PDV-based estimation of ejecta particles’ mass-velocity function from shock-loaded tin experiment

Abstract

A metallic tin plate with a given surface finish of wavelength λ ≃ 60 μm and amplitude h ≃ 8 μm is explosively driven by an electro-detonator with a shock-induced breakout pressure PSB = 28 GPa (unsupported). The resulting dynamic fragmentation process, the so-called “micro-jetting,” is the creation of high-speed jets of matter moving faster than the bulk metallic surface. Hydrodynamic instabilities result in the fragmentation of these jets into micron-sized metallic particles constituting a self-expanding cloud of droplets, whose areal mass, velocity, and particle size distributions are unknown. Lithium-niobate-piezoelectric sensor measured areal mass and Photonic Doppler Velocimetry (PDV) was used to get a time-velocity spectrogram of the cloud. In this article, we present both experimental mass and velocity results and we relate the integrated areal mass of the cloud to the PDV power spectral density with the assumption of a power law particle size distribution. Two models of PDV spectrograms are described. The first one accounts for the speckle statistics of the spectrum and the second one describes an average spectrum for which speckle fluctuations are removed. Finally, the second model is used for a maximum likelihood estimation of the cloud’s parameters from PDV data. The estimated integrated areal mass from PDV data is found to agree well with piezoelectric results. We highlight the relevance of analyzing PDV data and correlating different diagnostics to retrieve the physical properties of ejecta particles.

Dynamics behavior of porous tin under strong shockwave impact

“…强冲击作用下的金属材料动态破碎过程, 既包含 简单的单次加载微喷、层裂/微层裂破碎 [1][2][3][4][5][6][7][8][9][10][11][12][13] , 也有复 杂多次加载产生的表面微射流、主体区域反复冲击再 破碎、主体区域对微射流颗粒回收等一系列复杂过 程 [14][15][16] , 是耦合材料特性、加载状态、样品初始状态 等多因素的复杂多尺度问题, 在惯性约束核聚变、冲 击防护等领域有重要的工程价值和科学意义, 最近几 十年被广泛研究 [17][18][19] .…”

Reconstruction and interpretation of photon Doppler velocimetry spectrum for ejecta particles from shock-loaded sample in vacuum

“…10,11 Many experimental approaches have attempted to measure the ejection production, such as the Asay foil, 3,12 foam recovery, 13 piezoelectric probes, 4,14 Fraunhofer holography, 15,16 X-ray/proton radiography, 2,17 Mie scattering, 17,18 , and photon Doppler velocimetry (PDV). [19][20][21][22][23][24][25] The main quantities of interest are the particles' velocity, diameter, and total area mass. Most approaches can only measure some of these ejecta parameters.…”

“…However, in realworld conditions, these approaches are hard to apply simultaneously because of limitations on the experimental space or configuration. Recently, PDV has attracted considerable attention 21,22,25 owing to its ability to recover the total area mass and the distributions of particle velocity and diameter at the same time. In addition, the light path of PDV is rather concise and its application is convenient.…”

“…Fedorov et al 24 discussed the influence of different particle sizes on the spectrogram boundary in further detail. Recently, Franzkowiak et al 22 and Andriyash et al 21,25 reconstructed the light field of ejecta and obtained the simulated PDV spectrum using single-and multiple-scattering theory, respectively. They varied the particles' parameters and fitted the simulated PDV spectrum to the experimental data.…”

“…Franzkowaik et al 22 and Andriyash et al 21,25 proposed similar approaches for recovering the ejecta parameters from the PDV spectrum through reconstruction and then fitting. However, some assumptions were introduced in the reconstruction of the light field.…”