The Freja F3C Cold Plasma Analyzer

Whalen, B. A.; Knudsen, D. J.; Yau, A. W.; Pilon, A. M.; Cameron, T.; Sebesta, Jerry; McEwen, D. J.; Koehler, J. A.; Lloyd, Nicholas; Pocobelli, G.; Laframboise, J. G.; Li, W.; Lundin, R.; Eliasson, L.; Watanabe, Shigeto; Campbell, Gaylon S.

doi:10.1007/978-94-011-0299-5_7

Cited by 7 publications

(9 citation statements)

References 17 publications

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“…The SII differs from the more common “top hat” analyzer [ Carlson et al , 1982] in that its focusing system images the energy distribution (rather than stepping through energy with time), and is optimized for lower‐energy particles [ Whalen et al , 1994; Knudsen et al , 2003]. The resulting particle flux distribution is amplified using a microchannel plate and phosphor screen, then reduced in diameter 3:1 and transferred through a 1‐m‐long coherent fiber‐optic imaging bundle.…”

Section: Mission and Instrumentationmentioning

confidence: 99%

Rocket‐based measurements of ion velocity, neutral wind, and electric field in the collisional transition region of the auroral ionosphere

et al. 2009

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[1] The JOULE-II sounding rocket salvo was launched from Poker Flat Rocket Range into weak pulsating aurora following a moderate substorm at 0345 LT on 19 January 2007. We present in situ measurements of ion flow velocity and electric and magnetic fields combined with neutral wind observations derived from ground observations of in situ chemical tracers. Measured ion drifts in the 150-198 km and 92-105 km altitude ranges are consistent withẼ ÂB motion to within 16 m s À1 rms and with neutral wind velocity to within 20 m s À1 , respectively. From these measurements we have calculated the ratio k of the ion cyclotron and ion collision frequencies, finding k = 1 at an altitude of 118 ± 0.3 km. Using direct measurements of ion current, we calculate the Joule heating rate and Pedersen and Hall conductivity profiles for this moderately active event and find height-integrated values of 390 W km À2 and 0.59 and 2.22 S, respectively. We also find that these values would have errors of up to tens of percent without coincident neutral wind measurements, and presumably more so during more active conditions. Ion flow vectors were measured at a rate of 125 s

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Section: Mission and Instrumentationmentioning

confidence: 99%

Rocket‐based measurements of ion velocity, neutral wind, and electric field in the collisional transition region of the auroral ionosphere

et al. 2009

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“…It was designed for measuring low‐energy (0 < E < 20 eV) ion populations over a 360° × 7° field of view (4π steradians twice per spin period), at a rate of 93 distributions per second. The imager consists of a boom‐mounted energy/arrival‐angle electrostatic Whalen analyzer [ Whalen et al , 1994], coupled to an electro‐optical detection scheme. The sensor's outer skin was biased −2 V with respect to payload ground to ensure that the lowest‐energy particles were drawn into the analyzer.…”

Section: Payload and Instrumentationmentioning

confidence: 99%

Core ion interactions with BB ELF, lower hybrid, and Alfvén waves in the high‐latitude topside ionosphere

et al. 2004

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[1] We present simultaneous observations of ion distribution functions and plasma waves in the high-latitude topside ionosphere (500-1000 km) near local midnight during substorm activation. Using a new instrument, the Suprathermal Ion Imager (SII), we are able to explore two-dimensional ion distribution functions with unprecedented resolution in time (93 s À1 ) and energy, focusing on the lowest-energy core (<1 eV) population and suprathermal extensions thereof. The GEODESIC sounding rocket flew through regions containing broadband extremely low frequency (BB ELF) waves, large-amplitude Alfvén waves, and lower-hybrid solitary structures (LHSS), all of which have been shown previously to correlate with ion heating. However, GEODESIC detected heating only in association with LHSS. Ion distributions in and near LHSS showed acceleration in the direction transverse toB 0 (TAI) with temperatures as high as 5-10 eV, appearing in regions 65 ± 25 m across. TAI were centered on much smaller structures ($20 m across) of depleted plasma density and enhanced perpendicular electric fields from 0.1 to 10 kHz, consistent with observations from previous rocket flights. Also in agreement with previous findings, we find two distinct ion populations inside LHSS. The dominant population is composed of unheated, isotropic ''core'' Maxwellian ions having temperatures comparable to the surrounding ambient plasma, while roughly 10% of the plasma density corresponds to the TAI at pitch angles of 90 ± 5°. We argue that the TAI associated with LHSS is consistent with bulk heating of the core ions, and we describe two scenarios that can lead to the observed two-temperature distributions. The BB ELF wave emissions were correlated with LHSS heating at short scales and anticorrelated with auroral electron precipitation at large scales. The GEODESIC instruments observed no large-scale ion heating in association with BB ELF waves. Similarly, no ion heating was detected in the presence of large-amplitude, short perpendicular wavelength Alfvén waves.

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“…It employs a hemispherical electrostatic analyzer (HEA) in conjunction with a time‐of‐flight (TOF) gate using fast‐switching electrodes and a pair of toroidal electrostatic deflectors (TED) in front of the TOF gate. The HEA design was first implemented on the Freja Cold Plasma Analyzer [ Whalen et al ., ]. The TOF gate was first flown on Nozomi [ Yau et al ., ], but spacecraft propulsion system malfunction precluded its operation in Mars orbit.…”

Section: Sensor Designmentioning

confidence: 99%

Imaging thermal plasma mass and velocity analyzer

Yau

Howarth

2016

JGR Space Physics

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We present the design and principle of operation of the imaging ion mass and velocity analyzer on the Enhanced Polar Outflow Probe (e‐POP), which measures low‐energy (1–90 eV/e) ion mass composition (1–40 AMU/e) and velocity distributions using a hemispherical electrostatic analyzer (HEA), a time‐of‐flight (TOF) gate, and a pair of toroidal electrostatic deflectors (TED). The HEA and TOF gate measure the energy‐per‐charge and azimuth of each detected ion and the ion transit time inside the analyzer, respectively, providing the 2‐D velocity distribution of each major ionospheric ion species and resolving the minor ion species under favorable conditions. The TED are in front of the TOF gate and optionally sample ions at different elevation angles up to ±60°, for measurement of 3‐D velocity distribution. We present examples of observation data to illustrate the measurement capability of the analyzer, and show the occurrence of enhanced densities of heavy “minor” O++, N+, and molecular ions and intermittent, high‐velocity (a few km/s) upward and downward flowing H+ ions in localized regions of the quiet time topside high‐latitude ionosphere.

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The Freja F3C Cold Plasma Analyzer

Cited by 7 publications

References 17 publications

Rocket‐based measurements of ion velocity, neutral wind, and electric field in the collisional transition region of the auroral ionosphere

Rocket‐based measurements of ion velocity, neutral wind, and electric field in the collisional transition region of the auroral ionosphere

Core ion interactions with BB ELF, lower hybrid, and Alfvén waves in the high‐latitude topside ionosphere

Imaging thermal plasma mass and velocity analyzer

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