The collective gyration of a heavy ion cloud in a magnetized plasma

In both the ionospheric barium injection experiments CRIT 1 and CRIT 2, a long duration oscillation was seen with a frequency close to the gyro frequency of barium and a time duration of about one second. A model for the phenomena which was proposed for the CRIT 1 experiment is compared to the results from CRIT 2 which made a much more complete set of measurements. The model follows the motion of a low Beta ion cloud through a larger ambient plasma. The internal field of the model is close to antiparallel to the injection direction v sub i but slightly tilted towards the self polarization direction E sub p = -V sub i by B. As the ions move across the magnetic field, the space charge is continuously neutralized by magnetic field aligned electron currents from the ambient ionosphere, drawn by the divergence in the perpendicular electric field. These currents give a perturbation of the magnetic field related to the electric field perturbation by Delta E/Delta B approximately equal to V sub A. The model predictions agree quite well with the observed vector directions, field strengths, and decay times of the electric and magnetic fields in CRIT 2. The possibility to extend the model to the active region, where the ions are produces in this type of self-ionizing injection experiments, is discussed

High latitude E-region irregularities: New results

Radar observations have shown that the phase velocity of small scale (a few meters and smaller) auroral two stream waves remains close to the ion acoustic speed. However, during periods of very large plasma drifts the electron temperature, and consequently, the ion acoustic speed in the auroral electrojet region is enhanced possibly by strongly driven two stream waves. Recent nonlinear theories can explain the large anomalous electron heating as well as the variation of the two stream phase velocity. However, the observations of plasma waves at angles larger than a few degrees from the perpendicular to the magnetic field remain unexplained. Radar interferometer measurements show that during very active periods strong echoes are often observed from highly localized and dynamic scattering regions. On these occasions, the two stream waves have phase velocities which can exceed 900 m/s, and the gradient drift waves have very broad spectra with mean phase velocities sometimes larger than 600 m/s. Furthermore, resonant (i.e., sharply peaked) auroral radar echoes, with Doppler shifts independent of the ambient cross field plasma drift are often present near the edges of auroral arcs. These waves have been associated with ion cyclotron waves driven by very large field aligned drifts in the upper E-region. This paper will review recent experimental results on the study of meter scale plasma waves in the auroral E-region, particularly during highly disturbed periods, and will also discuss the physical processes responsible for their generation and saturation

First VHF auroral radarinterferometer observations

The radar interferometer technique first used at the magnetic equator in Peru is also a very powerful means for studying auroral plasma instabilities. We present here the first results, obtained with a 49.92 MHz, 20-25 KW peak power pulsed radar located in Ithaca, NY (42.5° N, 76.4° W). Strong auroral echoes were obtained during several highly active periods. Phase differences between the signals received on the two antennas accurately determine the E-W position, within the scattering volume, of localized scattering centers, and changes in this phase determine the corresponding velocity. The signal Doppler shift describes radial (essentially N-S) motion. The data provide detailed information on the turbulent structure of the echoing region and show clearly that different features in the Doppler power spectrum often represent signals coming from different locations. If we assume that the radial and transverse phase velocities represent real drift velocities, we can determine full horizontal velocity vectors from the data and hence the horizontal electric field, usually with a time resolution of the order of 15-30s

The Collective Gyration of a Heavy Ion Cloud in a Magnetized Plasma

Invited talk at COASPAR Plenary Meeting 1990.To be published in Advances in Space Research.QC 20120530</p

Re-presentation and emerging authority of the Jeremiah traditions in Second Temple Judaism

The Prophet Jeremiah was a figure of fascination in ancient Judaism, extending well back into the Persian period. Copies of six MSS from the Qwnran scrolls now designated the Apocryphon of Jeremiah C (4Q385a, 4Q387, 4Q388a, 4Q389, 4Q390, 4Q387a)-as well as two other Jeremiah 'Apocrypha' (4Q383, 4Qpap384)-attest to his prevailing interest for the Qumran sectarians. However, because of the supposed paucity of exegetical treatments from the Book of Jeremiah at Qumran, and .because of the small number and poor condition of scriptural Jeremiah texts, commentators have tended to dismiss his impact in the Dead Sea Scrolls. Only fairly recently have studies revealed a thematic importance for the Prophet Jeremiah in the sectarian leadership ideal, but his overall siw.ificance and function have yet to be factored in connection with the actual contents of=t;{pocryphon of Jeremiah C. . study is a close reading of the Apocryphon of Jeremiah C, but Within the broader realm of discussions pertaining to so-called 'rewritten Bible,' the processes that guided Scripture transmission, and the impact of collective memory, pUblic personae and commemorated 'reputations' in Second Temple Jewish literature. The individual MSS of the Apocryphon are considered for how they are inter-related and for how they reflect a history of development that perhaps corresponds with the social world of its authors and collectors. The text is evaluated synchronically for how the Prophet Jeremiah is presented, and for how his character functioned as a leadership ideal and critique. The contents of the Apocryphon and the Jeremiah traditions are then evaluated within the Qwnran sectarian literature to expand and enhance the presence and impact of the Jeremiah figure and the Jeremiah Scriptures for the sectarian group. This discussion is situated in its historical milieu through a consideration of Jeremianic traditions that are extant elsewhere in Second Temple Judaism. The selection of texts is not exhaustive, but is focused on those that feature or reflect elements of Jeremiah's character as either a prophet, a priest, or a Mosaic leader. This study will then consider how these various re-presentations of the Jeremiah figure served as authorizing features, and how they are related to the transmission and use of Scripture, the transition of prophecy from an oral to a scribal medium, and how the employment of this single individual served to enforce a multiplicity of cultural and religious ideals. The Jeremianic traditions in Second Temple Judaism reveal a recognition and regard for Jeremiah's personae, which appear to have imbued individual texts and ideals with authority in their employment.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Auroral E-region plasma waves andelevated electron temperatures

We have observed 3-m auroral E region plasma waves with a high-resolution 50-MHz radar interferometer at Ithaca. During postmidnight periods of very strong magnetic activity at Ottawa (L = 3.5), the backscattered power and Doppler spectra vary rapidly with time and range and may have both mean Doppler shifts and half power widths in excess of 200 Hz (600 m/s). In addition, when the radar and magnetometer data imply that the current is approximately parallel to the radar line of sight, sharp spectral peaks corresponding to phase velocities approaching 1 km/s sometimes appear suddenly. These persist for at most several tens of seconds at any particular range and their amplitude seems to be more strongly dependent on the drift velocity than is the strength of the wide spectral component, which generally broadens substantially before the high-velocity peak appears. The shape of the peaks and their time evolution lead us to believe that they represent a true two-stream instability, implying an ion acoustic velocity in the medium of about 900 m/s in extreme cases, which, in turn, means an E region electron temperature of as much as 2000 K or more at latitudes as low as L = 3.5. This interpretation of the data is consistent with recent E region incoherent scatter measurements and helps to resolve some questions raised in connection with earlier coherent radar studies

Observations of auroral E region plasma waves and electron heating withEISCAT and a VHF radar interferometer

Two radars were used simultaneously to study naturally occurring electron heating events in the auroral E-region ionosphere. During a joint campaign in March 1986 the Cornell University Portable Radar Interferometer (CUPRI) was positioned to look perpendicular to the magnetic field to observe unstable plasma waves over Tromsø, Norway, while EISCAT measured the ambient conditions in the unstable region. On two nights EISCAT detected intense but short lived (\u3c 1 min) electron heating events during which the temperature suddenly increased by a factor of 2–4 at altitudes near 108 km and the electron densities were less than 7 × 104 cm−3. On the second of these nights CUPRI was operating and detected strong plasma waves with very large phase velocities at precisely the altitudes and times at which the heating was observed. The altitudes, as well as one component of the irregularity drift velocity, were determined by interferometric techniques. From the observations and our analysis, we conclude that the electron temperature increases were caused by plasma wave heating and not by either Joule heating or particle precipitation