[1] A sub-Alfve´nic jet in the tailward outflow region near the separatrix of the magnetic reconnection is observed by Geotail on 9 February 1995. Several dozens of electrostatic solitary waves/pulses (ESWs) are observed, respectively, on the current sheet-side and the lobe-side of the separatrix. The ESWs on the current sheet-side are of type-B with direction outward (toward to the tailward) while on the lobe-side they are of type-A directed to X-line. The amplitude of ESWs on the current sheet-side is about 6 times more than those on the lobe-side, suggesting that energies flowing outward from the reconnection X-line are much larger than those flowing inward. Moreover, observations show, that electron beams associated with ESWs, which are parallel to the ambient magnetic field, are much stronger on the current sheet-side than on the lobe-side of the separatrix. Furthermore, the direction of the electron beam on the lobe-side of the separatrix is mainly antiparallel to the ambient magnetic field and it is mainly parallel on the current sheet-side. Both are consistent with the propagation of ESWs which is in agreement with the generation mechanism of ESWs, which is suggested to be related to electron beams. These results are helpful for solving the issue of ESWs' generation mechanism associated with magnetic reconnection. It also provides an important clue for understanding the fast energy release during the magnetic reconnection process.
[1] In this paper, we report the observations and statistical characteristics of tripolar electrostatic solitary waves (ESWs) along the plasma sheet boundary layer near the magnetic reconnection X line in the near-Earth magnetotail. Within reconnection diffusion region, the tripolar ESWs are ample and are continuously observed during one burst interval (8.75 s) of the Geotail/WaveForm Capture in the neutral plasma sheet where b > 1 on 10:20 UT, 2 February 1996. The tripolar ESW is suggested to be one kind of steady-going solitary structure. More than 200 waveforms with clear tripolar characteristics are differentiated for statistical analysis, and result shows that (1) their amplitude is within 100->500 mV/m, with an average amplitude of about 254 mV/m; (2) the pulse width of the tripolar ESWs is 0.5-1.0 ms, with an average value of about 0.75 ms; (3) it is asymmetrical in both the amplitude and pulse width of the tripolar ESWs: most part of the tripolar ESWs (about 76.5%) are asymmetrical in the amplitude of one hump and the other one, and more than 75% (about 177 amount the 236 waveforms) of the tripolar ESWs are asymmetrical in the time duration of the two humps in the waveform; (4) most of the tripolar ESWs are with the potential humps of 10-60 mV, small ratio of them with potential humps larger than 100 mV. The tripolar ESWs with net potential drop of about 10-50 mV can be interpreted as "weak" double layers. The possible generation mechanism of tripolar ESWs and their role in reconnection are discussed by studying the particle distribution during which the tripolar ESWs are continuously observed. The observation of tripolar ESWs presents evidence of complex structure of electron holes within the reconnection diffusion region and is helpful to the understanding of the energy release process of reconnection.
Single point diamond turning (SPDT) is highly controllable and versatile in producing axially symmetric forms, non-axially-symmetric forms, microstructured surfaces, and free forms. However, the fine SPDT marks left in the surface limit its performance, and they are difficult to reduce or eliminate. It is unpractical for traditional methods to remove the fine marks without destroying their forms, especially for the aspheres and free forms. This paper introduces abrasive jet polishing (AJP) for the posttreatment of diamond-turned surfaces to remove the periodic microstructures. Samples of diamond-turned electroless nickel plated plano mirror were used in the experiments. One sample with an original surface roughness of more than 400 nm decreased to 4 nm after two iterations abrasive jet polishing; the surface roughness of another sample went from 3.7 nm to 1.4 nm after polishing. The periodic signatures on both of the samples were removed entirely after polishing. Contrastive experimental research was carried out on electroless nickel mirror with magnetorheological finishing, computer controlled optical surfacing, and AJP. The experimental results indicate that AJP is more appropriate in removing the periodic SPDT marks. Also, a figure maintaining experiment was carried out with the AJP process; the uniform polishing process shows that the AJP process can remove the periodic turning marks without destroying the original form.
[1] Several cases of short-time durational large-amplitude three-dimensional (3-D) electrostatic solitary waves (ESWs) are observed within the transition layer of the terrestrial bow shock by THEMIS/E. Their pulse width is small (0.8-2 ms), but the amplitude is large (greater than 100 mV/m), suggesting a very strong potential drop. Two character angles (y 1 and y 2 ) are defined to describe the 3-D characteristics of the ESWs, and it returns results as 76 > y 1 > 27 and 70 > y 2 > 20 , suggesting that the electron potential holes are mainly in 3-D ellipsoid sphereshaped structure, including "pancake-shaped" structure and "sphere-shaped" structure. None of the theories commonly used to describe ESWs adequately address these pancakeshaped and sphere-shaped three-dimensional structures observed in the terrestrial bow shock, where o ce < < o pe in a weak magnetized plasma. The observation of large three-dimensional ESWs with different spatial structures during small time interval suggests anisotropic distribution of electric potentials and presents evidence of complex wave fluctuation within the bow shock. Citation: Li, S. Y., S. F. Zhang, H. Cai, X. H. Deng, X. Q. Chen, M. Zhou, and H. B. Yang (2013), Large three-dimensional ellipsoid sphereshaped structure of electrostatic solitary waves in the terrestrial bow shock under condition of Ω ce /o pe < < 1, Geophys. Res. Lett., 40,[3356][3357][3358][3359][3360][3361]
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