Download or read book Near Plume Laser Induced Fluorescence Velocity Measurements of a 600 W Hall Thruster Preprint written by and published by . This book was released on 2008 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work presents the near exit plane velocity field of the Busek Company BHT-600-Circular 600 W Hall thruster at a single operating condition with a 300 V anode potential. The xenon ion propellant velocities were measured using laser induced fluorescence of the 5d[4]7/2 - 6p[3] 5/2 excited state xenon ionic transition at 834.72 nm. Ion velocities were interrogated from the acceleration channel exit plane to a distance 100 mm from the exit plane (1.6 exit plane diameters). Both axial and radial velocities were directly measured. A nearly uniform axial velocity profile of approximately 17,000 m/s (197 eV) was measured at the acceleration channel center on the exit plane. The maximum axial velocity was measured 100 mm from the exit plane at 19,800 m/s (267 eV). Radial velocity measurements were used to determine the divergence of the plume, as well as in conjunction with the coaxial symmetry of the thruster to determine azimuthal velocities in several regions proximate to the exit plane. The 475 m/s mean azimuthal velocity was measured 5 mm from the exit plane. From this value, it is possible to estimate a maximum thruster induced torque of 3.2 x 10(exp.-5) Nm. Due to the divergence and convergence of the coaxial ion flow, distinct ion populations were observed to interact in the central core of the near plume. This is apparent in measurement volumes where multiple radial and axial velocity components were measured. These regions also typically correspond with the brightest portions of the visible plume.

Download or read book Laser Induced Fluorescence Velocity Measurements of a Low Power Cylindrical Hall Thruster written by and published by . This book was released on 2009 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work presents a preliminary survey of the axial velocities within the acceleration channel and axial, radial and azimuthal velocities in the plume of a Princeton University low power cylindrical Hall thruster. Xenon ion velocities for the thruster are derived from laser-induced fluorescence measurements of the 5d[4]7/2-6p[3]5/2 xenon ion excited state transition. Three operating conditions are considered with variations to the magnetic field strength and chamber background pressure in an effort to capture their effects on ion acceleration and centerline ion energy distributions. Under nominal conditions, xenon ions are accelerated to an energy of 25 eV within the thruster with an additional 188 eV gain in the thruster plume. At a position 40 mm into the plume, this constitutes an energy of 213 eV at an applied potential of 300 V. Decreasing the magnetic field strength appears to reduce the magnitude of radial ion velocities and pushes the peak electric field downstream into the plume. Increasing the background pressure is shown to reduce the plume divergence, move the peak electric field upstream towards the thruster exit plane, and result in a higher centerline axial ion velocity in the far-field of the plume.

Download or read book Laser induced Fluorescence Measurement of Ion Velocities in the Plume of a Hall Effect Thruster written by George J. Williams and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Interior and Exterior Laser Induced Fluorescence and Plasma Measurements Within a Hall Thruster Postprint written by and published by . This book was released on 2002 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: We describe results of a study of emissive-probe-based plasma potential measurements and laser-induced fluorescence velocimetry of neutral and singly ionized xenon in the plume and interior portions of the acceleration channel of a Hall thruster plasma discharge operating at powers ranging from 250 to 725 W. Axial ion and neutral velocity profiles for four discharge voltage conditions (100, 160, 200, and 250V) are measured as are radial ion velocity profiles in the near-field plume. Axial ion velocity measurements both inside and outside the thruster as well as radial velocity measurements outside the thruster are performed using laser-induced fluorescence with nonresonant signal detection. Neutral axial velocity measurements are similarly performed in the interior of the Hall thruster with resonance fluorescence collection. Optical access to the interior of the Hall thruster is provided by a 1-mm-wide axial slot in the outer insulator wall. The majority of the ion velocity measurements used partially saturated fluorescence to improve the signal-to-noise ratio. Probe-based plasma potential measurements extend from 50 mm outside the thruster exit plane to the near anode region for all but the highest discharge voltage condition. For each condition, the axial electric field is calculated from the plasma potential, and the local electron temperature is determined from the difference between the floating and plasma potentials. These two sets of measurements delineate the structure of the plasma and indicate that the ionization and acceleration regions are somewhat separated. Also, these measurements indicate a region of low electric field near the thruster exit, especially at the higher discharge voltages. This region of near constant potential (low electric field) may be a result of oscillations, which enhance the local plasma conductivity.

Download or read book Laser Induced Fluorescence Measurements Within a Laboratory Hall Thruster Postprint written by and published by . This book was released on 1999 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper, we describe the results of a study of laser induced fluorescence velocimetry of ionic xenon in the plume and interior acceleration channel of a laboratory Hall type thruster operating at powers ranging from 250 to 725 W. Optical access to the interior of the Hall thruster is provided by a 1 mm axial slot in the insulator outer wall. Axial ion velocity profiles for four discharge voltages (100 V, 160 V, 200 V, 250 V) are measured as are radial velocity profiles in the near field plume. Internal neutral xenon axial velocity profiles are also measured at these conditions. For each test condition, the implied axial electric field is calculated from the measured ionic velocity profiles. These results are compared to previous plasma potential measurements performed with an emissive probe. The correspondence between the two sets of measurements indicates that the ionization and acceleration regions within the thruster are separated to some degree.

Download or read book Laser Induced Fluorescence Measurements on a Laboratory Hall Thruster Postprint written by and published by . This book was released on 1998 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper, we describe the results of a study of laser induced fluorescence velocimetry of neutral xenon in the plume of a Hall type thruster operating at powers ranging from 250 to 725 W. Neutral velocities are seen to increase with thruster discharge voltage. There is no evidence for neutrals being accelerated in the near field plume. Velocities appear to remain constant past the cathode plane. In preparation for future ion velocimetry studies, the plume plasma potential profile is measured for a number of conditions. For a low power condition, the plasma potential profile is mapped through the ionization region into the interior of the thruster. For this condition, the electric field profile is calculated. We also find evidence of neutral xenon streaming toward the Hall thruster. These backstreaming neutrals make determination of neutral xenon velocities difficult. We believe the neutrals originate from the thruster plume wall impingement approximately 2 m from the thruster.

Download or read book Deconvolution of Ion Velocity Distributions from Laser induced Fluorescence Spectra of Xenon Electrostatic Thruster Plumes written by Timothy B. Smith and published by . This book was released on 2003 with total page 614 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laser induced Fluorescence Measurements of a Two stage Electrothermal Thruster Plume written by Vincent P. Chiravalle and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterization of Electric Thruster Plumes Using Multiplexed Laser Induced Fluorescence Measurements written by W. M. Ruyten and published by . This book was released on 1992 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Establishing a Facility for Making Non Intrusive Near Real Time Electric Propulsion Thruster Erosion Measurements Via Simultaneous Two Frequency Laser Induced Fluorescence written by and published by . This book was released on 2002 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: DURIP funds were used to purchase three cryopumps, a state-of-the-art tunable-diode laser, a dye-to-Ti:sapphire conversion kit for a ring laser (for enhanced IR capability), and a commercial ion-sputtering source. The new cryopumps increased the xenon pumping speed of the Large Vacuum Test Facility (LVTF) at the University of Michigan's Plasmadynamics and Electric Propulsion Laboratory (PEPL) from 140,000 to 240,000 1/s. The new lasers will be used in conjunction with our tunable ring laser to make Two-Wavelength Simultaneous Laser Induced Fluorescence (TWSLIF) measurements for Hall thruster discharge channel erosion characterization. TWSLIF will first be demonstrated in a smaller vacuum facility with a commercial ion source and a boron nitride substrate. Once perfected in the smaller chamber, TWSLIF will be used in the LVTF to characterize discharge channel erosion of the P5 Hall thruster. This capability will not only enhance PEPL, but will establish a national facility where thruster erosion and spacecraft integration issues are investigated.

Download or read book Laser Induced Fluorescence Characterization of Cusped Field Plasma Thrusters written by Natalia Adrienne MacDonald and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cusped field plasma thrusters are a recent development in electrostatic propulsion, aimed at improving operation in the low power regime. Several diagnostic techniques have been employed to characterize these discharges. The present study focuses on the use of laser induced fluorescence to map ion velocities throughout the plumes of several cusped field thruster variants. Laser induced fluorescence provides the opportunity to probe small plasma sources with high spatial resolution, and is particularly useful for studying plasma propulsion devices where hot, energetic and highly non-uniform environments can adversely affect intrusive probes. The first half of this thesis focuses on time-averaged laser induced fluorescence velocimetry for three cusped-field thrusters. While a time-averaged velocity diagnostic is adequate in determining overall performance, it cannot resolve the dynamics seen in oscillatory modes of thruster operation. The second half of this research focuses on the development of an advanced CW laser induced fluorescence diagnostic technique, capable of correlating high frequency current fluctuations to the resulting fluorescence excitation lineshapes. This method is validated using simulations and a 60 Hz xenon spectral lamp. It is then applied to an oscillatory mode of the diverging cusped field thruster. Results show that the positions of the ionization and peak acceleration regions in the thruster vary over the course of a discharge current oscillation, causing the ion velocities to fluctuate in time. This new method of time-synchronized CW laser-induced fluorescence will be invaluable for better understanding the dynamics of thruster operation as well as other quasi-periodic oscillatory discharges, in fields from combustion to materials processing, among others.

Download or read book Temperature and Velocity Diagnostic for an Arcjet Plume Using Laser induced Fluorescence written by John Gary Liebeskind and published by . This book was released on 1994 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laser induced Fluorescence Measurements Within an Arcjet Thruster Nozzle written by P. Victor Storm and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laser induced Fluorescence Modulation Technique for Velocity Measurements in Gas Flows written by Christoph Johannes Hassa and published by . This book was released on 1985 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Performance Evaluation of the SPT 140 written by and published by . This book was released on 1997 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laser induced Fluorescence Diagnostics for Xenon Hall Thrusters written by R. J. Cedolin and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Plasma Potential and Langmuir Probe Measurements in the Near Field Plume of the Nasa 300m Hall Thruster written by Daniel A. Herman and published by BiblioGov. This book was released on 2013-06 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to aid in the design of high-power Hall thrusters and provide experimental validation for existing modeling efforts, plasma potential and Langmuir probe measurements were performed in the near-field plume of the NASA 300M Hall thruster. A probe array consisting of a Faraday probe, Langmuir probe, and emissive probe was used to interrogate the plume from approximately 0.1 - 2.0 DT, m downstream of the thruster exit plane at four operating conditions: 300 V, 400 V, and 500 V at 20 kW as well as 300 V at 10 kW. Results show that the acceleration zone and high-temperature region were contained within 0.3 DT, m from the exit plane at all operating conditions. Isothermal lines were shown to strongly follow magnetic field lines in the nearfield, with maximum temperatures ranging from 19 - 27 eV. The electron temperature spatial distribution created large drops in measured floating potentials in front of the magnetic pole surfaces where the plasma density was small, which suggests strong sheaths at these surfaces. The data taken have provided valuable information for future design and modeling validation, and complements ongoing internal measurement efforts on the NASA 300