a superluminal ionization front as dependent on the parameters of the plasma produced and on the speed of the ionization front. It is shown that not only the center frequency but also the duration and waveform of the generated pulse may significantly depend on the speed of the ionization front. The results indicate the possibility of using such converters based on planar photoconductive antennas to create sources of microwave and terahertz radiation with controllable waveforms that are transformed from video to radio pulse when the angle of incident ionizing radiation is tuned. laser pulse on a photoconductive material flat boundary [5,6,20,21]. In this case, the speed of the generated ionization front is greater than the speed of light and is determined by the incident angle of the ionizing radiation, which makes it easy to control the front speed through the adjustment of the angle. Available femtosecond laser systems are capable of securing the propagation of such fronts over sufficiently long distances and the formation of subsurface plasma over sufficiently large areas (tens of square centimeters) [24][25][26][27]. Photoconductive devices (including large-area ones) that use ultrafast ionization have been used for generation, detection, frequency conversion, phase shifting, and fast switching of terahertz or microwave radiation (see, e.g., [5][6][7][20][21][22][23][24][25][26][27][28][29][30][31]).Since the speed of propagation of ionization fronts is greater than the speed of light, fast leaky polarization waves are excited behind the front and radiate energy through the transverse plasma boundaries at an angle to the direction of front propagation. Leaky waves have been actively studied for more than half a century (see, e.g., [32][33][34][35][36][37][38][39][40][41][42][43]) and are now attracting attention in the context of the development of emitting and receiving devices with large apertures, including those which use metamaterials and photonic crystals [39][40][41][42][43]. In our case, the excited leaky waves are of a rarely studied type; they have complex values of frequency and wavenumber whose ratio has a real value equal to the speed of the ionization front. Here lies a distinction between our problem and similar ones regarding the conversion of plane waves interacting with an instantly generated plasma slab or half...

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Section: Introductionmentioning

confidence: 99%

Dc to ac field conversion due to leaky-wave excitation in a plasma slab behind an ionization front

Kostin

Vvedenskii

2015

New J. Phys.

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“…It was noted more than 20 years ago [3][4][5][6] that reflection can occur not only from a moving plasma but also from a moving over-dense plasma boundary, such as an ionization or recombination front. Lampe et al [6] studied the interaction of an em wave with an over-dense ionization front moving with superluminous speed.…”

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confidence: 99%

“…Instead, the interaction results in two "transmitted" waves that, in the laboratory frame, are moving in the direction of the front. Sorokin and Stepanov [3] found that an ionization front, moving with a uniform velocity U in a dielectric with permittivity´, behaves as a drifting plasma layer with equivalent dielectric constant given by´͑ v͒ ´͕1 2 ͓v 2 e ͞v͑v 2 ig͔͒ ͑1 2 b͒ ͑1 1 b͒ 21 ͖ .…”

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confidence: 99%

“…The amplitude of the reflected waves can be found for an arbitrary profile of the front using the formal technique of the "auxiliary reflection front" first presented by Stepanov [3]. For a sharp, step function front, it suffices to apply the boundary conditions on the discontinuity surface; these conditions require that the tangential parts of E and B are continuous [6] across the front.…”

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confidence: 99%

“…A peculiarity in this case is that the total energy in the secondary waves is smaller than that of the primary wave. This is a well-known effect [3][4][5][6] and it can be attributed to the excitation of a zero frequency pure "magnetic wave" in the plasma with wave number k 0 . The magnetic wave is formed because, when the electrons are suddenly created, they are accelerated by the electric field of the em wave with a phase such as to create the static magnetic field.…”

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confidence: 99%

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Conversion of Electrostatic to Electromagnetic Waves by Superluminous Ionization Fronts

2001

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The conversion of static electric fields to electromagnetic radiation by the incidence of a superluminous ionization front on plasma is investigated. For extremely superluminous fronts, the radiation is close to the plasma frequency and is converted with efficiency of order unity. A proof-of-principle experiment was conducted using semiconductor plasma containing an alternately charged capacitor array. The process has important implications in astrophysical plasmas, such as supernova emission, and to laboratory development of compact, coherent, tunable radiation sources in the THz range.

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Cascaded chirped photon acceleration for efficient frequency conversion

Edwards

Jia

et al. 2018

Physics of Plasmas

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A cascaded sequence of photon acceleration stages using the instantaneous creation of a plasma density gradient by flash ionization allows the generation of coherent and chirped ultraviolet and x-ray pulses with independently tunable frequency and bandwidth. The efficiency of the cascaded process scales with 1/ω in energy, and multiple stages produce significant frequency up-conversion with gas-density plasmas. Chirping permits subsequent pulse compression to few-cycle durations, and output frequencies are not limited to integer harmonics.

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Reflection and refraction of electromagnetic waves by a moving ionization region

Cited by 3 publications

References 0 publications

Dc to ac field conversion due to leaky-wave excitation in a plasma slab behind an ionization front

Dc to ac field conversion due to leaky-wave excitation in a plasma slab behind an ionization front

Conversion of Electrostatic to Electromagnetic Waves by Superluminous Ionization Fronts

Cascaded chirped photon acceleration for efficient frequency conversion

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