Monolithic GaAs Acoustic Charge Transport Devices

Hoskins, M.J.; Hunsinger, B.J.

doi:10.1109/ultsym.1982.197868

Cited by 10 publications

(5 citation statements)

References 6 publications

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“…They occur because of the ageostrophic circulation at the jet entrance (Hoskins 1982) and coincide with the frontal zone beneath the jet. Deep folds can extend down to the top of the boundary layer (Browell et al 1987;Vaughan et al 1994), while smaller folds, extending only into the upper troposphere, are ubiquitous around the polar jet stream (e.g.…”

Section: Introductionmentioning

confidence: 99%

Convective mixing in a tropopause fold

Reid

Vaughan

2004

Quart J Royal Meteoro Soc

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SUMMARYWe present a case study of the passage of a tropopause fold over the UK behind a cold front, with emphasis on the mixing caused by convection extending into the fold. The event took place on 15-16 January 1999, and was the subject of intensive observations using the Met Office C130 aircraft and the mesosphere-stratospheretroposphere (MST) radar at Aberystwyth. Here we concentrate on radar and satellite observations during the afternoon of 16 January, when the surface cold front had passed over the UK. A tongue of moist air moved northeastwards over Wales at 700 hPa at this time, which, because of the very dry air in the fold above, resulted in potential instability. The resulting convection was clearly observed in NOAA satellite images. The MST radar depicted the passage of the cold front and tropopause fold as a layer of high-echo power and vertical wind shear ascending with time. Spectral widths showed the fold to be free of turbulence until 1200 UTC on 16 January, when convection was observed reaching into the frontal zone and generating turbulence. Eddy dissipation and diffusivity rates of 8.6 mW kg −1 and 8.5 m 2 s −1 , respectively, were derived for this event. To place these figures in context, they are compared with corresponding rates derived for sixteen other passages of tropopause folds over the radar, each resulting from shear rather than convective instability. The convective event is found to be comparable to the strongest shear events, and to correspond to moderate turbulence as experienced by an aircraft. This process is of potential importance for atmospheric chemistry because it mixes boundary layer air directly with stratospheric air over a timescale of 1-2 hours.

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Section: Introductionmentioning

confidence: 99%

Convective mixing in a tropopause fold

Reid

Vaughan

2004

Quart J Royal Meteoro Soc

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“…A more detailed circuit is given elsewhere [ 3 ] . The TRAPATT diode [2] ~ mounted in a coaxial line with no tuning slugs, is biased from the variable dc pedestal voltage Vo together with a pulsed output from the pulser. The oscillator was also pulse modulated, triggered by the pulser 1 to ensure appropriate coincidence of the RF and bias pulses.…”

Section: Experimestal Resultsmentioning

confidence: 99%

“…The results of some associated experiments reported in this letter clearly demonstrate that such devices can exhibit a broad-band negative resistance characteristic over the frequency of the oscillator circuit. The existance of such a small-signal negative resistance may be significant in the explanation of the ease of starting and operation of the simple TRAPATT oscillator circuit described by Davies, Newton, and Summers [2] …”

Section: Introductionmentioning

confidence: 99%

“…In this device, buried-channel electron transport is accomplished at the sound velocity using the traveling-wave electric field of a SAW generated directly in the GaAs. Several attractive features associated with the acoustic charge transport (ACT) concept have been discussed [ l ] , [ 2 ] , and a theoretical investigation of transport performance indicates that the ACT device is fundamentally capable of high-speed operation and very high transfer efficiency [ 3 ] , This is primarily because traveling-wave excitation provides a nearly uniform drift field within the transported charge packets for all space and time, so that carrier transfer occurs continuously and entirely under the influence of an electric field.…”

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confidence: 99%

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Experimental performance of the buried-channel acoustic charge transport device

Hoskins

Bogus

Hunsinger

1983

IEEE Electron Device Lett.

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High-speed electron transport is accomplished in a new type of buried-channel charge transfer device which is based on the nonlinear acoustoelectric interaction between large amplitude surface acoustic waves (SAW) and electrons in GaAs. The performance of the acoustic charge transport (ACT) device is enhanced by design improvements which provide precise channel definition and charge injection structures. A transfer efficiency in excess of 0.996 has been measured in an experimental device operating at the SAW clock frequency of 358 MHz.

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“…A more exploratory yet potentially high-performance technology is the acoustic-charge-transport (ACT) device [39]. ACT devices offer CCD-like sampling using SAW for charge transport.…”

Section: Enhancements and Future Directions Device Technologiesmentioning

confidence: 99%