Download or read book Laser Induced Fluorescence of Neutral Xenon in the Near Field of a 200 W Hall Thruster written by and published by . This book was released on 2005 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work presents measurements of neutral xenon velocity in the plume of the Busek Company BHT-200-X3 200 W Hall thruster at a single 250 V anode potential operating condition. The xenon velocities were measured using laser induced fluorescence of the 6s'1/20/1 -6p'3/22 excited state transition at 834.68 nm. Velocities were interrogated near the exit plane of the anode discharge and in the vicinity of the cathode. Both axial and radial velocities were measured simultaneously using phase sensitive detection. The exit plane axial velocity varies from 350-50 m/s near the outer acceleration channel radius to approximately 150 m/s at the inner radius. The radial velocity at the outer insulator is approximately zero, but increases to approximately 100 m/s directed away from the protruding central magnetic pole at the inner insulator. This is consistent with the creation of neutrals at the inner radius by ions neutralized following a wall collision with the protruding central magnetic pole. Neutral velocities downstream of the exit plane also show a radial velocity away from the central magnetic pole. However, this behavior may be due to the influence of the cathode plume. Velocity measurements in the cathode plume show that xenon velocities reach in excess of 610 m/s. Since the cathode flow represents a substantial portion of the thruster flow and is only weakly ionized, the cathode plume may influence the neutral velocities nearer the anode. Evidence of interaction between the two flows takes the form of widened fluorescence line profiles which may indicate the collisional mixing disparate neutral streams or possibly several gas dynamic shocks.

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 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 of Velocity Within a Hall Discharge written by and published by . This book was released on 2001 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of a study of 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 are described. Axial ion and neutral velocity profiles for four discharge voltage conditions (100V, 160V, 200V, 250V) are measured as are radial ion velocity profiles in the near-field plume.

Download or read book Interior and Exterior Laser Induced Fluorescence and Plasma Potential Measurements on a Laboratory Hall Thruster Postprint written by and published by . This book was released on 1999 with total page 16 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 comparison, the plume plasma potential profile is measured with an emissive probe. These probe based potential measurements extend from 50 mm outside the plume 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. In addition, an estimate of the local electron temperature is calculated from the Bohm criterion at the location of each plasma potential measurement.

Download or read book 41st AIAA ASME SAE ASEE Joint Propulsion Conference Exhibit 10 13 July 2005 Tucson Arizona 05 4400 05 4449 written by and published by . This book was released on 2005 with total page 566 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 Study of a Xenon Hall Thruster written by R. J. Cedolin and published by . This book was released on 1997 with total page 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 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 30th Plasmadynamics and Lasers Conference written by and published by . This book was released on 1999 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 35th AIAA ASME SAE ASEE Joint Propulsion Conference and Exhibit written by and published by . This book was released on 1999 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Journal of Propulsion and Power written by and published by . This book was released on 2008 with total page 666 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2001 with total page 850 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fundamentals of Electric Propulsion written by Dan M. Goebel and published by John Wiley & Sons. This book was released on 2008-12-22 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: Throughout most of the twentieth century, electric propulsion was considered the technology of the future. Now, the future has arrived. This important new book explains the fundamentals of electric propulsion for spacecraft and describes in detail the physics and characteristics of the two major electric thrusters in use today, ion and Hall thrusters. The authors provide an introduction to plasma physics in order to allow readers to understand the models and derivations used in determining electric thruster performance. They then go on to present detailed explanations of: Thruster principles Ion thruster plasma generators and accelerator grids Hollow cathodes Hall thrusters Ion and Hall thruster plumes Flight ion and Hall thrusters Based largely on research and development performed at the Jet Propulsion Laboratory (JPL) and complemented with scores of tables, figures, homework problems, and references, Fundamentals of Electric Propulsion: Ion and Hall Thrusters is an indispensable textbook for advanced undergraduate and graduate students who are preparing to enter the aerospace industry. It also serves as an equally valuable resource for professional engineers already at work in the field.

Download or read book Two Photon Absorption Laser Induced Fluorescence for Neutral Hydrogen Profile Measurements written by and published by . This book was released on 2016 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: The magnitude and spatial dependence of neutral density in magnetic confinement fusion experiments is a key physical parameter, particularly in the plasma edge. Modeling codes require precise measurements of the neutral density to calculate charge-exchange power losses and drag forces on rotating plasmas. However, direct measurements of the neutral density are problematic. In this work, we proposed to construct a laser-based diagnostic capable of providing spatially resolved measurements of the neutral density in the edge of plasma in the DIII-D tokamak. The diagnostic concept is based on two-photon absorption laser induced fluorescence (TALIF). By injecting two beams of 205 nm light (co or counter propagating), ground state hydrogen (or deuterium or tritium) can be excited from the n = 1 level to the n = 3 level at the location where the two beams intersect. Individually, the beams experience no absorption and therefore have no difficulty penetrating even dense plasmas. After excitation, a fraction of the hydrogen atoms decay from the n = 3 level to the n = 2 level and emit photons at 656 nm (the H[alpha] line). Calculations based on the results of previous TALIF experiments in magnetic fusion devices indicated that a laser pulse energy of approximately 3 mJ delivered in 5 ns would provide sufficient signal-to-noise for detection of the fluorescence. In collaboration with the DIII-D engineering staff and experts in plasma edge diagnostics for DIII-D from Oak Ridge National Laboratory (ORNL), WVU researchers designed a TALIF system capable of providing spatially resolved measurements of neutral deuterium densities in the DIII-D edge plasma. The laser systems were specified, purchased, and assembled at WVU. The TALIF system was tested on a low power hydrogen discharge at WVU and the plan was to move the instrument to DIII-D for installation in collaboration with ORNL researchers. After budget cuts at DIII-D, the DIII-D facility declined to support installation on their tokamak. Instead, after a no-cost extension, the apparatus was moved to the University of Washington-Seattle and successfully tested on the HIT-SI3 spheromak experiment. As a result of this project, TALIF measurements of the absolutely calibrated neutral density hydrogen and deuterium were obtained in a helicon source and in a spheromak, designs were developed for installation of a TALIF system on a tokamak, and a new, xenon-based calibration scheme was proposed and demonstrated. The xenon-calibration scheme eliminates significant problems that were identified with the standard krypton calibration scheme.