Measurement of temperature after hypervelocity collision of microparticles in the range from 10 to 40 km/s

Miyachi, T.; Fujii, Masayuki; Hasebe, Nobuyuki; Miyajima, M.; Okudaira, O.; Takechi, Seiji; Onishi, Toshiyuki; Minami, Shigeyuki; Shibata, Hiromi; Ohashi, Hideo; Iwai, Takeo; Nogami, K.; Sasaki, Sho; Grün, E.; Srama, R.; Okada, Nagaya

doi:10.1063/1.3013313

Cited by 10 publications

(10 citation statements)

References 7 publications

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“…They found, however, that the expansion speed of the emitted cloud is only proportional to the square root of the impactor speed, not directly. More recently, Miyachi et al [2008] have found that the temperature of the emitted cloud is proportional to the impactor velocity, agreeing with the Goller and Grun square root dependence. This weaker dependence on the impactor speed seems to be a result of adiabatic expansion during the collisional phase.…”

Section: Impact Physics-laboratory Measurements and Simulationssupporting

confidence: 78%

Dust impact signals on the wind spacecraft

2016

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We analyze waveforms recorded by the Time Domain Sampler of the WAVES experiment on Wind which are similar to impulsive waveforms observed by the S/WAVES experiment on STEREO. These have been interpreted as dust impacts by Meyer‐Vernet et al. and M. L. Kaiser and K. Goetz and extensively analyzed by Zaslavsky et al. The mechanism for coupling the emission to the antennas to produce an electrical signal is still not well understood, however. One suggested mechanism for coupling of the impact to the antenna is that the spacecraft body changes potential with respect to the surrounding plasma but the antennas do not (the body mechanism). Another class of mechanisms, with several forms, is that the charge of the emitted cloud interacts with the antennas. The Wind data show that both are operating. The time domain shapes of the dust pulses are highly variable but we have little understanding of what provides these shapes. One feature of the STEREO data has been interpreted as impacts from high velocity nanoparticles entrained by the solar wind. We have not found evidence for fast nanodust in the Wind data. An appreciable fraction of the impacts observed on Wind is consistent with interstellar dust. The impact rates do not follow a Poisson distribution, expected for random independent events, and this is interpreted as bunching. We have not succeeded in relating this bunching to known meteor showers, and they do not repeat from 1 year to the next. The data suggest bunching by fields in the heliosphere.

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Section: Impact Physics-laboratory Measurements and Simulationssupporting

confidence: 78%

Dust impact signals on the wind spacecraft

2016

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“…Laboratory measurements and theory yield various and conflicting results, including calculated temperatures of about 1 eV at impact speeds 70–80 km/s [ Hornung and Kissel , ], observed temperatures of a few eV at an impact speed of about 70 km/s [ Krueger and Kissel , ], and in contrast temperatures of 10–60 eV with a weak dependence on impact speed in the range 5–100 km/s [ Ratcliff et al , ]. Subsequent observations yield 0.9–3 eV for impact speeds varying from 10 to 40 km/s [ Miyachi et al , ] and recently below 5 eV for electrons at impact speeds below 20 km/s [ Collette et al , ]. Expansion speeds have been suggested to be of the order of magnitude of the ion thermal speed and to increase with the grain's impact speed, whereas in contrast, Lee et al [] measured v E ≃15–30 km/s for masses m > 10 −17 kg impacting at 3–10 km/s, with no evidence of any variation with impact speed.…”

Section: Risetime Of Pulses In Spacecraft Potential For Nanodust Impactsmentioning

confidence: 99%

Frequency range of dust detection in space with radio and plasma wave receivers: Theory and application to interplanetary nanodust impacts on Cassini

et al. 2017

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Wave instruments can detect dust in space via the charges released by impact ionization of fast dust grains. Each hypervelocity dust impact produces an electrostatic pulse whose short risetime is a major property determining the frequency range of detection. We propose a simplified analytical model to calculate this risetime and its variation with grains' mass and photoelectron or ambient plasma density, for pulses in spacecraft potential due to fast interplanetary nanodust impacts. We test these calculations by analyzing the high‐frequency receiver data of the radio and plasma wave instrument during the cruise phase of the Cassini mission between Earth and Jupiter. These data confirm the dependence of the risetime on grains' mass and speed and heliocentric distance predicted by our calculations. Furthermore, the data show that the nanodust properties follow closely the fluctuations of the solar wind velocity component perpendicular to the magnetic field, as predicted by dynamics. The calculations can be generalized to microdust detection on other spacecraft and might explain previous observations left uninterpreted. These calculations are also relevant for the design of wave receivers, by determining the optimal frequency range for dust detection on future missions.

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“…The top and bottom forms correspond to normal and odd events, respectively. The former form was considered to occur when the flashes during collision were directly recorded by the PM (Miyachi et al, 2008c), while the latter was considered to be a result of the superposition of flashes that occurred outside the sensitive area of the PZT element and possible secondary processes. Only those events for which an isolated single peak appeared (top of Fig.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…In addition, a dust detector designed to measure the cosmic dust around Mercury-Mercury Dust Monitor (MDM)-has been approved (Nogami et al, 2010). The MDM will be onboard the BepiColombo mission.…”

Section: Introductionmentioning

confidence: 99%