We present an experimental study of nanosecond high-voltage discharges in a pin-to-pin electrode configuration at atmospheric conditions operating single-pulse mode (no memory effects). Discharge parameters were measured using microwave Rayleigh scattering, laser optical emission spectroscopy enhanced with probing pulse, and fast photography. Spark corona discharge regimes studied for gap sizes 2–10 mm pulse duration 90 ns. The spark regime was observed gaps <6 energies 0.6–1 mJ per...

In this work, a novel diagnostic technique for carbon monoxide (CO) number density measurements in nitrogen buffer mixture at elevated pressures up to 5 bar was developed and tested. The utilizes 2 + 1 resonance enhanced multi-photon ionization (REMPI) of CO induced by femtosecond laser pulse 230.1 nm, followed detection the REMPI-induced electrons using microwave scattering (MS) method (REMPI-MS technique). Dependences REMPI-generated on energy were measured analyzed conjunction with four...

This paper presents the initial development and characterization of a novel micropropulsion system for nanosatellite applications: liquid-fed pulsed plasma thruster (LF-PPT) comprising Lorentz-force accelerator (PPA) low-energy surface flashover (LESF) igniter. In this work, LESF was demonstrated as sufficient means igniting primary discharge in PPA operating with pentaphenyl trimethyl trisiloxane dielectric liquid propellant, propulsion parameters performed. current pulse durations about...

The total number of electrons in a classical microplasma can be non-intrusively measured through elastic in-phase coherent microwave scattering (CMS). Here, we establish theoretical basis for the CMS diagnostic technique with an emphasis on Thomson and collisional short, thin unmagnetized plasma media. Experimental validation is subsequently performed via linearly polarized, variable frequency (10.5-12 GHz) off laser induced 1-760 Torr air-based microplasmas (287.5 nm O2 resonant...

In this work, the temporal decay of electrons produced by an atmospheric pin-to-pin nanosecond discharge operating in spark regime was measured via a combination microwave Rayleigh scattering (MRS) and laser (LRS). Due to initial energy deposition pulse, variation local gas density occurs on timescale electron decay. Thus, assumption constant collisional frequency is no longer applicable when number data are extracted from MRS measurements. To recalibrate measurements throughout period,...

In this work, evolution of parameters nanosecond repetitively pulsed (NRP) discharges in pin-to-pin configuration air was studied during the transient stage initial 20 discharge pulses. Gas and plasma gap were measured using coherent microwave scattering, optical emission spectroscopy, laser Rayleigh scattering for NRP at repetition frequencies 1, 10, 100 kHz. Memory effects (when perturbations induced by previous pulse would not decay fully until subsequent pulse) detected 10 For kHz...

The introduction of mid-IR optical parametric chirped pulse amplifiers has catalyzed interest in multimillijoule, infrared femtosecond pulse-based filamentation. As tunneling ionization is a fundamental first stage these high-intensity laser-matter interactions, characterizing the process critical to understand derivative topical studies on filamentation and self-focusing. Here, we report direct nonintrusive measurements total electron count number densities generated at 3.9...

Nonintrusive measurements of plasma properties are essential to evaluate, and numerically simulate, the in-flight performance electric propulsion systems. As a logical first step in development new diagnostic techniques, this work depicts implementation multiphoton ionization coherent microwave scattering (MPI-CMS) gridded-ion accelerator operating on rare gases. Presented studies primarily comprise photoionization spectroscopy ground excited state-populations both neutrals ions supplemented...

Amorphous calcium carbonate (ACC) is an important precursor for biomineralisation in marine organisms. Among the key outstanding problems regarding ACC are how best to understand its structure and rationalise metastability as amorphous phase. Here, we report high-quality atomistic models of generated by using state-of-the-art interatomic potentials help guide fits X-ray total scattering data. Exploiting a recently-developed inversion approach, extract from these effective...

This paper reports on the use of coherent microwave scattering (CMS) for spatially resolved electron number density measurements elongated plasma structures induced at mid-IR femtosecond filamentation. The presented studies comprise one-dimensional mapping laser filaments via 3.9 um, 127.3 fs pulses output energies up to 15 mJ. axial and intensity were measured be invariant along entire filament length tested pulse 5-15 mJ (2x$10^{15}$ cm$^{-3}$ 30-40 TW/cm$^2$, respectively) which supports...

This paper reports on the use of coherent microwave scattering (CMS) for spatially resolved electron number density measurements elongated plasma structures induced at mid-IR femtosecond filamentation in air. The presented studies comprise one-dimensional mapping laser filaments via 3.9 µm, 127.3 fs pulses output energies up to 15 mJ. axial was measured be invariant (about 2×10^{15}cm^{-3}) along entire filament length and all tested pulse 5-15 mJ, corresponding intensity middle portion...

View Video Presentation: https://doi.org/10.2514/6.2022-1748.vid The total number of electrons in a small plasma object can be non-intrusively measured through elastic in-phase coherent microwave scattering (CMS). In this paper, we develop theoretical foundation for the CMS diagnostic approach fluid-plasma and short dipole formulations – focusing on Thomson collisional regimes elongated microplasmas. We additionally present an experimental validation basis via 11 GHz off laser-induced,...

The characteristics of the plasma plume generated by Low Energy Surface Flashover (LESF) were investigated. triple probe method was used to obtain electron temperature and density, which estimated be 1.44 eV (1~2)×10^13 cm^(-3) at 4 cm from LESF, respectively. In addition, a time-of-flight measurement involving three double probes positioned 3.5 cm, 5 6.5 above LESF assembly suggested propagation speed about 1.5×10^7 cm/s. An angular configuration 40 degrees apart revealed that is primarily...

View Video Presentation: https://doi.org/10.2514/6.2022-2367.vid We present an experimental study of nanosecond high-voltage pulsed discharges in a pin-to-pin configuration at atmospheric conditions operating both single-pulsed mode (no memory effects) and repetitively (with effect). Discharge parameters were measured including voltage, current, gas temperature/density, electron number density. For the mode, two different discharge regimes defined: spark corona. Key parameter controlling...

In this work, coherent microwave scattering in the Thomson regime was demonstrated for small-scale plasmas enclosed within a glass tube and validated using well-known hairpin resonator probe technique. The experiments were conducted DC discharge with diameter of 1.5 cm length 7 cm. (TMS) diagnostics yielded electron number densities about 5.9 × 1010 cm-3, 2.8 1.8 cm-3 air pressures 0.2, 0.5, 2.5 Torr, respectively. Measurements TMS technique consistent across tested frequencies 3-3.9 GHz...

Abstract This paper presents the possibility of using coherent microwave scattering (CMS) for temporally resolved measurements electron momentum-transfer collision frequency in small plasma objects. Specifically, is inferred via phase information from off microplasmas operating mixed collisional-Thomson regime. We further suggest combination and amplitude to derive total counts temperatures plasmas. An experimental validation this concept performed by 10.5 GHz CMS laser-induced,...

View Video Presentation: https://doi.org/10.2514/6.2023-1862.vid This work presents the possibility of temporally-resolved electron momentum-transfer collision frequency measurements in small plasma objects via phase information from coherent microwave scattering (CMS, referring to case constructive elastic scattering). In particular, for plasmas inhabiting mixed collisional-Thomson regime. We additionally recommend combination and amplitude derive total counts temperatures. Finally, by...

Nonintrusive measurements of plasma properties are essential to evaluate, and numerically simulate, the in-flight performance electric propulsion systems. As a logical first step in development new diagnostic techniques, this work depicts implementation multiphoton ionization coherent microwave scattering (MPI-CMS) gridded-ion accelerator operating on rare gases. Presented studies primarily comprise photoionization spectroscopy ground excited state-populations both neutrals ions supplemented...

This paper presents a novel micropropulsion system for nanosatellite applications - liquid fed pulsed-plasma thruster (LF-PPT) comprised of Lorentz-force pulsed plasma accelerator (PPA) and low-energy surface flashover (LESF) igniter. A 3 {\mu}F / 2 kV capacitor bank, offering shot energies < 6 J, supported PPA current durations ~ 16 {\mu}s with observed peaks 7.42 kA. Plasma jet exhaust velocity was measured at 32 km/s using time-of-flight technique via set double probes located along the...

This paper summarizes the design and preliminary characterization of a liquid-fed pulsed-plasma accelerator (LF-PPT) with novel low-energy flashover igniter. A dielectric fluid was utilized as propellant – pentaphenyl trimethyl trisiloxane (C33H34O2Si3). 3μF / 2kV capacitor bank, offering shot energies < 6 J, supported current pulse durations ~ 16μs observed peaks 7.42 kA. Time flight measurements were conducted using biased double probe assembly, suggesting an exhaust velocity ~32 km/s....

This paper presents a non-intrusive diagnostic for gaseous mixtures at elevated pressures. A mixture of CO and N2 buffer was studied various concentrations in the 101 – 500 kPa total pressure range. The species interest selectively ionized using resonance enhanced multiphoton ionization (REMPI), electron detection performed microwave scattering (MS).