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Department Library

1996

Dawn K. Gifford (Honors Thesis, March 1996, Advisor: Douglas Jones )

Abstract

1995

Noe Yamaguchi (Honors Thesis, March 1995, Advisor: Douglas Jones )

Abstract

1993

Laralee Gordon Ireland (Masters Thesis, December 1993, Advisor: Douglas Jones )

Abstract

The earth’s magnetosphere is formed by a viscous interaction between the solar wind and the earth’s intrinsic magnetic field. Magnetic field lines are draped around the earth to form a magnetic tail which points anti-sunward. The international Sun Earth Explorer 3 (ISEE-3), launched in 198, performed two passes of the distant geotail from 180 to 245 R in 1983. Magnetometer data from these passes were used to study the nature of the distant tail lobes. A simple compute model of the tail using OMNI tape solar wind data and ISEE-3 trajectory data suggests that the windsock idea of a magnetic tail flapping with fluctuations in the solar wind flow is not consistent with the data obtained from ISEE-3. Another explanation besides the windsock effect is needed to explain why the tail lobe readings are found to be mainly short time duration events throughout the tail, especially in the middle of the regions considered to be solely tail lobe. Filamentation of the tail lobe is suggested as a viable alternative explanation. The filaments are scattered more or less uniformly throughout the tail and are on the average about 0.2 to 0.4 R in diameter. Possible causes such as broken symmetries in the tail by the presence of a B component, plasma instabilities, and turbulence are discussed. The impact of filamentation is significant and would result in a new insight into the dynamics of the tail useful to all those who study the tail and in particular those who seek to model the tail. Also, there would exist a possible need for reclassification of some of the data previously identified as plasma sheet or plasma sheet boundary layer that is found in the middle of the tail lobe as inter-filament plasma. While these filaments are not flux tubes similar to those related to plasmoids, understanding of lobe filaments will aid in the understanding of flux tubes.

1991

Stephen Richard McNeil (Masters Thesis, December 1991, Advisor: Douglas Jones )

Abstract

A study has been undertaken that shows the solar wind ram pressure exerts more control over magnetotail lobe structure than the IMF Bz polarity. The results of this study also suggest that there is a near-earth neutral line in the -20 Re GSMX range that is present on the average, and not a transient phenomenon. An AE index study has been done to show its correlation to the IMF Bz polarity. Then the AE index was compared to the geotail lobe field data. Another comparison was done between 5-minute IMP-8 lobe data and external solar wind and IMF data taken from the ISEE-3 satellite.

1989

Michael Todd Johnson (PhD Dissertation, April 1989, Advisor: Douglas Jones )

Abstract

A disturbance in the plasma flow behind Titan was detected by Pioneer 11. A year later Voyager 1 passed directly behind Titan. Voyager obtained data on an extended atmosphere of Titan which is responsible for the disturbance. A computer simulation that utilizes the parameters of the flow and the makeup of the upper atmosphere and ionosphere, in combination with the laws of plasma dynamics, has been generated and is presented here. Using this simulation an analysis of the system has been executed for different positions of Titan in its orbit and as a function of time at each place. Different regions of the reaction are clearly depicted, including the flow upstream, a bow wave that apparently is not a shock and varies in intensity at different pints in the orbit, an ionosheath, and a low density region inside a stretched ionosphere. The electric field looks as if a conducting ring were placed in the tail. The results of this study could be used in the planning of the Cassini mission.

1988

Snehavadan Ema Macwan (Masters Thesis, December 1988, Advisor: Douglas Jones )

Abstract

Observations from magnetic field and plasma experiments on ISEE-3 are used to identify and to analyze 16 crossings of the distant magnetotail neutral sheet. Four methods of analyses have been employed to measure the extent of the magnetotail twisting which is found to be much greater than previously observed, or theoretically inferred twist. A twist of more than 90 degrees has frequently been observed on both open and closed magnetic field lines. In addition, the location of the magnetic neutral line of the magnetic field lines has been found to move over the distance interval of 115 to 220 Earth radii. Some features of these results suggest that a modification of the present solar wind-geomagnetic field interaction model may be needed.

1987

Gordon Ray Wilson (PhD Dissertation, December 1987, Advisor: Douglas Jones )

Abstract

The rings of Saturn, being immersed in a plasma and exposed to ultraviolet radiation from the sun, will be electrically charged. The charging of the rings is studied in this work through the numerical solution of the Boltzmann equation. The work includes the effect of plasma loss and photoelectron production within the rings. Several aspects of the rings’ structure (thickness, average particle size, cross sectional profile, and optical depth) can be varied to illustrate the effect of these parameters on the resulting charge. The solution for several cases at low plasma density (0.01 cm^-3) and high plasma density (100.0 cm^-3) are presented. The results presented have implications for several processes occurring in the rings. The amount of current carried by the rings may be an order of magnitude larger than the amount estimated by charging studies which use a flat plate description of the rings. If spokes form by the theory of Goertz and Morfill (1983), the rings must be very thin with tightly packed particles. The disruption and accretion of small dust grains within the rings may be greatly enhanced by the strong electric fields there. The charging processes considered here are probably not the source of the Saturn Electrostatic Discharge radio emissions although they may contribute to the lower frequency portion of the Saturn Kilometric Radiation emissions.

1983

Bryan G Peterson (PhD Dissertation, April 1983, Advisor: Douglas Jones )

Abstract

The time evolutions of several spectral lines of naturally occurring impurity atoms (carbon and oxygen) have been recorded for the plasma in the BYU Topolotron. The electron density has been measured using a laser interferometer. The measured time-dependence of the electron density has been used to infer the evolution of the electron temperature by vying the temperature versus time curve until the theoretical time development of the spectral line intensities matched those which had been experimentally determined. The theory used in determining the theoretical intensities is reviewed with emphasis on application to the Topolotron plasma. The basis of the electron density measurement is also reviewed. Data are presented which were taken in the C-mode of operation in which a tokamak-like configuration is achieved.

1976

Albert Johnson (Masters Thesis, December 1976, Advisor: Douglas Jones )

Abstract

An infrared emission-absorption system has been constructed to measure flame temperatures of gas combustion in a closed vessel. The system consists of a rapid-scanning spectrometer, radiation furnace, mechanical chopper, sphyerical combustion chamber and a high-speed analog to digital conversion system. The flame temperatures from four stoichiometric methane-air explosions were measured following the initial 40 millisecond induction period. The extrapolated temperatures into the 40 millisecond period were near the 2223 degree kelvin constant pressure value which is calculated. Temperatures measured at maximum pressure were within 50 degrees of the constant volume temperature which was calculated to be 2625 degrees kelvin.

1975

Robert Gordon George (PhD Dissertation, January 1975, Advisor: Douglas Jones )

Abstract

The sources of solar wind streams have been the object of intensive research for amny years, but the various ideas of where and hwo streams originate on the sun are still incomplete and contradictory. The present study is an attempt to find the solar wind sources by mathematically approximating the 9.1 cs brightness temperature which would be expected at the foot of spacecraft-measured solar wind streams and by then comparing it with actual radio brightness temperature measurements. Several significant results were found from an analysis of the correlation results. Most plasma emanating from the sun was found to come from high solar latitudes and to deviate significantly from the normally expected east-west path in the low corona. Magnetic channeling causes correlation studies to fail when the sun’s magnetic configuration is unstable. The travel time of the plasma from the sun’s 9.1 cm emission level to the earth is often more than a month.

1970

Don Morris Wrathall (PhD Dissertation, May 1970, Advisor: Douglas Jones )

Abstract

The disc brightness temperature of Venus as measured in the spring and fall of 1966 and again during 1967-68 at a number of discrete frequencies in a band centered near the 22.235 GHz H2O rotation-absorption line. The spring, 1966 results gave band average values of TB-disc = 580 ± 64o K (scatter only) and T1 = 241 ± 290o K, where T1 is the amplitude of the change in the TB-disc versus k curve. T1 was definitely positive near 22 GHz. Two theoretical models of an atmosphere composed of CO2. N2, H2O, and dust and allowing for the presence or absence of an absorbing cloud layer consistent with recent space probe data yielding TB-disc and phase effects consistent with the observations. Flux measurements of Tau-A were 415, 377, and 337 flux units at 21, 22.3, and 23GHz. Evidence was found for a “wet” earth’s stratosphere.

1969

Leroy Edison Sievers (PhD Dissertation, January 1969, Advisor: Douglas Jones )

Abstract

Interplanetary magnetic field data obtained from Mariners II, IV, and V during the first two months of each flight are studied to determine relationships between the interplanetary magnetic field direction and large scale geomagnetic activity. High geomagnetic activity is found to occur equally often with north pointing and south pointing fields. Considering data from all three flights, geomagnetic activity appears to be nearly independent of the north-south direction of the interplanetary field. This result implies that proposed mechanisms relating interplanetary parameters to geomagnetic activity which depend on a southward point field are not correct. Cross correlation coefficients were computed between geomagnetic indices and interplanetary magnetic field variables in both a geomagnetic dipole coordinate system and a heliocentric equatorial system. The results indicated that no direction in the dipole system is directly related to the mechanism.

1966

Keith Henry Stirling (Masters Thesis, August 1966, Advisor: Douglas Jones )

Abstract

The successful flight of Mariner IV provided a long term monitor of the interplanetary magnetic field. The telemetered data associated with a 3 ½ month period in which the probe was in the near Earth region has been analyzed. On the 104 days, 60% had an average field pointing away from the Sun along the preferred spiral angle with a component directed below the ecliptic plane. The magnitude of the daily field ranged between 1.8 and 11.0 γ (1 γ = 10-5 gauss). The four sector polarity pattern as indicated by Imp-l measurements was also observed by the Mariner IV. Moreover, geomagnetic storms and Most Disturbed Days are generally associated with the spiraling-in (directed towards the Sun) sectors. In early March there existed approximately a one day time lag between geomagnetic disturbances and a corresponding disturbance at the probe-thus giving credence to the disturbance propagating at a finite, non-relativistic velocity. Snyder, et al.’s empirical expression for plasma velocity provided an approximate means to determine “time lag.” Cross correlation of the vector interplanetary field with the geomagnetic disturbance indice, Ap, has yielded a correlation coefficient of 0.62 ± .14 for the overall period and 0.86 ± .11 for the most active period during the Earth-Sun-probe angle was also a minimum. A least square fit to the data yielded the relation B (γ) = 0.18 (±0.02) Ap + 3.37 (0.19) for the field strength in the heliocentric range 1-1.2 AU. The analysis further inferred that the variations in the interplanetary field components as related to geomagnetic disturbances are similar regardless of whether the solar storm is transient or recurrent.