Search NASA⌕ Search

SEARCH · Search NASA

Results for “RADIO ELECTRONICS”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Rocket radio measurement of electron density in the nighttime ionosphere

One experimental technique based on the Faraday rotation effect of radio waves is presented for measuring electron density in the nighttime ionosphere at midlatitudes. High frequency linearly-polarized radio signals were transmitted to a linearly-polarized receiving system located in a spinning rocket moving through the ionosphere. Faraday rotation was observed in the reference plane of the rocket as a change in frequency of the detected receiver output. The frequency change was measured and the information was used to obtain electron density data. System performance was evaluated and some sources of error were identified. The data obtained was useful in calibrating a Langmuir probe experiment for electron density values of 100/cu cm and greater. Data from two rocket flights are presented to illustrate the experiment.

Gilchrist, B. E.↗
DOE OSTI2021

Electron dynamics in radio frequency magnetron sputtering argon discharges with a dielectric target

Abstract We demonstrate a self-consistent and complete description of electron dynamics in a typical electropositive radio frequency magnetron sputtering (RFMS) argon discharge with a dielectric target. The electron dynamics, including the electron power absorption dynamics in one radio frequency (RF) period, is studied via a fully kinetic 2d3v particle-in-cell/Monte Carlo collision (PIC/MCC) electrostatic simulation. The interplay between the fundamental plasma parameters is analyzed through their spatiotemporal dynamics. Due to the influence of magnetic trap on the electron transport, a spatially dependent charging that perturbs the electric potential is observed on the dielectric target surface, resulting in a spatially dependent ion energy distribution along the target surface. The E × B drift-to-discharge current ratio is in approximate agreement with Bohm diffusion. The electron power absorption can be primarily decoupled into the positive Ohmic power absorption in the bulk plasma region and the negative pressure-induced power absorption near the target surface. Ohmic power absorption is the dominant electron power absorption mechanism, mostly contributed by the azimuthal electron current. The power absorption due to electron inertial effects is negligible on time-average. Both the maximum power absorption and dissipation of electrons appear in the bulk plasma region during the second half of the RF period, implying a strong electron trapping in magnetron discharges. The contribution of secondary electrons is negligible under typical RFMS discharge conditions.

Physics↗
DOE OSTI2019

PART 2: Initial Beam Dynamics Results of an Integrated and Compact 1.3 GHZ Superconducting Radio Frequency (SRF) Electron Source

This paper is the continuation of a technical paper which is called “Detailed Electromagnetic Design of an Integrated and Compact 1.3 GHz Superconducting Radio Frequency (SRF) Electron Source” [1]. In the previous paper, we examined if a promising RF electromagnetic design of the gun and cathode region could be achieved. Further, we examined if this gun region could be fully integrated, in terms of the electromagnetic RF design, with the rest of the accelerator, keeping in mind the overall goal of compactness and reduction of duplicative infrastructure commonly associated with separated function electron guns and structures. While we convinced ourselves thus far that the RF electromagnetic design of our concept is feasible, we also needed to perform particle tracking to assess the beam properties through the entire system, understand and remediate any beam loss. For this step, we examined the cathode region and analyzed the gating process of the thermionic cathode, as losses would most likely be attributed to releasing electrons into the accelerating structure during an unfavorable phase window.

43 PARTICLE ACCELERATORS↗
NASA NTRS1977

Cosmic-ray electrons and galactic radio emission - A conflict

An analysis which takes into account the observed energy spectrum of cosmic-ray electrons above 5 GeV and calculated mean magnetic field data shows that the observed spectral index of the radio continuum in the Galaxy is in conflict with some of the cosmic-ray electron measurements. It is found that the absolute intensities of cosmic-ray electrons measured by some of the experimenters are so low that they cannot be reconciled either with the interstellar magnetic field limits or with the extent of the galactic disk toward the anticenter.

Badhwar, G. D.↗
DOE OSTI2018

SLAC Microresonator Radio Frequency (SMuRF) Electronics for Read Out of Frequency-Division-Multiplexed Cryogenic Sensors

Large arrays of cryogenic sensors for various imaging applications ranging across x-ray, gamma-ray, cosmic microwave background, mm/sub-mm, as well as particle detection increasingly rely on superconducting microresonators for high multiplexing factors. These microresonators take the form of microwave SQUIDs that couple to transition-edge sensors or microwave kinetic inductance detectors. In principle, such arrays can be read out with vastly scalable software-defined radio using suitable FPGAs, ADCs and DACs. In this work, we share plans and show initial results for SLAC Microresonator Radio Frequency (SMuRF) electronics, a next-generation control and readout system for superconducting microresonators. SMuRF electronics are unique in their implementation of specialized algorithms for closed-loop tone tracking, which consists of fast feedback and feedforward to each resonator’s excitation parameters based on transmission measurements. Closed-loop tone tracking enables improved system linearity, a significant increase in sensor count per readout line, and the possibility of overcoupled resonator designs for enhanced dynamic range. Low-bandwidth prototype electronics were used to demonstrate closed-loop tone tracking on twelve 300-kHz-wide microwave SQUID resonators, spaced at ~ 6 MHz with center frequencies ~ 5–6 GHz. We achieve multi-kHz tracking bandwidth and demonstrate that the noise floor of the electronics is subdominant to the noise intrinsic in the multiplexer.

47 OTHER INSTRUMENTATION↗
DOE OSTI2019

Part 1: Detailed Electromagnetic Design of an Integrated and Compact 1.3 GHZ Superconducting Radio Frequency (SRF) Electron

There exists a need for compact, reliable, high-power electron sources for applications including those in water treatment, basic science, defense, and security. There also exists a need for compact electron-beam based light and power sources of various power levels and at different frequencies (mm-wave to gamma rays) for applications also in the fields of basic science, industry, and defense and security. Today’s examples of high-average-power electron sources are neither very compact nor highly efficient. The same may be said for many of the electron-beam based light sources operated worldwide for myriad of applications. Recent breakthroughs in superconducting (SC) materials technology, radio-frequency (RF) power systems, specialized cathodes, and RF cavity designs offer ways to overcome the above-mentioned shortcomings. In this report, all these new features are integrated in a comprehensive design into one promising concept for a compact superconducting RF (SRF) high-average power electron linear accelerator. This design is capable of 5-50 kW average electron beam power and continuous wave operation with the corresponding electron beam energy up to 10 MeV.

43 PARTICLE ACCELERATORS↗
NASA NTRS1981

Energetic electrons, Type III radio bursts, and impulsive solar flare X-rays

Observations of impulsive hard X-ray and type III radio bursts made during the maximum of the last solar activity cycle are analyzed. Spectral measurements of 10-68 keV X-rays were made with the University of California (Berkeley) experiment aboard the OGO 5 satellite. About 20% of impulsive hard X-ray bursts are correlated with type III radio bursts, whereas only about 3% of the reported type III radio bursts are correlated with impulsive X-ray bursts. The location of the associated H gamma flare on the solar disk has little effect on the X-ray-type III burst correlation. The magnitude of the X-ray-type III burst correlation increases systematically with an increase in the intensity and starting frequency of the radio burst, the peak energy and hardness of the X-ray burst, and the peak nonthermal emission measure and spectral hardness of the electron spectrum not less than 20 keV inside the X-ray source. Observations are consistent with the electron populations responsible for both the X-ray and type III emissions accelerated in a single acceleration process; they also suggest a flare model where the primary instability causing electron acceleration during the impulsive phase occurs in the corona.

Kane, S. R.↗
NASA NTRS1987

The speeds of electrons that excite solar radio bursts of type III

Evidence is presented that solar type III radio bursts at kilometric wavelengths are excited by electrons with average speeds of 0.14 c; i.e., in good agreement with in situ measurements by Lin et al. (1981; 1986), but considerably lower than the generally accepted values of 0.3 to 0.5 c. A set of 28 bursts for which electrons and/or plasma waves were observed at ISEE-3 is examined, and it is found that the initial parts of all bursts were due to plasma radiation at the fundamental, and that the fastest electrons that produce radio emission range from 0.25 c down to 0.07 c (average 0.14 c). The slower electrons, those that produce fundamental radiation at approximately the time of burst peak, have an average speed of 0.06 c and a range from about 0.10 c down to 0.03 c.There is no evidence in the data for a systematic increase or decrease of exciting electron speed with distance from the sun.

Dulk, G. A.↗
NASA NTRS1980

Radio emission, cosmic ray electrons, and the production of gamma-rays in the Galaxy

The paper examines the traditional derivation of the interstellar electron spectrum using the galactic nonthermal radio spectrum and new radio data. The radio spectrum derived in the polar directions is now used as a base for this derivation instead of the anticenter spectrum. The exponent is determined for the interstellar electron spectrum between 70 and 1200 MeV, and radio maps are used to predict the gamma-ray fluxes produced by the bremsstrahlung process expected from these electrons. The differences in the predicted and observed gamma-ray intensities in the galactic plane are small, but in the polar direction the predicted gamma-ray flux using radio data is six times larger than that actually observed.

Webber, W. R.↗
NASA NTRS1978

Plasma density mapping in the solar wind through use of VHF radio to measure electron content

How the electron content between the Solar probe and the earth can be observed with a minimum of equipment and give a quantitative rationale for the use of a signal near 400 MHz to supplement the telecommunications signal is described. The emphasis is on the method of making content observations and on their value. While far from the Sun, the electron content is so low that the S-X dual-frequency system is insufficiently sensitive and a UHF system is optimum. As the probe approaches the Sun, the UHF may be disrupted by scintillation and the variations of the telecommunications signal must be used for the content measurement. By operating the suggested system in different modes as the solar distance changes, operation during the entire mission is possible.

Croft, T. A.↗
NASA NTRS2009

Non-ambipolar radio-frequency plasma electron source and systems and methods for generating electron beams

An electron generating device extracts electrons, through an electron sheath, from plasma produced using RF fields. The electron sheath is located near a grounded ring at one end of a negatively biased conducting surface, which is normally a cylinder. Extracted electrons pass through the grounded ring in the presence of a steady state axial magnetic field. Sufficiently large magnetic fields and/or RF power into the plasma allow for helicon plasma generation. The ion loss area is sufficiently large compared to the electron loss area to allow for total non-ambipolar extraction of all electrons leaving the plasma. Voids in the negatively-biased conducting surface allow the time-varying magnetic fields provided by the antenna to inductively couple to the plasma within the conducting surface. The conducting surface acts as a Faraday shield, which reduces any time-varying electric fields from entering the conductive surface, i.e. blocks capacitive coupling between the antenna and the plasma.

Hershkowitz, Noah↗
NASA NTRS2011

Non-ambipolar radio-frequency plasma electron source and systems and methods for generating electron beams

An electron generating device extracts electrons, through an electron sheath, from plasma produced using RF fields. The electron sheath is located near a grounded ring at one end of a negatively biased conducting surface, which is normally a cylinder. Extracted electrons pass through the grounded ring in the presence of a steady state axial magnetic field. Sufficiently large magnetic fields and/or RF power into the plasma allow for helicon plasma generation. The ion loss area is sufficiently large compared to the electron loss area to allow for total non-ambipolar extraction of all electrons leaving the plasma. Voids in the negatively-biased conducting surface allow the time-varying magnetic fields provided by the antenna to inductively couple to the plasma within the conducting surface. The conducting surface acts as a Faraday shield, which reduces any time-varying electric fields from entering the conductive surface, i.e. blocks capacitive coupling between the antenna and the plasma.

Hershkowitz, Noah↗