Laser-induced fluorescence measurement of very slow neutral flows in a dusty plasma experiment

Marshall, Ryan S.; Bellan, Paul M.

doi:10.1063/5.0006684

“…This saturation of α can be seen from the terms containing λ becoming unimportant in Equations (41)-(43) when l b . 3  For the Caltech experiment t ref =8 ms, so the prediction that α is constant for times much greater than 8 ms isconsistent with Figure 4(b) in Marshall & Bellan (2020), which shows the aspect ratio remaining constant at α≈4.5 when a increases from 20 to 80 μm in a 10 s time interval.…”

Section: Modelmentioning

confidence: 81%

Why Interstellar Ice Dust Grains Should Be Elongated

Bellan

¹

2020

ApJ

Self Cite

View full text Add to dashboard Cite

Models of interstellar dust alignment assume that dust grains are elongated, but none of these models explain why dust grains should be elongated. On the other hand, models of interstellar dust grain growth assume that dust grains are spherical and not elongated. We show that when dusty plasma effects and the dipole moment of water molecules are together taken into account, ice grains in interstellar space should be prolate ellipsoids and not spheres. Dusty plasma analysis shows that an ice grain is charged to a negative potential that has magnitude nearly equal to that of the electron temperature. Several different mechanisms causing deviation from sphericity are identified; these mechanisms involve the interaction of the dipole moment of water molecules with electric fields associated with ice grain charging. These mechanisms include the focusing of water molecule trajectories, the migration of water molecules in a quasi-liquid layer on the grain surface toward regions where the electric field is strongest, the enhancement of this migration by the bombardment of energetic protons that gain energy upon falling into the ice grain negative potential, and mutual repulsion by electric charges having the same sign. The aspect ratio is established shortly after the ice grain is formed, and then is maintained as the grain grows.

show abstract

“…[214][215][216]220] Laser-absorption measurements by Pikalev et al [125] show only the evidence of dust-induced gas heating. Marshall et al [157] showed that the LIF measurements suffer from problems with the laser power broadening and absorption of the laser light on its way through the plasma. Solution of these problems could help to directly measure the neutral gas temperature field in a plasma and make a further step in understanding of the dust-induced effects on it.…”

Section: Discussionmentioning

confidence: 99%

“…Application of laser spectroscopy to the investigations of dust-plasma interactions does not have a long history. Nevertheless, several works have been performed on 1s 5 argon metastable atoms [125,149,[157][158][159] and 1s 3 neon metastable atoms. [155] One of the unsolved problems that could lead to significant progress in the investigations of the dust-plasma interactions is the measurement of ion velocity distributions.…”

Section: Laser Spectroscopymentioning

confidence: 99%

“…In the fluorescence configuration, usually termed as laser-induced fluorescence (LIF), the spectral dependence of the plasma fluorescence is measured. The advantage of LIF is its imaging ability, although the so-called laser power saturation issues [156,157] and absorption of the laser beam make it much more difficult to obtain reliable quantitative data compared with LAS.…”

Section: Laser Spectroscopymentioning

confidence: 99%

See 1 more Smart Citation

Physical aspects of dust–plasma interactions

Pustylnik

¹

,

Pikalev

²

,

Zobnin

³

et al. 2021

Contributions to Plasma Physics

View full text Add to dashboard Cite

Low‐pressure gas discharge plasmas are known to be strongly affected by the presence of small dust particles. This issue plays a role in the investigations of dust particle‐forming plasmas, where the dust‐induced instabilities may affect the properties of synthesized dust particles. Also, gas discharges with large amounts of microparticles are used in microgravity experiments, where strongly coupled subsystems of charged microparticles represent particle‐resolved models of liquids and solids. In this field, deep understanding of dust–plasma interactions is required to construct the discharge configurations which would be able to model the desired generic condensed matter physics as well as, in the interpretation of experiments, to distinguish the plasma phenomena from the generic condensed matter physics phenomena. In this review, we address only physical aspects of dust–plasma interactions, that is, we always imply constant chemical composition of the plasma as well as constant size of the dust particles. We also restrict the review to two discharge types: dc discharge and capacitively coupled rf discharge. We describe the experimental methods used in the investigations of dust–plasma interactions and show the approaches to numerical modelling of the gas discharge plasmas with large amounts of dust. Starting from the basic physical principles governing the dust–plasma interactions, we discuss the state‐of‐the‐art understanding of such complicated, discharge‐type‐specific phenomena as dust‐induced stratification and transverse instability in a dc discharge or void formation and heartbeat instability in an rf discharge.

show abstract

“…3 ¯ For the Caltech experiment t ref =8 ms, so the prediction that α is constant for times much greater than 8 ms isconsistent with Figure 4(b) in Marshall & Bellan (2020), which shows the aspect ratio remaining constant at α≈4.5 when a increases from 20 to 80 μm in a 10 s time interval.…”

mentioning

confidence: 81%

Why Interstellar Ice Dust Grains Should be Elongated

Bellan

¹

2020

2020 IEEE International Conference on Plasma Science (ICOPS)

0

View full text Add to dashboard Cite

Models of interstellar dust alignment assume that dust grains are elongated, but none of these models explain why dust grains should be elongated. On the other hand, models of interstellar dust grain growth assume that dust grains are spherical and not elongated. We show that when dusty plasma effects and the dipole moment of water molecules are together taken into account, ice grains in interstellar space should be prolate ellipsoids and not spheres. Dusty plasma analysis shows that an ice grain is charged to a negative potential that has magnitude nearly equal to that of the electron temperature. Several different mechanisms causing deviation from sphericity are identified; these mechanisms involve the interaction of the dipole moment of water molecules with electric fields associated with ice grain charging. These mechanisms include the focusing of water molecule trajectories, the migration of water molecules in a quasi-liquid layer on the grain surface toward regions where the electric field is strongest, the enhancement of this migration by the bombardment of energetic protons that gain energy upon falling into the ice grain negative potential, and mutual repulsion by electric charges having the same sign. The aspect ratio is established shortly after the ice grain is formed, and then is maintained as the grain grows. Unified Astronomy Thesaurus concepts: Very small grains (1770); Interstellar dust processes (838); Laboratory astrophysics (2004); Interstellar magnetic fields (845); Interstellar molecules (849); Interstellar emissions (840); Starlight polarization (1571); Water vapor (1791); Plasma astrophysics (1261); Ice formation (2092)

show abstract

Laser-induced fluorescence measurement of very slow neutral flows in a dusty plasma experiment

Cited by 7 publications

References 21 publications

Why Interstellar Ice Dust Grains Should Be Elongated

Why Interstellar Ice Dust Grains Should Be Elongated

Physical aspects of dust–plasma interactions

Why Interstellar Ice Dust Grains Should be Elongated

Contact Info

Product

Resources

About