The need for low propellant weight, high efficiency propulsion systems is a glaring need for various space missions. This thesis presents the thrust modeling of the Dense Plasma Focus plasma motion phases. It also contrasts some of the engineering tradeoffs between the existing coaxial plasma thrusters and the Dense Plasma Focus. Modeling the thrust generated by the DPF started with seeing how far the working models for the MPD would take the DPF. The effect of pulsed compared to quasi-steady state operation is computed. There is no known experimental data regarding thrust measurements for any DPF, so the thrust is analytically calculated using experimental data for the TAMU DPF. The calculated thrust is slightly higher than the thrust predicted by the models. The developed model shows that the force generated by the DPF will produce a thrust roughly three times the thrust for the MPD for similar input currents and electrode geometry. For the TAMUDPF to compete with the MPD as a thruster, it will need to be able to fire roughly 75 more times a second than the MPD.

The need for low propellant weight, high efficiency propulsion systems is a glaring need for various space missions. This thesis presents the thrust modeling of the Dense Plasma Focus plasma motion phases. It also contrasts some of the engineering tradeoffs between the existing coaxial plasma thrusters and the Dense Plasma Focus. Modeling the thrust generated by the DPF started with seeing how far the working models for the MPD would take the DPF. The effect of pulsed compared to quasi-steady state operation is computed. There is no known experimental data regarding thrust measurements for any DPF, so the thrust is analytically calculated using experimental data for the TAMU DPF. The calculated thrust is slightly higher than the thrust predicted by the models. The developed model shows that the force generated by the DPF will produce a thrust roughly three times the thrust for the MPD for similar input currents and electrode geometry. For the TAMUDPF to compete with the MPD as a thruster, it will need to be able to fire roughly 75 more times a second than the MPD.

No description available.

Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 66-67).

The X-ray emission from a plasma focus has been studied using time integrated and streak photography. The plasma focus, a small volume of very dense and hot plasma was created in a coaxial plasma gun driven by a fast current pulse of period T ~ 2 μsec which was produced by discharging a condensor bank of V = 12-15 kV, and C = 84 μf. Measurements have shown that a diffuse X-ray emitting plasma column is formed in the 'early' pinch stage, which extends a few centimeters in the axial direction, has expansion velocities of between 2-6 x 10⁷ cm/sec. and lasts for 30-60 nsec. In the following 10-30 nsec. X-ray emission occurs from small plasma regions which have little or no axial velocity. The distance between these "hot" spots are of the order of half a centimeter. These measurements and observations of the X-ray emitting regions are consistent with results obtained by Peacock and Mather. By comparing their results with those of this experiment it is concluded that the appearance of the isolated X-ray sources is associated with the m = 0 instability. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Doctor of Philosophy / Department of Mechanical and Nuclear Engineering / William L. Dunn / Dense Plasma Focus (DPF) devices are multi-radiation sources of X rays, neutrons (when working with deuterium), ions, and electrons in pulses typically of a few tens of nanoseconds. The Kansas State University device (KSU-DPF) was commissioned to be used as a radiation source with the Mechanical and Nuclear Engineering Department. The device is operated by a 12.5 µF capacitor which can be charged up to 40 kV storing an energy of 10 kJ. The static inductance and resistance of the device L[subscript]0 and r[subscript]0 were measured to be 91±2 nH and 13±3 mΩ. Experiments have shown that the KSU-DPF device produces 2.45 MeV neutrons with a neutron yield of ~2 × 10^7 and 1.05 × 10^7 n/shots in both axial and radial directions. Ions up to 130 keV were measured using a Faraday Cup. The measured hard X-ray spectrum shows an X-ray emission in the range from 20 to 120 keV with a peak at 50 keV while the average effective energy was estimated, using a step filter method, to be 59±3 keV. The KSU-DPF device was used as a pulsed hard X-ray source for material interrogation studies using the signature-based radiation-scanning (SBRS) technique. The SBRS technique uses template matching to differentiate targets that contain certain types of materials, such as chemical explosives or drugs, from those that do not. Experiments were performed with different materials in cans of three sizes. Nitrogen-rich fertilizers and ammonium nitrate were used as explosive surrogates. Experiments showed 100% sensitivity for all sizes of used samples while 50% specificity for 5 and 1- gallon and 28.57% for quart samples. Simulations using MCNP-5 gave results in good agreement with the experimental results. In the simulations, a larger number of materials, including real explosives were tested. To ensure the feasibility of using the DPF devices for this purpose a second device was simulated and the results were encouraging. Experimental and simulation results indicate that use of DPF devices with simple, room-temperature detectors may provide a way to perform rapid screening for threat materials, especially for places where large number of packages need to be investigated.

Doctor of Philosophy / Department of Mechanical and Nuclear Engineering / William L. Dunn / Dense plasma focus (DPF) devices are pulsed power devices capable of producing short-lived, hot and dense plasmas (~10[superscript]19 cm[superscript]-3) through a fast compression of plasma sheath. A DPF device provides intense bursts of electrons and ion beams, X-rays, and 2.5 MeV neutrons when operated with deuterium through the fusion reaction [superscript]2H(d,n)[superscript]3He. The Kansas State University DPF machine was designed and constructed in early 2010. The device was characterized to determine its performance as a neutron source. The device was shown to produce 5.0x10[superscript]7 neutrons/pulse using a tungsten-copper anode. Such machines have the advantages of being non-radioactive, movable, and producing short pulses (typically tens of nanoseconds), which allows rapid interrogation. The signature-based radiation-scanning (SBRS) method has been used to distinguish targets that contain explosives or explosive surrogates from targets that contain materials called “inert,” meaning they are not explosive-like. Different targets were placed in front of the DPF source at a distance of 45 cm. Four BC-418 plastic scintillators were used to measure the direct neutron yield and the neutrons scattered from various targets; the neutron source and the detectors were shielded with layers of lead, stainless steel, and borated polyethylene to shield against the X-rays and neutrons. One of the plastic scintillators was set at 70[supercript]o and two were set at 110[superscript]o from the line of the neutron beam; a bare [superscript]3He tube was used for detecting scattered thermal neutrons. Twelve metal cans of one-gallon each containing four explosive surrogates and eight inert materials were used as targets. Nine materials in five-gallon cans including three explosive surrogates were also used. The SBRS method indicated a capability to distinguish the explosive surrogates in both experiments, although the five gallon targets gave more accurate results. The MCNP code was used to validate the experimental work and to simulate real explosives. The simulations indicated the possibility to use the time of flight (TOF) technique in future experimental work, and were able to distinguish all the real explosives from the inert materials.

<div>For decades nuclear fusion space propulsion has been studied but due to technological set backs for self-sustaining fusion, it has been repeatedly abandoned in favor of more near-term or present day solutions. While these present day solutions of chemical and electric propulsion have been able to accomplish their missions, as the human race looks to explore Mars, a near term solution utilizing nuclear fusion propulsion must be sought as the fusion powered thruster case currently does not meet the minimum 0.2 thrust-to-weight ratio requirement. The current work seeks to investigate the use of a ssion powered magnetic fusion thruster for a manned Mars mission with an emphasis on creating a very near-term propulsion system. This will be accomplished by utilizing present day readily available technology and adapting methods of nuclear electric and nuclear fusion propulsion to build this ssion assisted propulsion system. Near term solutions have been demonstrated utilizing both DT and D-He3 fuels for a ssion powered and ssion assisted Dense Plasma Focus fusion device capable of achieving thrust-to-weight ratios greater than 0.2 for V's of 20 km/s. The Dense Plasma Focus can achieve thrust-to-weight ratios of 0.34 and 0.4 for ssion assisted and ssion powered cases, respectively, however, the Gasdynamic Mirror device proved to be an infeasible design as a ssion powered thruster due to the increased weight of a ssion reactor.</div>

Thomas J. Fessenden. / Issued also as a thesis, M.I.T. Dept. of Electrical Engineering, April 29, 1961." "August 29, 1961." / Bibliography: p. 50-51. / Army Signal Corps Contract DA36-039-sc-78108. Dept. of the Army Task 3-99-20-001 and Project 3-99-00-000.