Can Soft X-Rays Be Used as a Proxy for Total Energy Injected by a Flare into the Interplanetary Medium?

1994 ◽  
Vol 144 ◽  
pp. 267-270 ◽  
Author(s):  
Z. K. Smith ◽  
M. Dryer ◽  
M. Armstrong
Keyword(s):  
Numerical Model ◽  
Total Energy ◽  
Interplanetary Medium ◽  
Energy Estimates ◽  
X Rays ◽  
Interplanetary Shocks ◽  
Arrival Times ◽  
X Ray ◽  
Ex Post ◽  
Ex Post Facto

AbstractSolar flares are a source of impulsive energy releases on the Sun that can inject energy into the interplanetary medium. Some of these energy injections drive interplanetary shocks that can, in turn cause disturbances in Earth’s environment. In an attempt to quantify these energy releases using readily available observational data, we explore the possibility of using, as a proxy, the solar flare signatures observed in soft X-ray data. Our motivation has been prompted by the real-time operational requirements of NOAA and U. S. Air Force to provide estimates of arrival times and strengths of shocks that impact Earth’s magnetosphere. The luxury of extensive,ex post factostudies of flare total energy outputs is not possible in an operational context. This study is restricted to flares associated with shocks seen in the corona as metric type II radio bursts. Using GOES data, the energy released in the 1-8Å X-ray wavelength band is computed and then compared to the estimates made from a numerical model based on two-dimensional, time-dependent MHD modeling of flare-initiated interplanetary shocks. We find that the proxy energy estimates computed from the GOES data provideno advantageover the estimates made using the MHD-based numerical model.

scholarly journals Real-time forecasting of ICME shock arrivals at L1 during the "April Fool’s Day" epoch: 28 March – 21 April 2001

2002 ◽  
Vol 20 (7) ◽  
pp. 937-945 ◽  
Author(s):  
W. Sun ◽  
M. Dryer ◽  
C. D. Fry ◽  
C. S. Deehr ◽  
Z. Smith ◽  
...  
Keyword(s):  
Real Time ◽  
Radio Burst ◽  
Type Ii ◽  
Interplanetary Shocks ◽  
Arrival Times ◽  
Interplanetary Coronal Mass Ejection ◽  
Coronal Shock ◽  
Ex Post ◽  
Interplanetary Physics ◽  
Ex Post Facto

Abstract. The Sun was extremely active during the "April Fool’s Day" epoch of 2001. We chose this period between a solar flare on 28 March 2001 to a final shock arrival at Earth on 21 April 2001. The activity consisted of two presumed helmet-streamer blowouts, seven M-class flares, and nine X-class flares, the last of which was behind the west limb. We have been experimenting since February 1997 with real-time, end-to-end forecasting of interplanetary coronal mass ejection (ICME) shock arrival times. Since August 1998, these forecasts have been distributed in real-time by e-mail to a list of interested scientists and operational USAF and NOAA forecasters. They are made using three different solar wind models. We describe here the solar events observed during the April Fool’s 2001 epoch, along with the predicted and actual shock arrival times, and the ex post facto correction to the real-time coronal shock speed observations. It appears that the initial estimates of coronal shock speeds from Type II radio burst observations and coronal mass ejections were too high by as much as 30%. We conclude that a 3-dimensional coronal density model should be developed for application to observations of solar flares and their Type II radio burst observations.Key words. Interplanetary physics (flare and stream dynamics; interplanetary shocks) – Magnetosheric physics (storms and substorms)

On Proton and Electron Acceleration by Shock Waves during Large Solar Flares

1978 ◽  
Vol 3 (3) ◽  
pp. 236-238
Author(s):  
V. M. Gubchenko ◽  
V. V. Zaitsev
Keyword(s):  
Shock Waves ◽  
Total Energy ◽  
Satisfactory Agreement ◽  
Solar Flares ◽  
Interplanetary Medium ◽  
Thermal Processes ◽  
Proton Acceleration ◽  
X Ray ◽  
Target Model ◽  
Γ Ray

Lin and Hudson (1976) have recently analysed non-thermal processes in proton flares, using observations of a series of major events in August 1972. They concluded that the 10–100 keV electrons accelerated during the flash phase account for the bulk of the total energy of a large proton flare (about 1032 – 1033 ergs); that most protons are accelerated later than the 10 — 100 keV electrons; and that most energetic protons escape to the interplanetary medium. Their conclusions with regard to proton acceleration are supported firstly by the delay of the maximum of γ-ray emission by 3-5 minutes after the maximum of X-ray emission, and secondly by the satisfactory agreement between the 7-ray spectrum and the thin-target model of emission. The energetic protons contain a very small fraction of the total flare energy (of the order of 10-5).

scholarly journals Simultaneous Observations of Large Enhancement In the Flux of PSR 0950+08 Over a 200 km Baseline at 103 MHz

1996 ◽  
Vol 160 ◽  
pp. 477-478
Author(s):  
A.D. Bobra ◽  
Harish Chandra ◽  
Hari Om Vats ◽  
P. Janardhan ◽  
G.D. Vyas ◽  
...  
Keyword(s):  
Solar Wind ◽  
Interplanetary Medium ◽  
Temporal Variations ◽  
X Rays ◽  
Physical Research Laboratory ◽  
X Ray ◽  
The Earth ◽  
Wind Velocities ◽  
Electro Magnetic ◽  
Galactic Radio

Interplanetary Scintillation (IPS) is a diffraction phenomenon in which coherent electro-magnetic radiation, from a distant radio source, passes through the solar wind, which is a turbulent refracting medium, and suffers scattering. This results in random temporal variations of the signal intensity (scintillation) at the Earth. IPS observations to monitor the interplanetary medium (IPM), to measure solar wind velocities in the directions of a number of compact extra-galactic radio sources and to estimate the angular diameters of their compact components have been carried out for many years at 103 MHz using the IPS facility (Alurkar et al. 1989) of the Physical Research Laboratory (PRL), Ahmedabad, India. Over a period of approximately 10 years of such observations, it has been seen that PSR 0950+08 has always remained well within the noise level. We observed a sudden enhancement in its flux (Deshpande et al. 1994) on 29 July, 1992. The ionospheric observations which are being carried out on a regular basis at PRL using an ionosonde also recorded a steep increase in the absorption index Fmin, which is an indicator of the excess ionization produced due to X-rays. During this period, the Sun was exceptionally quiet, thereby raising the question about the origin of the X-ray flux responsible for the observed steep rise in Fminduring the transit of PSR 0950+08.

scholarly journals On the ionization of light gases by X-rays. II.—The ionization of hydrogen by recoil electrons

1933 ◽  
Vol 141 (845) ◽  
pp. 686-696 ◽  
Keyword(s):  
Total Energy ◽  
Wave Length ◽  
Practical Importance ◽  
Incident Beam ◽  
Direct Methods ◽  
X Rays ◽  
Recoil Electron ◽  
X Ray ◽  
Experimental Errors

In Part I, p. 669, a technique has been described for determining the ratio of the ionization in a light gas (hydrogen or helium) to that in air when ionized by the same X-ray beam, homogeneous rays of medium wave-length and soft heterogeneous rays being available for the measurement. The ionization ratio can be converted into the ratio of the energies absorbed by the two gases by making use of the known value of the ratio of the energies required to form a pair of ions in the two gases; and since the ionization in air is due almost entirely to photoelectrons and the absorption coefficient is known, the energy in the incident beam can be obtained from the energy absorbed by air; thus the energy absorbed by the light gas can be correlated with the energy in the incident beam. The radiation of medium wave-length (about ½ A.) ionizes the light gas chiefly through the agency of recoil electrons, so that after applying a correction (obtained from the soft ray ratio) for the ionization due to photoelectrons, the fraction of the energy in the incident beam converted into recoil electron energy by the gas may be obtained, and compared with the predictions of the quantum theory of recoil scattering. In this paper the comparison is carried out with measurements on hydrogen, and for convenience it will be made between the experimental and calculated values of the ionization ratios. Excluding the early work of Shearer already mentioned in I no experimental determination of the total energy associated with recoil electrons has hitherto been made by any method as direct as the present one, though less direct methods have been employed. In general, however, the experimental technique was open to criticism, and the interpretation of the measurements uncertain, so that it is not surprising that the results were inconsistent either with one another or with theory. It is also possible to calculate the total energy associated with recoil electrons from other experimental facts concerning recoil scattering, but the experimental errors involved combine to make the final result very unreliable. The energy associated with recoil electrons is, however, not only of theoretical interest but also of great practical importance, since all effects arising from scattering, in the scattering substance itself, are due to recoil electron emission.

An Approach to Sub-Pixel Spatial Resolution in Room Temperature X-Ray Detector Arrays with Good Energy Resolution

1997 ◽  
Vol 487 ◽  
Author(s):  
W. K. Warburton
Keyword(s):  
Spatial Resolution ◽  
Energy Resolution ◽  
Hole Transport ◽  
Energy Estimates ◽  
Weighted Sums ◽  
X Rays ◽  
Simple Analysis ◽  
Detector Arrays ◽  
X Ray ◽  
Good Energy

AbstractIn this paper we examine a recently proposed concept for obtaining sub-pixel spatial resolution in compound semiconductors where hole transport properties are relatively poor. [1] This approach uses weighted sums and differences of local pixel signals to extract both accurate x-ray energy estimates and interpolate location at the sub-pixel level. A simple analysis, including noise estimates, suggests the possibility of obtaining locations at the 50–100 micron level using 1–2 mm wide stripe electrodes while obtaining 1–2% energy resolution for x-rays up to 100 keV. Following this examination, we will present the most recent experimental results from our program to develop electronics to implement this scheme.

scholarly journals The observation of 10–50 KeV solar flare X-rays by the OGO satellites and their correlation with solar radio and energetic particle emission

1968 ◽  
Vol 35 ◽  
pp. 490-509
Author(s):  
R. L. Arnoldy ◽  
S. R. Kane ◽  
J. R. Winckler
Keyword(s):  
Magnetic Field ◽  
Solar Flare ◽  
Radio Emission ◽  
Total Energy ◽  
Total Duration ◽  
Microwave Emission ◽  
X Rays ◽  
Ionization Chambers ◽  
X Ray ◽  
Peak Intensity

More than 70 cases have been observed of energetic solar flare X-ray bursts by large ionization chambers on the OGO satellites in space. The ionization chambers have an energy range between 10 and 50 KeV for X-rays and are also sensitive to solar protons and electrons. A study has been made of the X-ray microwave relationship, and it is found that the total energy released in the form of X-rays between 10 and 50 KeV is approximately proportional to the peak or total energy simultaneously released in the form of microwave emission. For a given burst the rise time, decay time and total duration are similar for the 10–50 KeV X-rays and the 3 to 10 cm radio emission. Roughly exponential decay phases are observed for both emissions with time constants between 1 and 10 min. All 3 or 10 cm radio bursts with peak intensity greater than 80 solar flux units are accompanied by an X-ray burst greater than 3 × 10−7 ergs cm−2 sec−1 peak intensity. The probability of detecting such X-ray events is low unless the radio spectrum extends into the centimetric range of wavelengths. The best correlation between cm-λ and energetic X-rays is observed for the first event in a flare. Subsequent structure and second bursts may not correspond even when the radio emission is rich in the microwave component. The mechanism for the energetic X-rays is shown to be bremsstrahlung probably of fast electrons on a cooler plasma. If the radio emission is assumed to be synchrotron radiation then a relationship is developed between density and magnetic field which meets the observed quantitative results. One finds, on the average, that 5 × 10−54 joules m−2 (CPS)−1 of microwave energy at the Earth are required per electron at the Sun to provide the radio emission for the various events.A strong correlation between interplanetary solar flare electrons observed by satellite and X-ray bursts is shown to exist. This correlation is weak for solar proton events. One may infer a strong propagation asymmetry for solar flare electrons along the spiral interplanetary magnetic field.

Spectral Analysis of X-Rays from Laser-Induced Plasmas†

1974 ◽  
Vol 18 ◽  
pp. 159-168 ◽  
Author(s):  
J. F. Cuderman ◽  
K. M. Glibert
Keyword(s):  
Spectral Analysis ◽  
Total Energy ◽  
Spectral Range ◽  
Laser Energy ◽  
Laser System ◽  
X Rays ◽  
Laser Interaction ◽  
Tetrahedral Geometry ◽  
X Ray ◽  
Beam Laser

AbstractLaser interaction experiments have been conducted on Sandia Laboratories' four-beam laser system. In these experiments, pulses of 1.06 μm light of up to 50 J each were focused in a tetrahedral geometry onto CD2 microspheres. A 22-channel x-ray spectrometer which utilises silicon diodes with appropriate K-edge prefilters was used for x-ray measurements. Typically, bremsstrahlung-recombination spectra were observed in the photon regime below about 5 keV. The electron temperatures for this part of the spectrum ranged from a few hundred eV to 1 keV with up to 15 percent of the total laser energy converted to x-rays. Less than one percent of the total energy emitted as x-rays appeared in the spectral range above 5 keV.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

Chemical Species Identification in an SEM by Changes in Emitted X-Ray Energies

1974 ◽  
Vol 32 ◽  
pp. 570-571
Author(s):  
R. H. Duff
Keyword(s):  
Species Identification ◽  
Valence Electron ◽  
Chemical Species ◽  
X Rays ◽  
Chemical Bonds ◽  
Small Shift ◽  
X Ray ◽  
Electron Transitions ◽  
Peak Energy ◽  
Chemical Combination

A material irradiated with electrons emits x-rays having energies characteristic of the elements present. Chemical combination between elements results in a small shift of the peak energies of these characteristic x-rays because chemical bonds between different elements have different energies. The energy differences of the characteristic x-rays resulting from valence electron transitions can be used to identify the chemical species present and to obtain information about the chemical bond itself. Although these peak-energy shifts have been well known for a number of years, their use for chemical-species identification in small volumes of material was not realized until the development of the electron microprobe.

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