Setup involving multi-frame laser probing for studying fast plasma formation with high temporal and spatial resolutions

Parkevich, E. V.; Medvedev, Mikhail; Selyukov, A. S.; Khirianova, A. I.; Mingaleev, A. R.; Mishin, Sergey N.; Pikuz, S. A.; Огинов, А. В.

doi:10.1016/j.optlaseng.2018.12.014

Cited by 19 publications

(12 citation statements)

References 31 publications

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“…The transmitted part of the 0.532 µm radiation is attenuated in the filter by ∼10 4 times. Interferograms were obtained by using the beams reflected from the front and back sides of an air wedge between two rectangular glass prisms of a shearing interferometer [29,30], whereas shadowgrams were registered by using the beam transmitted through the interferometer. The achieved resultant spatial resolution of the imaging system was ∼10 µm for each optical channel.…”

Section: Two-wavelength Laser Probingmentioning

confidence: 99%

Laser scattering by submicron droplets formed during the electrical explosion of thin metal wires

Romanova¹,

Ivanenkov²,

Parkevich³

et al. 2021

J. Phys. D: Appl. Phys.

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This paper presents the results of studying dispersed media formation during the electrical explosion of thin metal wires in vacuum by using low-current generators (∼1–10 kA). Particular attention is paid to the analysis of the composition and structure of the corresponding explosion products as well as to the problem of their visualization using simultaneous laser interferometry and shadow imaging at two wavelengths (1.064 µm and 0.532 µm). Our findings indicate the important role in the visualization of the explosion products that belongs to multiple scattering by submicron droplets of dense condensed matter, which are mixed with metal vapor. The hypothesis on the existence of submicron droplets in the products of exploding metal wires correlates with the results obtained by soft x-ray radiography combined with a laser probing technique. Taking into account the multiple scattering by submicron droplets, it is possible to significantly clarify the parameters of the explosion products visualized via laser probing techniques as well as to gain a deeper insight into the physics behind the electrical wire explosion.

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Section: Two-wavelength Laser Probingmentioning

confidence: 99%

Laser scattering by submicron droplets formed during the electrical explosion of thin metal wires

Romanova¹,

Ivanenkov²,

Parkevich³

et al. 2021

J. Phys. D: Appl. Phys.

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“…The synchronization accuracy between the first probing beam and the high-voltage pulse applied to the gap was better than 1ns. This was achieved by the developed high-voltage cable generator triggered by an ignition laser beam with jitter 1 ns, see more in [35]. To obtain data on the discharge plasma, for each probing beam, we simultaneously employed interferometry, shadow, and schlieren imaging, i.e.…”

Section: Diagnosing Setupmentioning

confidence: 99%

“…The signals from the photodetector, current shunt, and voltage divider were recorded using 1.5GHz digital oscilloscopes(HP Infinium 54845A). The designs of the employed high-voltage generator, three-frame optical system, current and voltage detectors together with the diagnosing methods were described in [35][36][37][38] in detail.…”

Section: Diagnosing Setupmentioning

confidence: 99%

“…The formation of cathode and anode spots is, in fact, an extremely fast phenomenon, and its extensive study is beyond the technical capabilities of the most advanced diagnosing setups [7,35,[39][40][41]. Note that, in our work, the timing accuracy for the instants of the breakdown and the arrival of the first probing beam is ≈0.3 ns with all optical and signal cable delays, as well as the sampling frequency (8 GSa s −1 ) of the oscilloscopes taken into account.…”

Section: Delay Between Instants Of Anode and Cathode Spot Initiationmentioning

confidence: 99%

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Extremely fast formation of anode spots in an atmospheric discharge points to a fundamental ultrafast breakdown mechanism

Parkevich¹,

Medvedev

Khirianova

et al. 2019

Plasma Sources Sci. Technol.

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By employing multi-frame laser interferometry, shadow, and schlieren imaging, we trace the formation of a nanosecond spark discharge in millimeter-sized air gaps formed by a point cathode and flat anode or vice-versa. We discover that the electrical breakdown of the discharge gap is associated with extremely fast (=1 ns) explosive formation of micron-sized cathode and anode spots. We find that the characteristic delay between the instants of the anode and cathode spot initiation can be much shorter than 1ns. The spots appear as highly ionized near-electrode plasmas with an electron density n e ∼10 19 -10 20 cm −3 . The spots then give rise to highly ionized spark channels with pronounced filamentary structures. Our findings indicate that the extremely fast formation of anode spots is associated with an ultrafast gap breakdown promoted by an ultrafast ionization wave (UFIW). The role of the UFIW governed by the rapidly evolving cathode spot is discussed as a fundamental mechanism of the breakdown.

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“…The LTGS output was coupled to a coaxial capacitive voltage divider through a matched transmission line. The divider has a temporal resolution better than 1 ns; its design is described in [22] in detail.…”

Section: Methodsmentioning

confidence: 99%

Laser-triggered gas switch with subnanosecond jitter and breakdown delay tunable over ∼0.1–10 ns governed by the spark gap ignition angle

Parkevich¹,

Medvedev²,

Selyukov³

et al. 2020

Plasma Sources Sci. Technol.

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We created a practical air-lled switch triggered by a ∼ 10 9 W picosecond laser beam with a slightly variable breakdown delay and low jitter. The switch relies on the spark gap with a coaxial geometry, which is ignited by a focused laser beam directed at a certain angle to the gap axis. The switch is integrated with a high-voltage cable generator operating at a constant negative voltage of up to 50 kV. We demonstrate that, by just varying the ignition angle of the spark gap, one can achieve variable breakdown delay tunable within ∼ 0.1-10 ns with 1 ns jitter. Empirical dependences of switching characteristics of the developed device on the ignition angle are obtained. We demonstrate that, combined with variation of the ignition beam energy and charging voltage, variation of the spark gap ignition angle provides superior control over the gap switching characteristics without complicating the switch design. The proposed approach to driving the switching characteristics appears highly promising for designing compact laser-triggered gas switches with variable temporal characteristics and achieving precise synchronization between high-voltage and measuring equipment.

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Setup involving multi-frame laser probing for studying fast plasma formation with high temporal and spatial resolutions

Cited by 19 publications

References 31 publications

Laser scattering by submicron droplets formed during the electrical explosion of thin metal wires

Laser scattering by submicron droplets formed during the electrical explosion of thin metal wires

Extremely fast formation of anode spots in an atmospheric discharge points to a fundamental ultrafast breakdown mechanism

Laser-triggered gas switch with subnanosecond jitter and breakdown delay tunable over ∼0.1–10 ns governed by the spark gap ignition angle

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