| 1. |
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| 2. |
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| 3. |
- Gruen, E., et al.
(författare)
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Ulysses Dust Detection System V3.1
- 2010
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Ingår i: NASA Planetary Data System. ; 140
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Tidskriftsartikel (refereegranskat)abstract
- This data set contains the data from the Ulysses dust detector system (UDDS) from start of mission through the end of mission, 1990-2007. (As the dust detector was turned off after Nov. 30, 2007, this is the last date for which UDDS data is recorded.) Included are the dust impact data, noise data, laboratory calibration data, and location and orientation of the spacecraft and instrument.
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| 4. |
- Grün, E., et al.
(författare)
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Dust Measurements During Galileo's Approach to Jupiter and Io Encounter
- 1996
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 274:5286, s. 399-401
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Tidskriftsartikel (refereegranskat)abstract
- About a hundred dust impacts per day were detected during the first week in December 1995 by Galileo during its approach to Jupiter. These impacts were caused by submicrometer-sized particles that were just above the detection limit. After the closest approach to Io on 7 December, impacts of these small particles ceased. This effect is expected for dust grains emitted from Io that exit the field of view of the instrument after the flyby. The impact rate of bigger micrometer-sized dust grains continued to increase toward Jupiter. These dust particles are in orbit about Jupiter or are interplanetary grains that are gravitationally concentrated near Jupiter.
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| 5. |
- Grün, E., et al.
(författare)
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Dust measurements in the Jovian magnetosphere
- 1997
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Ingår i: Geophysical Research Letters. - 1944-8007. ; 24:17, s. 2171-2174
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Tidskriftsartikel (refereegranskat)abstract
- Dust measurements have been obtained with the dust detector onboard the Galileo spacecraft inside a distance of about 60RJ from Jupiter (Jupiter radius, RJ = 71,492 km) during two periods of about 8 days around Galileo's closest approaches to Ganymede on 27 June and on 6 Sept 1996. The impact rate of submicrometer-sized particles fluctuated by a factor of several hundred with a period of about 10 hours, implying that their trajectories are strongly affected by the interaction with the Jovian magnetic field. Concentrations of small dust impacts were detected at the times of Ganymede closest approaches that could be secondary ejecta particles generated upon impact of other particles onto Ganymede's surface. Micrometer-sized dust particles, which could be on bound orbits about Jupiter, are concentrated in the inner Jovian system inside about 20RJ from Jupiter.
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| 6. |
- Grün, E., et al.
(författare)
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Galileo observes electromagnetically coupled dust in the Jovian magnetosphere
- 1998
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Ingår i: Journal of Geophysical Research. - 2156-2202. ; 103:E9, s. 20011-20022
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of dust coupled to the Jovian magnetosphere have been obtained with the dust detector on board the Galileo spacecraft. We report on data obtained during the first four orbits about Jupiter that had flybys of the Galilean satellites: Ganymede (orbits 1 and 2), Callisto (orbit 3), and Europa (orbit 4). The most prominent features observed are highly time variable dust streams recorded throughout the Jovian system. The impact rate varied by up to 2 orders of magnitude with a 5 and 10 hour periodicity, which shows a correlation with Galileo's position relative to the Jovian magnetic field. Around 20 RJ (Jupiter radius, RJ=71, 492 km) in bound a dip in the impact rate has been found consistently. At the same times, reversals by 180° in impact direction occurred. This behavior can be qualitatively explained by strong coupling of nanometer-sized dust to the Jovian magnetic field. At times of satellite flybys, enhanced rates of dust impacts have been observed, which suggests that all Galilean satellites are sources of ejecta particles. Inside about 20 RJ impacts of micrometer-sized particles have been recorded that could be particles on bound orbits about Jupiter.
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| 7. |
- Grun, E., et al.
(författare)
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South-North and Radial Traverses through the Interplanetary Dust Cloud
- 1997
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Ingår i: Icarus. - : Elsevier BV. - 0019-1035. ; 129:2, s. 270-288
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Tidskriftsartikel (refereegranskat)abstract
- Identical in situ dust detectors are flown on board the Galileo and Ulysses spacecraft. They record impacts of micrometeoroids in the ecliptic plane at heliocentric distances from 0.7 to 5.4 AU and in a plane almost perpendicular to the ecliptic from -79 deg to +79 deg ecliptic latitude. The combination of both Ulysses and Galileo measurements yields information about the radial and latitudinal distributions of micron- and sub-micron-sized dust in the Solar System. Two types of dust particles were found to dominate the dust flux in interplanetary space. Interplanetary micrometeoroids covering a wide mass range from 10^-16 to 10^-6 g are recorded mostly inside 3 AU and at latitudes below 30 deg. Interstellar grains with masses between 10^-14 and 10^-12 g have been positively identified outside 3 AU near the ecliptic plane and outside 1.8 AU at high ecliptic latitudes (>50 deg). Interstellar grains move on hyperbolic trajectories through the planetary system and constitute the dominant dust flux (1.5 x 10^-4 m^-2 sec^-1) in the outer Solar System and at high ecliptic latitudes. To compare and analyze the Galileo and Ulysses data sets, a new model is developed based on J. Geophys. Res. 98, 17029-17048, Divine's (1993, ``five populations of interplanetary meteoroids'' model. Both models describe the interplanetary meteoroid environment in terms of dust populations on distinct orbits. Taking into account the measured velocities and the effect of radiation pressure on small particles (described by the ratio of radiation pressure force to gravity, beta), we define four populations of meteoroids on elliptical orbits and one population on hyperbolic orbit that can fit the micrometeoroid flux observed by Galileo and Ulysses. Micrometeoroids with masses greater than 10^-10 g and negligible radiation pressure (beta = 0) orbit the Sun on low to moderately eccentric orbits and with low inclinations (<=30 deg). Populations of smaller particles with mean masses of 10^-11 g (beta = 0.3), 10^-13 g (beta = 0.8), and 5 x 10^-15 g (beta = 0.3), respectively, have components with high eccentricities and have increasingly wider inclination distributions with decreasing mass. Similarities among the orbit distributions of the small particle populations on bound orbits suggest that all are genetically related and are part of an overall micrometeoroid complex that prevails in the inner Solar System. The high-eccentricity component of the small particle populations may actually be beta-meteoroids which are not well characterized by our measurements. Our modeling suggests further that the interstellar dust flux is not reduced at Ulysses' perihelion distance (1.3 AU) and that it contributes about 30% of the total dust flux observed there.
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| 8. |
- Krueger, H., et al.
(författare)
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Five years of Ulysses dust data: 2000-2004
- 2006
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Ingår i: Planetary and Space Science. - : Elsevier BV. - 1873-5088 .- 0032-0633. ; 54:9-10, s. 932-956
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Tidskriftsartikel (refereegranskat)abstract
- The Ulysses spacecraft has been orbiting the Sun on a highly inclined ellipse (i = 79 degrees, perihelion distance 1.3 AU, aphelion distance 5.4 AU) since it encountered Jupiter in 1992. Between January 2000 and December 2004, the spacecraft completed almost an entire revolution about the Sun, passing through perihelion in May 2001 and aphelion in July 2004. In this five-year period the dust detector on board recorded 4415 dust impacts. We publish and analyse the complete data set of both raw and reduced data for particles with masses 10(-16) g <= M <= 10(-7) g. Together with. 1695 dust impacts recorded between launch of Ulysses and the end of 1999 published earlier (Grain, E., Baguhl, M., Divine, N., Fechtig, H., Hamilton, D.P, Harmer, M.S., Kissel, J., Lindblad, B.A., Linkert, D., Linkert, G., Mann, L, McDonnell, J.A.M., Morfill, G.E., Polanskey, C., Riemann, R., Schwehm, G.H., Siddique, N., Staubach, P., Zook, H.A., 1995a. Two years of Ulysses dust data. Planetary Space Sci. 43, 971-999, Paper III; Kruger, H., Grun, E., Landgraf, M., Baguhl, M., Dermott, S.F., Fechtig, H., Gustafson, B.A., Hamilton, D.P., Harmer, M.S., Horanyi, M., Kissel, J., Lindblad, B., Linkert, D., Linkert, G., Mann, L, McDonnell, J.A.M., Morfill, G.E., Polanskey, C., Schwehm, G.H., Srama, R., Zook, H.A., 1995. Three years of Ulysses dust data: 1993 to 1995. Planetary and Space Sci. 47, 363-383, Paper V; Kruger, H., Grun, E., Landgraf, M., Dermott, S.F., Fechtig, H., Gustafson, B.A., Hamilton, D.P., Harmer, M.S., Horanyi, M., Kissel, J., Lindblad, B., Linkert, D., Linkert, G., Mann, I., McDonnell, J.A.M., Morfill, G.E., Polanskey, C., Schwehm, G.H., Srama, R., Zook, H.A., 2001b. Four years of Ulysses dust data: 1996 to 1999. Planetary Space Sci. 49, 1303-1324, Paper VII), a data set of 6110 dust impacts detected with the Ulysses sensor between October 1990 and December 2004 is now available. The impact rate measured between 2000 and 2002 was relatively constant with about 0.3 impacts per day showing a maximum at 1.5 per day around ecliptic plane crossing in early-2001. The impact direction of the majority of impacts between 2000 and 2002 is compatible with particles of interstellar origin, the rest are most likely interplanetary particles. In 2003 and 2004 dust stream particles originating from the jovian system dominated the overall impact rate. Twenty-two individual dust streams were measured between November 2002 and December 2004. The observed impact rates are compared with models for interplanetary and interstellar dust. The dust measurements from the entire mission since Ulysses launch give good agreement with the interplanetary flux model of Staubach, P., Grun, E., Jehn, R., 1997. The meteoroid environment near Earth, Adv. Space Res. 19, 301-308. (c) 2006 Elsevier Ltd. All rights reserved.
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| 9. |
- Krueger, H., et al.
(författare)
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Galileo dust data from the jovian system: 1997-1999
- 2006
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Ingår i: Planetary and Space Science. - : Elsevier BV. - 1873-5088 .- 0032-0633. ; 54:9-10, s. 879-910
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Tidskriftsartikel (refereegranskat)abstract
- The dust detector system on board the Galileo spacecraft recorded dust impacts in circumjovian space during the craft's orbital mission about Jupiter. This is the eighth in a series of papers dedicated to presenting Galileo and Ulysses dust data. We present data from the Galileo dust instrument for the period January 1997-December 1999 when the spacecraft completed 21 revolutions about Jupiter. In this time interval data were obtained as high resolution realtime science data or recorded data during 449 days (representing 41% of the entire period), or via memory readouts during the remaining times. Because the data transmission rate of the spacecraft was very low, the complete data set (i.e. all parameters measured by the instrument during impact of a dust particle) of only 3% (7625) of all particles detected could be transmitted to Earth; the other particles were only counted. Together with the data of 2883 particles detected during, Galileo's interplanetary cruise and 53 53 particles detected in the jovian system in 1996, complete data of 15 861 particles detected by the Galileo dust instrument from 1989 to 1999 are now available. The majority of the detected particles were tiny grains (about 10 nm in radius), most of them originating from Jupiter's innermost Galilean moon Io. They were detected throughout the jovian system and the highest impact rates exceeded 100 min(-1) (C21 orbit; 01 July 1999). With the new data set the times of onset, cessation and a 180 degrees shift in the impact direction of the grains measured during 19 Galileo orbits about Jupiter are well reproduced by simulated 9 nm particles charged up to a potential of +3 V, confirming earlier results obtained for only two Galileo orbits (Horanyi, M., Grun, E., Heck, A., 1997. Modeling the Galileo dust measurements at Jupiter. Geophys. Res. Lett. 24, 2175-2178). Galileo has detected a large number of bigger particles mostly in the region between the Galilean moons. The average radius of 370 of these grains measured in the 1996-1999 period is about 2 mu m (assuming spherical grains with density 1 g cm(-3)) and the size distribution rises steeply towards smaller grains. The biggest detected particles have a radius of about 10 mu m. (c) 2006 Elsevier Ltd. All rights reserved.
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| 10. |
- Krüger, H., et al.
(författare)
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Four years of Ulysses dust data: 1996-1999
- 2001
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Ingår i: Planetary and Space Science. - 1873-5088. ; 49:13, s. 1303-1324
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Tidskriftsartikel (refereegranskat)abstract
- The Ulysses spacecraft is orbiting the Sun on a highly inclined ellipse(/i=79°, perihelion distance 1.3 AU, aphelion distance 5.4 AU).Between January /1996 and December /1999 the spacecraft was beyond 3 AUfrom the Sun and crossed the ecliptic plane at aphelion in May /1998. Inthis 4-yr period 218 dust impacts were recorded with the dust detectoron board. We publish and analyse the complete data set of both raw andreduced data for particles with masses10-16-10-8g. Together with 1477 dust impactsrecorded between launch of Ulysses and the end of /1995 publishedearlier (Grün et al., Planet. Space Sci. 43 (/1995a) 971;Krüger et al., Planet. Space Sci. 47 (/1999b) 363), a data set of1695 dust impacts detected with the Ulysses sensor between October /1990and December /1999 is now available. The impact rate measured between1996 and 1999 was relatively constant with about 0.2 impacts per day.The impact direction of the majority of the impacts is compatible withparticles of interstellar origin, the rest are most likelyinterplanetary particles. The observed impact rate is compared with amodel for the flux of interstellar dust particles. The flux of particlesseveral micrometres in size is compared with the measurements of thedust instruments on board Pioneer 10 and Pioneer 11 beyond 3 AU (Humes,J. Geophys. Res. 85 /(1980) 5841). Between 3 and 5 AU, Pioneer resultspredict that Ulysses should have seen 5 times more (~10mum sized)particles than actually detected.
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| 11. |
- Krüger, H., et al.
(författare)
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One year of Galileo dust data from the Jovian system: 1996
- 2001
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Ingår i: Planetary and Space Science. - 1873-5088. ; 49:13, s. 1285-1301
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Tidskriftsartikel (refereegranskat)abstract
- The dust detector system onboard Galileo has recoding dust impacts incircumjovian space since the spacecraft was injected into a bound orbitabout Jupiter in December 1995. This is the sixth in a series of papersdedicated to presenting Galileo and Ulysses dust data. We present datafrom the Galileo dust instrument for the period January to December 1996when the spacecraft completed four orbits about Jupiter (G1, G2, C3 andE4). Data were obtained as high-resolution realtime science data orrecorded data during a time period of 100 days, or via memory read-outsduring the remaining times. Because the data transmission rate of thespacecraft is very low, the complete data set (i.e. all parametersmeasured by the instrument during impact of a dust particle) for only 2%(5353) of all particles detected could be transmitted to Earth; theother particles were only counted. Together with the data for 2883particles detected during Galileo's interplanetary cruise and publishedearlier, complete data of 8236 particles detected by the Galileo dustinstrument from 1989 to 1996 are now available. The majority ofparticles detected are tiny grains (about 10nm in radius) originatingfrom Jupiter's innermost Galilean moon Io. These grains have beendetected throughout the Jovian system and the highest impact ratesexceeded 100min-1. A small number of grains has been detectedin the close vicinity of the Galilean moons Europa, Ganymede andCallisto which belong to impact-generated dust clouds formed by (mostlysubmicrometer sized) ejecta from the surfaces of the moons (Krügeret al., /1999e. Nature 399, 558). Impacts of submicrometer to micrometersized grains have been detected throughout the Jovian system andespecially in the region between the Galilean moons.
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| 12. |
- Krüger, H., et al.
(författare)
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Three years of Galileo dust data. II. 1993-1995
- 1999
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Ingår i: Planetary and Space Science. - 1873-5088. ; 47:1-2, s. 85-106
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Tidskriftsartikel (refereegranskat)abstract
- Between January 1993 - December 1995, the Galileo spacecraft traversed the interplanetary space between Earth and Jupiter and arrived at Jupiter on 7 December 1995. The dust instrument onboard the spacecraft was operating during most of the time and data from the instrument were obtained via memory readouts which occurred at rates between twice per day and once per week. All events were classified by an onboard program into 24 categories. Noise events were usually restricted to the lowest categories (class 0). During Galileo's passage through Jupiter's radiation belts on 7 December 1995, several of the higher categories (classes 1 and 2) also show evidence for contamination by noise. The highest categories (class 3) were noise-free all the time. A relatively constant impact rate of interplanetary and interstellar (big) particles of 0.4 impacts per day was detected over the whole three-year time span. In the outer solar system (outside about 2.6 AU) they are mostly of interstellar origin, whereas in the inner solar system they are mostly interplanetary particles. Within about 1.7 AU from Jupiter intense streams of small dust particles were detected with impact rates of up to 20,000 per day whose impact directions are compatible with a Jovian origin. Two different populations of dust particles were detected in the Jovian magnetosphere: small stream particles during Galileo's approach to the planet and big particles concentrated closer to Jupiter between the Galilean satellites. Information about 2883 particles detected by the dust instrument during Galileo's six-year journey to Jupiter is now available.
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| 13. |
- Krüger, H., et al.
(författare)
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Three years of Ulysses dust data: 1993-1995
- 1999
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Ingår i: Planetary and Space Science. - 1873-5088. ; 47:3-4, s. 363-383
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Tidskriftsartikel (refereegranskat)abstract
- The Ulysses spacecraft is orbiting the Sun on a highly inclined ellipse (i = 79°). After its Jupiter flyby in 1992 at a heliocentric distance of 5.4 AU, the spacecraftreapproached the inner solar system, flew over the Suns south polar region in September 1994,crossed the ecliptic plane at a distance of 1.3 AU in March 1995, and flew over the Suns northpolar region in July 1995. We report on dust impact data obtained with the dust detector onboardUlysses between January 1993 and December 1995. We publish and analyse the complete dataset of 509 recorded impacts of dust particles with masses between 10-16 g-10-7 g. Together with 968 dust impacts from launch until the end of 1992 published earlier ([Gruuml;n et al., 1995c]), information about 1477 particles detected with theUlysses sensor between October 1990 and December 1995 is now available. The impact ratemeasured between 1993 and 1995 stayed relatively constant at about 0.4 impacts per day andvaried by less than a factor of ten. Most of the impacts recorded outside about 3.5 AU arecompatible with particles of interstellar origin. Two populations of interplanetary particles havebeen recognized: big micrometer-sized particles close to the ecliptic plane and smallsub-micrometer-sized particles at high ecliptic latitudes. The observed impact rate is comparedwith a model for the flux of interstellar dust particles which gives relatively good agreement withthe observed impact rate. No change in the instruments noise characteristics or degradation of thechanneltron could be revealed during the three-year period.
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| 14. |
- Ratynskaia, Svetlana V., et al.
(författare)
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Observation of the effects of dust particles on plasma fluctuation spectra
- 2007
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 99:7
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Tidskriftsartikel (refereegranskat)abstract
- Charged dust particles are theoretically expected to modify the amplitude and spectrum of plasma fluctuations, and this can eventually provide novel diagnostic tools. Direct experimental evidence of the effects of dust particles on the fluctuations of a low collisionality plasma is reported, in agreement with the expectations of kinetic theory.
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| 15. |
- Castaldo, C., et al.
(författare)
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Diagnostics of fast dust particles in tokamak edge plasmas
- 2007
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 47:7, s. L5-L9
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Tidskriftsartikel (refereegranskat)abstract
- The use of electrostatic probes as a diagnostic tool of the dust particles in the tokamak edge plasmas is investigated. Probe measurements of electrostatic fluctuations in the scrape-off layer of the Frascati Tokamak Upgrade revealed that some features of the signals can be explained only by a local non-propagating phenomenon. These signal features are shown to be both in qualitative and quantitative agreement with ionization, and consequent extra charge collected by the probes, due to the impact of micrometre-sized dust at a velocity of the order of 10 km s(- 1). Electron microscope analysis of the probe surface yielded direct support for such an interpretation.
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| 16. |
- Krueger, H., et al.
(författare)
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Galileo Dust Detection System V4.1
- 2010
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Ingår i: NASA Planetary Data System. ; 139
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Tidskriftsartikel (refereegranskat)abstract
- This data set contains the data from the Galileo dust detector system (GDDS) from start of mission through the end of mission. Included are the dust impact data, noise data, laboratory calibration data, and location and orientation of the spacecraft and instrument.
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| 17. |
- Annibaldi, S. V., et al.
(författare)
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Dust-acoustic dispersion relation in three-dimensional complex plasmas under microgravity
- 2007
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- A series of dedicated experiments with the Plasma Kristal Experiment ( PKE)-Nefedov ( Nefedov et al 2003 New J. Phys. 5 33) set-up were performed on board the International Space Station to measure the dispersion relation ( DR) for the longitudinal dust-acoustic ( DA) waves in quasi-isotropic three-dimensional ( 3D) complex plasmas. The waves were excited by applying ac electric modulation of variable frequency to the radio frequency ( rf) electrodes. The amplitude of excitation was varied with frequency to ensure a 'sufficiently linear' regime of the dust density perturbations. The DR was obtained by measuring the induced density perturbations, revealing fairly good agreement with a simple multispecies theory of DA waves.
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| 18. |
- Khrapak, S. A., et al.
(författare)
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Grain charging in an intermediately collisional plasma
- 2012
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Ingår i: Europhysics letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 97:3, s. 35001-
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Tidskriftsartikel (refereegranskat)abstract
- The charges of mu m-size particles in the quasineutral bulk plasma of a dc discharge are determined experimentally in a pressure range between 100 and 500 Pa, spanning the transition between the weakly collisional and highly collisional (hydrodynamic) regimes, where the ion mean free path drops below the plasma screening length. The charge is determined using the force balance condition from the measured particle drift velocities in stable particle flows. A simple interpolation formula for the ion flux to the grain in the transitional regime is shown to fit quite well the experimental results.
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| 19. |
- Khrapak, S. A., et al.
(författare)
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Particle charge in the bulk of gas discharges
- 2005
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Ingår i: Physical Review E. - 1539-3755. ; 72:1
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Tidskriftsartikel (refereegranskat)abstract
- An experimental determination of particle charge in a bulk dc discharge plasma covering a wide range of neutral gas pressures, was recently reported [S. Ratynskaia , Phys. Rev. Lett. 93, 085001 (2004)]. The charges obtained were several times smaller than the predictions of collisionless orbital motion limited theory. This discrepancy was attributed to the effect of ion-neutral collisions. In the present paper a more detailed description of this experiment is provided and additional experimental results obtained with particles of different sizes are reported. The measurements are compared with molecular dynamics simulations of particle charging for conditions similar to those of the experiment, with other available experimental data on particle charge in the bulk of gas discharges, and with a simple analytical model accounting for ion-neutral collisions. All the considered evidence indicates that ion-neutral collisions represent a very important factor, which significantly affects (reduces) the particle charge under typical discharge conditions.
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| 20. |
- Ratynskaia, Svetlana V., et al.
(författare)
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In situ dust detection in fusion devices
- 2008
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 50:12, s. 124046-
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Tidskriftsartikel (refereegranskat)abstract
- Diagnostics for monitoring dust in tokamaks during plasma discharges, both established and currently being developed, are discussed with a focus on the range of dust parameters they can detect. Visible imaging can currently be used for dust particles bigger than a few mu m and velocities below 1 km s(-1). The dust impact ionization phenomenon can be used for the detection of particles with velocities above a few km s(-1). Laser light scattering gives an insight into the amount of sub-micron dust. Aerogels, light porous materials, allow capturing of dust particles without destroying them and determining their velocity. Other methods include the microbalance technique and electrostatic dust detectors. A recent suggestion to use the effects of dust on collective scattering for diagnostic purposes is also discussed.
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| 21. |
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| 22. |
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| 23. |
- Ratynskaia, Svetlana V., et al.
(författare)
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Dust mode in collisionally dominated complex plasmas with particle drift
- 2004
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Ingår i: IEEE Transactions on Plasma Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0093-3813 .- 1939-9375. ; 32:2, s. 613-616
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Tidskriftsartikel (refereegranskat)abstract
- Experiments with flow of microparticles were conducted in a de discharge. A sharp threshold in the neutral gas pressure for the onset of an unstable low-frequency dust wave mode was observed. Highly space- and time-resolved measurements of the microparticle flow combined with probe measurements of the plasma parameters have allowed detailed comparison with a theoretical model. The model demonstrates good qualitative and quantitative agreement with the experimental results providing accurate estimates of the particle charge.
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| 24. |
- Ratynskaia, Svetlana V., et al.
(författare)
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Electrostatic interaction between dust particles in weakly ionized complex plasmas
- 2006
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 13:10
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Tidskriftsartikel (refereegranskat)abstract
- The electrostatic potential around a dust particle in a complex plasma is calculated, taking into account ion-neutral collisions and collective effects, in a range of plasma parameters relevant for typical laboratory experiments. The existence of attractive wells and dependence of their shape on the main experimental control parameters, neutral gas pressure, and dust number density, is investigated.
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| 25. |
- Ratynskaia, Svetlana V., et al.
(författare)
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Experimental determination of dust-particle charge in a discharge plasma at elevated pressures
- 2004
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 93:8
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Tidskriftsartikel (refereegranskat)abstract
- The charge of dust particles is determined experimentally in a bulk dc discharge plasma in the pressure range 20-100 Pa. The charge is obtained by two independent methods: one based on an analysis of the particle motion in a stable particle flow and another on an analysis of the transition of the flow to an unstable regime. Molecular-dynamics simulations of the particle charging for conditions similar to those of the experiment are also performed. The results of both experimental methods and the simulations demonstrate good agreement. The charge obtained is several times smaller than predicted by the collisionless orbital motion theory, and thus the results serve as an experimental indication that ion-neutral collisions significantly affect particle charging.
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| 26. |
- Ratynskaia, Svetlana V., et al.
(författare)
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Hypervelocity dust impacts in FTU scrape-off layer
- 2008
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 48:1
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Tidskriftsartikel (refereegranskat)abstract
- The first evidence of dust-impact ionization processes in the scrape-off layer of the Frascati tokamak upgrade (FTU) was reported in Nucl. Fusion 47 L5 (2007). In this work an extended data analysis (both of electrostatic probe signals and probe surface analysis) is presented, using results of empirical studies of hypervelocity impacts. Within the accuracy and limits of application of such results to tokamak plasma environment, the data are shown to be consistent with occurrence of impacts by micrometre size iron particles at velocities of the order of 10 km s(-1).
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| 27. |
- Ratynskaia, Svetlana V., et al.
(författare)
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Superdiffusion and viscoelastic vortex flows in a two-dimensional complex plasma
- 2006
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 96:10
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Tidskriftsartikel (refereegranskat)abstract
- Viscoelastic vortical fluid motion in a strongly coupled particle system has been observed experimentally. Optical tracking of particle motion in a complex plasma monolayer reveals high grain mobility and large scale vortex flows coexistent with partial preservation of the global hexagonal lattice structure. The transport of particles is superdiffusive and ascribed to Levy statistics on short time scales and to memory effects on the longer scales influenced by cooperative motion. At these longer time scales, the transport is governed by vortex flows covering a wide spectrum of temporal and spatial scales.
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| 28. |
- Ratynskaia, Svetlana V., et al.
(författare)
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Transport in strongly coupled two-dimensional complex plasmas : Role of the interaction potential
- 2007
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Observations of particle motion in a complex plasma monolayer in rf discharge have revealed anomalous dependence on neutral gas pressure; an immobile system at high gas pressures, then, decreasing the pressure, a state with viscoelastic vortical fluid motions and, hence, dramatically enhanced transport, followed again by an ordered state. While the inhibited transport at higher pressures can be attributed to dissipation on neutrals, the transition of the system back to an ordered state at lower pressures has been explained by an increase of the dust-dust viscous dissipation due to significant modifications of the interaction potential between the particles.
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| 29. |
- Shukla, Nitin, et al.
(författare)
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Amplification of magnetic fields by polaritonic flows in quantum pair plasmas
- 2007
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Ingår i: Journal of Plasma Physics. - : Cambridge University Press. - 0022-3778 .- 1469-7807. ; 73, s. 289-293
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Tidskriftsartikel (refereegranskat)abstract
- It is shown that equilibrium polaritonic flows can amplify magnetic fields in an ultra-cold quantum electron–positron/hole (polaritons) plasma. For this purpose, a linear dispersion relation has been derived by using the quantum generalized hydrodynamic equations for the polaritons, the Maxwell equation, and Faraday's law. The dispersion relation admits purely growing instabilities, the growth rates of which are proportional to the equilibrium streaming speeds of the polaritons. Possible applications of our work to the spontaneous excitation of magnetic fields and the associated cross-field transport of the polaritons in micromechanical systems, compact dense astrophysical objects (e.g. neutron stars), and intense laser–plasma interaction experiments are mentioned.
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| 30. |
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| 31. |
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| 32. |
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| 33. |
- Thoma, M. H., et al.
(författare)
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Parabolic flight experiments with PK-4
- 2006
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Ingår i: Microgravity, science and technology. - 0938-0108 .- 1875-0494. ; 18:04-mar, s. 47-50
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Tidskriftsartikel (refereegranskat)abstract
- PK-4 is an experiment designed to investigate complex plasmas (low-temperature plasmas containing microparticles, e.g. dust grains) in a combined dc/rf discharge under microgravity conditions on board of the International Space Station. Within the 35th and 36th ESA parabolic flight campaigns first experiments under microgravity conditions in a specially designed experiment set-up have been performed. The particle flow inside the tube, the appearance of dust waves, and lane formation in interpenetrating particle clouds have been observed.
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| 34. |
- Yaroshenko, V., et al.
(författare)
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Determination of the ion-drag force in a complex plasma
- 2005
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 12:9
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Tidskriftsartikel (refereegranskat)abstract
- The ion-drag force acting on dust particles in the positive column of a dc discharge is measured in the pressure range of 20-120 Pa. The force is obtained by a method which does not require a priori knowledge of the particle charge, but uses the charge gradient determined from the same experiment. The method depends only on two experimentally determined quantities: the particle drift velocity and the electric field. The comparison of experimental results with theoretical models is presented and discussed.
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| 35. |
- Yaroshenko, V.V., et al.
(författare)
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Characteristics of charged dust inferred from the Cassini RPWS measurements in the vicinity of Enceladus
- 2009
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Ingår i: Planetary and Space Science. - : Elsevier BV. - 0032-0633 .- 1873-5088. ; 57:14-15, s. 1807-1812
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Tidskriftsartikel (refereegranskat)abstract
- The data obtained by the Cassini Radio and Plasma Wave Science (RPWS) instrument during the shallow (17.02.2005) and the steep (14.07.2005) crossings of the E-ring revealed a considerable electron depletion in proximity to Enceladus's orbit (the difference between the ion and electron densities can reach similar to 70 cm(-3)). Assuming that this depletion is a signature of the presence of charged dust particles, the main characteristics of dust down to submicron sized particles are derived. The differential size distribution is found to be well described by a power law with an index mu similar to 5.5-6 for the lower size limit a(min) = 0.03 mu m and mu similar to 7.3-8 for a(min) = 0.1 mu m. The calculated average integral dust number density is weakly affected by values of mu and a(min). For a greater than or similar to 0.1 mu m, both flybys gave the maximum dust density about 0.1-0.3 cm(-3) in the vicinity of Enceladus. Our results imply that the dust structure near Enceladus is characterized by approximately the same vertical length scale of 8000 km and reaches a maximum at the same radial distance (displaced outward of the orbit of Enceladus) as found by Kempf et al. [2008. The E-ring in the vicinity of Enceladus. Spatial distribution and properties of the ring particles. Icarus 193, 420-437], from the dust impact data.
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| 36. |
- Yaroshenko, V. V., et al.
(författare)
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Measurements of the dust-ion momentum transfer frequency and ion drag force in complex plasmas
- 2005
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Ingår i: Contributions to Plasma Physics. - : Wiley. - 0863-1042 .- 1521-3986. ; 45:04-mar, s. 223-228
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Tidskriftsartikel (refereegranskat)abstract
- A simple self-consistent method to estimate the effect of the streaming ions on microparticles in a positive column of a dc discharge plasma is presented. The momentum transfer frequency in dust-ion collisions and the ion drag force are determined within a wide range of gas pressures, p = 20 - 120 Pa. The method does not require a priory knowledge of the particle charge, but involves only the particle charge gradient which is recovered from the same experimental data. The method depends only on two experimental quantities: dust particle drift velocity and electric field, thus minimizing the errors in the estimates. Reasonable agreement is found between our force measurements and theoretical predictions, corresponding to the regime of moderate ion-dust particle coupling.
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