Plasma density temporal evolution in a high-power microwave pulse compressor switch

Beilin, Leonid; Shlapakovski, A.; Donskoy, Moshe; Queller, T.; Krasik, Ya. E.

doi:10.1209/0295-5075/109/25001

Cited by 9 publications

(16 citation statements)

References 8 publications

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“…1. The microwave compressor, same as in [6] and [7], was assembled using standard WR284-waveguide-based parts: the cavity waveguide with the input iris was connected at the output end to the H -plane tee with shorted side arm. The cavity gain of the compressor was ∼17 dB at an operating frequency 2766.9 MHz.…”

Section: Experimental Setup and Resultsmentioning

confidence: 99%

“…The compressor was charged by 2-μs pulses produced by a Communications & Power Industries VMS1177 magnetron. As in [7], the system was filled with helium at an absolute pressure of 2 · 10 5 Pa. The setup for timeresolved spectroscopy was described in detail in [7].…”

Section: Experimental Setup and Resultsmentioning

confidence: 99%

“…As in [7], the system was filled with helium at an absolute pressure of 2 · 10 5 Pa. The setup for timeresolved spectroscopy was described in detail in [7]. The light emitted from the plasma discharge was focused by a lens onto the entrance slit of the Spex 750M spectrometer.…”

Section: Experimental Setup and Resultsmentioning

confidence: 99%

“…4(a)], optical emission starts actually after the compressor output pulse reaches maximal power, while for the case when the beam is perpendicular to the field, significant light emission is observed even before output pulse extraction. The temporal evolution of the plasma density derived from the line-shape analysis evaluating the Stark broadening of the obtained spectral lines (as described in [7]) for the pulses yielding similar microwave output powers for different laser beam directions does not differ significantly in the density rise time and maximal value. There is, however, the difference in the time when a dense (>10 14 cm −3 ) plasma appears with respect to the moment that the laser beam enters the system, as shown in Fig.…”

Section: Experimental Setup and Resultsmentioning

confidence: 99%

“…In addition, the influence of laser beam intensity is studied. The experiments were conducted as a continuation of the investigations [7], in which time-resolved optical emission spectroscopy was used to evaluate the nanosecond-scale dynamics of the plasma density. Therefore, helium was employed as the gas filling the system since helium is appropriate for spectroscopic measurements.…”

Section: Introductionmentioning

confidence: 99%

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Operation of a Microwave Pulse Compressor With a Laser-Triggered Plasma Switch at Different Laser Beam Directions

Shlapakovski

Beilin

Hadas

et al. 2015

IEEE Trans. Plasma Sci.

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A resonant microwave pulse compressor with laser triggering of the plasma discharge in its switch was studied for the influence of the unfocused laser beam direction with respect to the RF electric field. The compressor was realized as a rectangular waveguide-based cavity connected to an H-plane waveguide tee with a shorted side arm filled with pressurized helium and pumped by a conventional pulsed S-band magnetron. It was found that neither the direction, nor the intensity of the laser beam significantly affect the compressor output pulse peak power and waveform. Meantime, the delay between the moment of plasma discharge initiation and the appearance of the microwave output is shorter and the time jitter for this delay is smaller if the laser beam is directed along the RF electric field. The same effect was observed when increasing the intensity of the laser beam. Time-resolved optical emission spectroscopy was used to evaluate the plasma density, and numerical simulations of the RF energy release from the system with the appearance of plasma showed a good agreement with the experimentally obtained characteristics of the plasma and microwave output pulse. Index Terms-Laser triggering, microwave pulse compression, plasma switch. Leonid Beilin received the B.Sc., M.Sc., and Ph.D. degrees in physics from the Technion-Israel Institute of Technology (Technion), Haifa, Israel, in 2006, 2010, and 2015, respectively. His Ph.D. research focused on nanosecond timescale plasma formation in the presence of highintensity electromagnetic field with the Plasma and

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Section: Experimental Setup and Resultsmentioning

confidence: 99%

Section: Experimental Setup and Resultsmentioning

confidence: 99%

Section: Experimental Setup and Resultsmentioning

confidence: 99%

Section: Experimental Setup and Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Operation of a Microwave Pulse Compressor With a Laser-Triggered Plasma Switch at Different Laser Beam Directions

Shlapakovski

Beilin

Hadas

et al. 2015

IEEE Trans. Plasma Sci.

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Self-induced gaseous plasma as high power microwave opening switch medium

et al. 2015

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Self-induced gaseous plasma is evaluated as active opening switch medium for pulsed high power microwave radiation. The self-induced plasma switch is investigated for N2 and Ar environments under pressure conditions ranging from 25 to 700 Torr. A multi-pass TE111 resonator is used to significantly reduce the delay time inherently associated with plasma generation. The plasma forms under the pulsed excitation of a 4 MW magnetron inside the central dielectric tube of the resonator, which isolates the inner atmospheric gas from the outer vacuum environment. The path from the power source to the load is designed such that the pulse passes through the plasma twice with a 35 ns delay between these two passes. In the first pass, initial plasma density is generated, while the second affects the transition to a highly reflective state with as much as 30 dB attenuation. Experimental data revealed that virtually zero delay time may be achieved for N2 at 25 Torr. A two-dimensional fluid model was developed to study the plasma formation times for comparison with experimental data. The delay time predicted from this model agrees well with the experimental values in the lower pressure regime (error < 25%), however, due to filamentary plasma formation at higher pressures, simulated delay times may be underestimated by as much as 50%.

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Self-consistent evolution of plasma discharge and electromagnetic fields in a microwave pulse compressor

et al. 2015

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Nanosecond-scale evolution of plasma and RF electromagnetic fields during the release of energy from a microwave pulse compressor with a plasma interference switch was investigated numerically using the code MAGIC. The plasma was simulated in the scope of the gas conductivity model in MAGIC. The compressor embodied an S-band cavity and H-plane waveguide tee with a shorted side arm filled with pressurized gas. In a simplified approach, the gas discharge was initiated by setting an external ionization rate in a layer crossing the side arm waveguide in the location of the electric field antinode. It was found that with increasing ionization rate, the microwave energy absorbed by the plasma in the first few nanoseconds increases, but the absorption for the whole duration of energy release, on the contrary, decreases. In a hybrid approach modeling laser ignition of the discharge, seed electrons were set around the electric field antinode. In this case, the plasma extends along the field forming a filament and the plasma density increases up to the level at which the electric field within the plasma decreases due to the skin effect. Then, the avalanche rate decreases but the density still rises until the microwave energy release begins and the electric field becomes insufficient to support the avalanche process. The extraction of the microwave pulse limits its own power by terminating the rise of the plasma density and filament length. For efficient extraction, a sufficiently long filament of dense plasma must have sufficient time to be formed. V

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Plasma density temporal evolution in a high-power microwave pulse compressor switch

Cited by 9 publications

References 8 publications

Operation of a Microwave Pulse Compressor With a Laser-Triggered Plasma Switch at Different Laser Beam Directions

Operation of a Microwave Pulse Compressor With a Laser-Triggered Plasma Switch at Different Laser Beam Directions

Self-induced gaseous plasma as high power microwave opening switch medium

Self-consistent evolution of plasma discharge and electromagnetic fields in a microwave pulse compressor

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