A compact design for velocity-map imaging of energetic electrons and ions

Recent progress and future prospects in diagnostics of energetic electrons and ions in the flares are reviewed, together with the roles they play in the flare as a whole. Most of the discussion centres on hard X-ray and gamma-ray and thermal plasma emission data, rather than on radio sources. Since Solar Maximum Mission and Hinotori there has been major progress in all areas of flare electron diagnostics. Electron spectra are now recoverable with some precision, electrons with energies above 10 MeV are known to be highly anisotropic, and indications are available of the spatial distribution of electrons at 20 keV. Timescales of electron acceleration are now known to be shorter than 0.1 s. Energetic electrons are believed to carry much of the flare power. Ion diagnostics are more limited. For greater than 1 MeV ions the flux, spectrum and acceleration timescale are now quite well known. Low energy ions are hard to diagnose but have been invoked as a flare heating mechanism alternative to electron beams. The problems with beam heating models are discussed with special attention to the problems of the low energy proton model and its only direct diagnostic, Hα impact polarization. Finally, theoretical problems associated with return currents and with accelerator requirements are discussed and attention is drawn to the possible importance of entropy as well as energy considerations.

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Energetic electrons and ions in the magnetosheath at low and medium latitudes: Prognoz 10 data

Journal of Geophysical Research Atmospheres ◽

10.1029/92ja01134 ◽

1992 ◽

Vol 97 (A10) ◽

pp. 14849 ◽

Cited By ~ 17

Author(s):

K. Kudela ◽

D. G. Sibeck ◽

M. Slivka ◽

S. Fischer ◽

V. N. Lutsenko ◽

...

Keyword(s):

Energetic Electrons ◽

Electrons And Ions

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Simultaneous observation of upward moving field-aligned energetic electrons and ions on auroral zone field lines

Journal of Geophysical Research Atmospheres ◽

10.1029/ja093ia09p09765 ◽

1988 ◽

Vol 93 (A9) ◽

pp. 9765 ◽

Cited By ~ 106

Author(s):

B. Hultqvist ◽

R. Lundin ◽

K. Stasiewicz ◽

L. Block ◽

P.-A. Lindqvist ◽

...

Keyword(s):

Auroral Zone ◽

Simultaneous Observation ◽

Energetic Electrons ◽

Electrons And Ions ◽

Field Lines ◽

Upward Moving ◽

Zone Field

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In situ irradiation effects studies in medium- and high-voltage TEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100137549 ◽

1995 ◽

Vol 53 ◽

pp. 234-235

Author(s):

Charles W. Allen

Keyword(s):

Cross Section ◽

Particle Flux ◽

Threshold Value ◽

High Energy ◽

Irradiation Damage ◽

Defect Complexes ◽

Lattice Position ◽

Electrons And Ions ◽

The Masses

With respect to structural consequences within a material, energetic electrons, above a threshold value of energy characteristic of a particular material, produce vacancy-interstial pairs (Frenkel pairs) by displacement of individual atoms, as illustrated for several materials in Table 1. Ion projectiles produce cascades of Frenkel pairs. Such displacement cascades result from high energy primary knock-on atoms which produce many secondary defects. These defects rearrange to form a variety of defect complexes on the time scale of tens of picoseconds following the primary displacement. A convenient measure of the extent of irradiation damage, both for electrons and ions, is the number of displacements per atom (dpa). 1 dpa means, on average, each atom in the irradiated region of material has been displaced once from its original lattice position. Displacement rate (dpa/s) is proportional to particle flux (cm-2s-1), the proportionality factor being the “displacement cross-section” σD (cm2). The cross-section σD depends mainly on the masses of target and projectile and on the kinetic energy of the projectile particle.

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