Hypervelocity Dust Particles Research Articles

Charged Particle Pickup Tube Detector Used in Experimental Applications and Classroom Demonstrations

Acharge pickup detector was developed at the University of Colorado for use in classroom demonstrations and in the dust accelerator at the Institute for Modeling Plasma, Atmospheres and Cosmic Dust (IMPACT). The detector can be used in a physics classroom to help high school and introductory-level physics students connect electromagnetic phenomena with measurement techniques that are common to experimental physics and in electronics courses to demonstrate the use of a charge-sensitive amplifier (CSA). Construction of a similar detector would develop students’ basic machining and electronics skills, which are crucial in most undergraduate experimental physics opportunities. The detector is designed to nondestructively determine the velocity and charge of particles. The detector is compact (8.6 cm x 5.4 cm x 4.1 cm), simple, and lightweight. It is built with off-the-shelf components with simple machining, resulting in a low-cost (∼$100) detector that maintains the high sensitivity (0.2 fC) necessary for characterization of most hypervelocity dust particles, as well as a wide variety of other applications accessible to introductory-level physics students such as charged particles in a dust storm, pith balls, or charged raindrops. This paper focuses on both characterization of the detector using the accelerator at IMPACT and the basics of the undergraduate-level physics principles, electronics principles, mechanical design, and lab applications.

Lunar regolith and water ice escape due to micrometeorite bombardment

Dust particles exist everywhere in interplanetary space and they evolve dynamically after their origination from the sources like Asteroid belt, Kuiper belt, comets or space debris left during the formation of solar system. These micrometeorites encounter the inner planets, while they spiral-in towards the Sun. From whichever come to Earth, many particles are ablated in the Earth's atmosphere and leave the metallic ions behind. In case of Moon, all such particles can reach the surface without ablation owing to the absence of atmosphere. Due to the impact of hypervelocity dust particles on lunar surface, ejecta come out in the lunar environment. In some cases, the ejecta velocity could be larger than the escape velocity and particles may be able to escape from Moon. Further, the escaping ejecta may carry water ice (volatiles), whenever incoming projectiles hit the surface in polar region with the water ice present. In this paper, we have computed the ejecta parameters and estimated the possible escape of volatiles from Moon, using Galileo observations of the dust particles near Moon. Considering the incident angle distribution, the upper limit of regolith escape rate is found to be ~2.218 × 10−4 [1.662 × 10−4, 10.232 × 10−4] kg/s. Similarly, the upper limit of water ice escape rate is found to be ~1.988 × 10−7 [1.562 × 10−7, 7.567 × 10−7] kg/s. On one side, Moon is found to be gradually becoming heavier due to its one order higher incoming dust particles than those escaping from it. While on the other side, Moon could be depleted of water ice (volatiles) resources over a period of time, because of the escape due to micrometeorite impact. The results presented here could be useful to understand the dust and volatile escape from Moon.

Do we detect interplanetary dust with Faraday cups?

Transient clouds of a plasma generated by hypervelocity dust particles impacting onto the spacecraft were observed in-situ by many experiments over the last 20 years. The reported observations analyze sensitive measurements of plasma waves that are transmitted to the Earth with a sufficient time resolution. The detection is based on a fact that hypervelocity impacts generate plumes of the ionized gas expanding into a space. The present paper analyzes five years of the operation of the Bright Monitor of the Solar Wind (BMSW) onboard the Spektr-R spacecraft with a motivation to demonstrate that such type of the instruments is capable to observe the dust impacts into its detectors. The results of analysis are compared with Wind electric field measurements used for a detection of hypervelocity dust impacts.

Interplanetary and interstellar dust observed by the Wind/WAVES electric field instrument

Observations of hypervelocity dust particles impacting the Wind spacecraft are reported here for the first time using data from the Wind/WAVES electric field instrument. A unique combination of rotating spacecraft, amplitude‐triggered high‐cadence waveform collection, and electric field antenna configuration allow the first direct determination of dust impact direction by any spacecraft using electric field data. Dust flux and impact direction data indicate that the observed dust is approximately micron‐sized with both interplanetary and interstellar populations. Nanometer radius dust is not detected by Wind during times when nanometer dust is observed on the STEREO spacecraft and both spacecraft are in close proximity. Determined impact directions suggest that interplanetary dust detected by Wind/WAVES at 1 AU is dominated by particles on bound trajectories crossing Earth's orbit, rather than dust with hyperbolic orbits.

Dust detector using piezoelectric lead zirconate titanate with current-to-voltage converting amplifier for functional advancement

This paper describes the concept of a dust monitor using lead zirconate titanate (PZT) ceramics with a large detection area. Its potential as a dust detector is experimentally demonstrated. The dust monitor has a small volume compared to an impact ionization detector with the same detection area, due to the PZT sensor. The PZT sensor, as a traditional device for the in-situ observation of hypervelocity dust particles, has been used for momentum measurement. The hypervelocity impact signals of PZT sensors are typically read by charge-sensitive amplifiers. Instead, we suggest a new method that a current-to-voltage converting amplifier is useful for interpreting the impact signal of a PZT sensor arising from dust particles down to 0.5 μm in radius. We propose that datasets of dust impacts can be obtained with a higher statistical accuracy, if the new method is applied to instruments on forthcoming interplanetary-space-cruising spacecrafts.

A self-consistent picture for hyper-velocity metal dust in FTU

Numerical simulations of the propagation of plasma blobs in the scrape-off layer (SOL) of the Frascati Tokamak Upgrade (FTU) are presented. The maximum distances that a plasma blob may travel in the radial direction are calculated under FTU physical conditions and geometry, taking into account the dissipation due to the presence of dust. It is found that a relatively small amount of nanometre iron dust particles can dissipate blobs before they reach the wall. The amount of dust required is of the same order as, or smaller than, that needed to produce hyper-velocity dust particles, so that a consistent interpretation is reached for experiments in FTU where evidence of the dust impact ionization was reported.

High-speed imaging of dust particles in plasma

AbstractHigh-speed imaging is a powerful tool for studying dusty plasmas. The recorded trajectories of dust particles can provide direct information about the physical processes involved in dust-plasma and dust–dust interactions. A review of some experiments and their imaging techniques employed for tracking dust particles immersed in low-ionized gases and in high-density plasma jets is presented. Digital cameras are used to record the motion of slow or hypervelocity dust particles dragged by plasma jets, or to evidence single or collective dust particle oscillations and vibrations in the plasma sheath.

Novel Diagnostics for Dust in Space, Laboratory and Fusion Plasmas

AbstractIn situ diagnostics for mobile dust, based on dust impact ionization phenomena, as well as silica aerogel dust collectors are discussed for applications to space and fusion plasmas. The feasibility of an electro‐optical probe to detect hypervelocity (>1 km/s) dust particles in tokamaks is evaluated. For quiescent plasmas, a diagnostic of submicron dust based on measurements of plasma fluctuation spectra can be used (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Recent researches on dust in EAST and HT-7 tokamaks

Recently, the formation during plasma, distribution and basic characteristics of dust, such as morphology, size, composition and retention of hydrogen isotopes, were investigated on EAST and HT-7 superconducting tokamaks. It was found that dust in the two devices had similar characteristics. It was also found that plasma parameters, displacement and configuration were main factors for the dust production. Hot spots produced during long pulse were also an important reason for the production of lots of dust particles. A dust capture experiment using SiO2 aerogel probe showed hypervelocity dust particles would exist in HT-7, i.e. vd>1km/s.

Measurements of the terrestrial dust influx variability by the Cosmic Dust Experiment

We report on the results of the Cosmic Dust Experiment (CDE) onboard the Aeronomy of Ice in the Mesosphere (AIM) satellite, collected during eight months of operation between May 2007 and February 2008. CDE is an impact detector designed to measure the variability of the cosmic dust influx of grains with radius, 1.5 < r < 8 μ m . CDE consists of 14 permanently polarized polyvinylidene fluoride (PVDF) channels that produce an electrical signal when impacted with hyper-velocity dust particles. The instrument has a total surface area of 0.11 m 2 and a time resolution of 1 s. CDE experienced higher noise levels than expected on-orbit, triggering the need for new laboratory experiments, as well as the development of new data reduction approaches. We present the first eight months of reduced CDE data, highlighting the observed spatial and temporal variability of the cosmic dust influx.

Development of the Mercury dust monitor (MDM) onboard the BepiColombo mission

In order to clarify the dust environment around Mercury, we have proposed that the Mercury dust monitor (MDM) should be onboard the BepiColombo/Mercury magnetosphere orbiter (MMO). The main objective of the project is to obtain new data on the flux and momentum of the interplanetary meteoroid complex near Mercury (0.31–0.47 AU). The MDM uses lightweight and heat-resistant piezoelectric ceramic sensors made of lead zirconate titanate (PZT). Four square plates of PZT, 40 mm×40 mm×2 mm each, will be installed on a side panel of the MMO. Upon colliding with a dust particle, the piezoelectricity of PZT generates a transient voltage signal. It is easy to determine the time of the impact event from which the incident direction is roughly estimated using the spin angle of the MMO. To extract kinetic information on incident particles from the output signals of the PZT sensor, calibration experiments have been carried out with hypervelocity dust particles from two Van de Graaff dust accelerators at the Max-Planck-Institut für Kernphysik and the University of Tokyo.

Low-charge detector for the monitoring of hyper-velocity micron-sized dust particles

A new low-noise beam detector was developed, assembled and tested for the Heidelberg dust accelerator facility. The detector was used to determine in situ the charge, speed and mass of individual dust grains flying through a highly shielded metal cylinder with a length of 200 mm and integrated with a charge-sensitive amplifier Amptek model A250F/NF. Micron-sized latex and iron particles were fired at speeds between 5 and 50 km s−1. The detector characterizes dust particles with a primary charge of 1 fC, a speed of 20 km s−1 and a size of 0.1 µm with a signal-to-noise ratio of 6. The noise of the integrated detector system is typically 0.15 fC (950 electrons) in a bandwidth from 2 kHz to 10 MHz. The new detector allows the control and selection of particles either with a lower surface potential (low-conductive surfaces of polyaniline-coated polystyrene particles), or smaller grains with very small primary charges (sub-micron-sized grains with speeds above 10 km s−1).

The charge and velocity detector of the cosmic dust analyzer on Cassini

The cosmic dust analyzer aboard the Cassini spacecraft includes a charge and velocity detector which senses electric charges >10 −15 C of individual cosmic dust grains as they enter the instrument. Charge is an important property of each grain, because it affects its orbital dynamics and is a measure of its size. The duration and shape of the charge signal are also important, because they reveal the grain's location and velocity relative to the spacecraft. The velocity, in turn, can be expressed in a heliocentric coordinate system and orbital parameters can be derived and aid in the identification of the grain's origin. We describe the operation of the charge and velocity detector, present results of laboratory calibrations using charged hypervelocity dust particles, show the first dust charge signal obtained from interplanetary space, and discuss potential applications of an advanced charge detector for future space missions.

Two-dimensional position-sensing PVDF dust detectors for measurement of dust particle trajectory, velocity, and mass

We have extended our development of polyvinylidene fluoride (PVDF) dust detectors to include the capability for determination of the x, y coordinates of particle entry into the PVDF detector. The two-dimensional position-sensing PVDF dust detectors ( x, y detectors) we have developed employ resistive charge division, and have a set of conducting strips on the front surface and an orthogonal set on the back surface. Our earlier measurements on PVDF x, y detectors made use of a laser to simulate dust particle impacts. These measurements have recently been extended to include impacts from accelerated dust particles. Two 6 μm thick 58 cm 2 PVDF x, y detectors were placed in a telescope arrangement for measurement of particle time-of-flight, trajectory and fragmentation. We present the dust particle results and show that dust particle impact coordinates are measured by the PVDF x, y detectors with typical errors of −1−3 mm for x and y (over most of the detector sensitive area), confirming the results obtained with the laser. We also show that the model we developed earlier to describe signal pulse generation and the occurrence of anomalous currents (i.e., polarity reversal with time) in Si x, y detectors responding to energetic charged nuclei also applies to PVDF x, y detectors responding to hypervelocity dust particles. Finally, we show that even if particle fragmentation occurs upon penetration of the first x, y detector, particle trajectory is still measured, but with a larger position error (∼ 4–6 mm) in the second x, y detector due to the spread of fragment impact positions on the second x, y detector.

A 90 degrees electrostatic prism for microparticle beam steering on a 2 MV Van der Graaff dust accelerator

The design and construction of a 90 degrees electrostatic prism is described. The device is used to deflect hypervelocity dust particles produced in a horizontal van der Graaff accelerator to simulate micrometeoroid impacts on dusty lunar and asteroidal surfaces where vertical incidence must be provided.

The HEOS 2 and HELIOS micrometeoroid experiments

Two micrometeoroid experiments based on the plasma emission caused by impacting hypervelocity dust particles are described. Since 31 January 1972 the first has been flying on the HEOS 2 satellite orbiting the earth in a highly eccentric polar orbit. The second experiment will be flown in 1974 on the HELIOS probe which will orbit the sun with a perihelion of about 0.3 AU. The aim of these experiments is to measure the mass and speed of micrometeoroids and to determine their approximate orbital elements.