Pub Date : 1989-05-22DOI: 10.1109/PLASMA.1989.166120
W. Khachen, J. Laghari
Summary form only. Kapton film is commonly used as an electrical and thermal insulator in most spacecraft. The voltages associated with space power systems are projected to increase above the Paschens minimum voltage in the future. Coupled with the low-pressure environment around the spacecraft, a glow discharge could possibly take place in the vicinity of the conductor. Such a discharge can cause slow and gradual degradation of the insulating film possibly leading to an electrical or thermal failure. In this study, Kapton was subjected to glow discharge aging in a low-pressure environment, and changes in its electrical and morphological properties were monitored. No significant changes in the properties were found to occur in the film over a short period of time, showing that Kapton is suitable as an electrical insulator for high-voltage applications in space.<>
{"title":"Glow discharge aging of Kapton film","authors":"W. Khachen, J. Laghari","doi":"10.1109/PLASMA.1989.166120","DOIUrl":"https://doi.org/10.1109/PLASMA.1989.166120","url":null,"abstract":"Summary form only. Kapton film is commonly used as an electrical and thermal insulator in most spacecraft. The voltages associated with space power systems are projected to increase above the Paschens minimum voltage in the future. Coupled with the low-pressure environment around the spacecraft, a glow discharge could possibly take place in the vicinity of the conductor. Such a discharge can cause slow and gradual degradation of the insulating film possibly leading to an electrical or thermal failure. In this study, Kapton was subjected to glow discharge aging in a low-pressure environment, and changes in its electrical and morphological properties were monitored. No significant changes in the properties were found to occur in the film over a short period of time, showing that Kapton is suitable as an electrical insulator for high-voltage applications in space.<<ETX>>","PeriodicalId":165717,"journal":{"name":"IEEE 1989 International Conference on Plasma Science","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117346713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-05-22DOI: 10.1109/PLASMA.1989.166157
V. Ayres, J. Choe, K. Boulais, H. Uhm
A self-consistent nonlinear analysis of an axis-encircling electron beam in a vane circuit oscillator has been made. Optimized quantities with respect to energy, current, vane depth, and magnetic field have been determined and compared with experiment. The analysis also includes more realistic parameters, such as the off-centering effect and the tapering of the magnetic field. Three specific sources of off-centering have been identified: (1) an unbalanced magnetic field reversal, (2) a finite-span magnetic transition, and (3) a finite upstream Larmor radius. The effects of these sources of off-centering on an ideal configuration (balanced field reversal, zero-span cusp and constant up- and downstream magnetic fields) have been investigated. For the peniotron mechanism to dominate over the competing negative mass instability, a near-ideal axis-encircling electron beam is required. Tolerances for off-centering effects causing deviation from ideal have been investigated. Magnetic tapering has been investigated both as a realistic experimental parameter and for the purposes of designing an adiabatic compression, which has been shown to reduce the off-centering effect.<>
{"title":"Nonlinear studies of axis-encircling electron beam with off-centering and field tapering effects","authors":"V. Ayres, J. Choe, K. Boulais, H. Uhm","doi":"10.1109/PLASMA.1989.166157","DOIUrl":"https://doi.org/10.1109/PLASMA.1989.166157","url":null,"abstract":"A self-consistent nonlinear analysis of an axis-encircling electron beam in a vane circuit oscillator has been made. Optimized quantities with respect to energy, current, vane depth, and magnetic field have been determined and compared with experiment. The analysis also includes more realistic parameters, such as the off-centering effect and the tapering of the magnetic field. Three specific sources of off-centering have been identified: (1) an unbalanced magnetic field reversal, (2) a finite-span magnetic transition, and (3) a finite upstream Larmor radius. The effects of these sources of off-centering on an ideal configuration (balanced field reversal, zero-span cusp and constant up- and downstream magnetic fields) have been investigated. For the peniotron mechanism to dominate over the competing negative mass instability, a near-ideal axis-encircling electron beam is required. Tolerances for off-centering effects causing deviation from ideal have been investigated. Magnetic tapering has been investigated both as a realistic experimental parameter and for the purposes of designing an adiabatic compression, which has been shown to reduce the off-centering effect.<<ETX>>","PeriodicalId":165717,"journal":{"name":"IEEE 1989 International Conference on Plasma Science","volume":"105 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123693706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-05-22DOI: 10.1109/PLASMA.1989.166149
H. Takikawa, T. Sakuta, M. Boulos
In-flight measurements of the principal particle parameters of size, velocity, and temperature are made for nickel powders with a mean diameter of 76 mu m, processed in a 3-MHz inductively coupled RF plasma torch. The diagnostic technique is based on the real-time observation of a particle through its own emission of Planck radiation. Measurements were carried out in the plasma plume, 340-mm downstream from the point of injection of the powder for plasma powers of 10 and 20 kW and pressures of 170 and 340 torr. The mean velocity and the surface temperature increased from 44 to 60 m/s and from 2400 to 2500 K, respectively, with the increase of the plasma power from 10 to 20 kW at 170 torr. The particle velocity decreased from 44 to 27 m/s and the surface temperature increased from 2400 to 2500 K with the increase in pressure from 170 to 340 torr at 10 kW. Cross-correlation analysis showed that the particle undergoing plasma processing has a higher surface temperature when its size is small and its velocity is low.<>
{"title":"In-flight diagnostics of thermal treatment of powders in induction plasmas","authors":"H. Takikawa, T. Sakuta, M. Boulos","doi":"10.1109/PLASMA.1989.166149","DOIUrl":"https://doi.org/10.1109/PLASMA.1989.166149","url":null,"abstract":"In-flight measurements of the principal particle parameters of size, velocity, and temperature are made for nickel powders with a mean diameter of 76 mu m, processed in a 3-MHz inductively coupled RF plasma torch. The diagnostic technique is based on the real-time observation of a particle through its own emission of Planck radiation. Measurements were carried out in the plasma plume, 340-mm downstream from the point of injection of the powder for plasma powers of 10 and 20 kW and pressures of 170 and 340 torr. The mean velocity and the surface temperature increased from 44 to 60 m/s and from 2400 to 2500 K, respectively, with the increase of the plasma power from 10 to 20 kW at 170 torr. The particle velocity decreased from 44 to 27 m/s and the surface temperature increased from 2400 to 2500 K with the increase in pressure from 170 to 340 torr at 10 kW. Cross-correlation analysis showed that the particle undergoing plasma processing has a higher surface temperature when its size is small and its velocity is low.<<ETX>>","PeriodicalId":165717,"journal":{"name":"IEEE 1989 International Conference on Plasma Science","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122104154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-05-22DOI: 10.1109/PLASMA.1989.166281
E. Montalvo, R. Carrera, M. Rosenbluth
Small and large versions of the basic IGNITEX ignition experiment have been proposed and analyzed. The basic IGNITEX machine is a high-field, compact, single-turn tokamak with a high plasma current. This tokamak machine uses unconventional magnet and power supply systems that allow the generation of the high magnetic field required for ohmic ignition. The design is based on the assumption that Kaye-Goldston (L-mode) energy confinement time scaling represents adequately the possible confinement degradation induced by alpha particle heating. The basic IGNITEX experiment has high ignition margin for present scaling expressions but it is not designed to ignite under the more pessimistic Goldston scaling. Along these lines, the IGNITEX concept can be divided into two alternatives: (1) a small, minimum-cost machine in which the relevant confinement scaling is the saturated neoalcator (without degradation due to alpha heating) expression, and (2) a larger machine that can handle enough plasma current to produce a reasonable ignition margin with the L-mode Goldston scaling. This larger machine will satisfy the most restrictive requirements.<>
{"title":"Small and large versions of the IGNITEX experiment","authors":"E. Montalvo, R. Carrera, M. Rosenbluth","doi":"10.1109/PLASMA.1989.166281","DOIUrl":"https://doi.org/10.1109/PLASMA.1989.166281","url":null,"abstract":"Small and large versions of the basic IGNITEX ignition experiment have been proposed and analyzed. The basic IGNITEX machine is a high-field, compact, single-turn tokamak with a high plasma current. This tokamak machine uses unconventional magnet and power supply systems that allow the generation of the high magnetic field required for ohmic ignition. The design is based on the assumption that Kaye-Goldston (L-mode) energy confinement time scaling represents adequately the possible confinement degradation induced by alpha particle heating. The basic IGNITEX experiment has high ignition margin for present scaling expressions but it is not designed to ignite under the more pessimistic Goldston scaling. Along these lines, the IGNITEX concept can be divided into two alternatives: (1) a small, minimum-cost machine in which the relevant confinement scaling is the saturated neoalcator (without degradation due to alpha heating) expression, and (2) a larger machine that can handle enough plasma current to produce a reasonable ignition margin with the L-mode Goldston scaling. This larger machine will satisfy the most restrictive requirements.<<ETX>>","PeriodicalId":165717,"journal":{"name":"IEEE 1989 International Conference on Plasma Science","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117093716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-05-22DOI: 10.1109/PLASMA.1989.166270
N. Hershkowitz, M. Cho, J. Pruski, J. Dekock, P. Anderson
Glow discharges are produced in a conventional parallel-plate device using either propylene or argon. The propylene discharge differs from the argon discharge in that polymers are continuously deposited at the plasma boundaries. Discharges with plasma densities of approximately 10/sup 9/ cm/sup -3/, T/sub e/ approximately=3 eV are produced at neutral pressures of approximately 300 mtorr at RF frequencies of approximately 100 kHz. The device consists of two parallel plates (diameter=7.5 cm, separation approximately 5 cm). Langmuir probe current-voltage (I-V) characteristics are monitored with a heated mesh probe. A PC monitors the I-V characteristic every 30 s and adjusts the gain of the glow discharge RF amplifier to maintain a desired I-V characteristic as wall conditions, etc. change.<>
{"title":"Feedback control of a polymer producing glow discharge plasma","authors":"N. Hershkowitz, M. Cho, J. Pruski, J. Dekock, P. Anderson","doi":"10.1109/PLASMA.1989.166270","DOIUrl":"https://doi.org/10.1109/PLASMA.1989.166270","url":null,"abstract":"Glow discharges are produced in a conventional parallel-plate device using either propylene or argon. The propylene discharge differs from the argon discharge in that polymers are continuously deposited at the plasma boundaries. Discharges with plasma densities of approximately 10/sup 9/ cm/sup -3/, T/sub e/ approximately=3 eV are produced at neutral pressures of approximately 300 mtorr at RF frequencies of approximately 100 kHz. The device consists of two parallel plates (diameter=7.5 cm, separation approximately 5 cm). Langmuir probe current-voltage (I-V) characteristics are monitored with a heated mesh probe. A PC monitors the I-V characteristic every 30 s and adjusts the gain of the glow discharge RF amplifier to maintain a desired I-V characteristic as wall conditions, etc. change.<<ETX>>","PeriodicalId":165717,"journal":{"name":"IEEE 1989 International Conference on Plasma Science","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125978300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-05-22DOI: 10.1109/PLASMA.1989.165961
J. H. Whealton, R. Raridon, P. Ryan
Summary form only. The Vlasov-Maxwell equations in the Lorentz gauge and in the quasi-electrostatic limit have been considered on ion time scales in 4-6 dimensions (including nu ), subject to certain boundary and volume conditions. The sheath physics near a Faraday shield has been studied under this formulation. Several Faraday shield configurations, including the Perkins, TFTR, and JET shields, have been studied, focusing on scenarios and conditions affecting metallic impurity generation.<>
{"title":"Plasma sheath modeling near an ICRF Faraday shield","authors":"J. H. Whealton, R. Raridon, P. Ryan","doi":"10.1109/PLASMA.1989.165961","DOIUrl":"https://doi.org/10.1109/PLASMA.1989.165961","url":null,"abstract":"Summary form only. The Vlasov-Maxwell equations in the Lorentz gauge and in the quasi-electrostatic limit have been considered on ion time scales in 4-6 dimensions (including nu ), subject to certain boundary and volume conditions. The sheath physics near a Faraday shield has been studied under this formulation. Several Faraday shield configurations, including the Perkins, TFTR, and JET shields, have been studied, focusing on scenarios and conditions affecting metallic impurity generation.<<ETX>>","PeriodicalId":165717,"journal":{"name":"IEEE 1989 International Conference on Plasma Science","volume":"2013 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128172700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-05-22DOI: 10.1109/PLASMA.1989.166089
F. Wessel, A. Fisher, N. Rostoker, J. Song
In a transverse magnetic field a tenuous plasma beam follows a curved Lorentzian trajectory. In contrast, a collisionless dense beam propagates undeflected by collective plasma processes including diamagnetic flux exclusion and the E*B drift. In recent laboratory and space experiments the magnetic field has been observed to diffuse much more rapidly than classically predicted, even in the limit of high beta and small ion gyroradius where diamagnetic flux exclusion is normally expected. In space experiments the mechanism for rapid diffusion has been attributed to a lower hybrid drift instability. However, in laboratory experiments the instability growth time is too long to account for the observations. Solving the nonlinear magnetic diffusion equation gives a conductivity substantially reduced from its classical value by the square of the plasma collisionality parameter. The resulting diffusion time scale is more consistent with experimental observations. Rapid diffusion is also observed for high-beta beam propagation in a magnetized plasma. By varying the background plasma density the perpendicular conductivity can be increased to a value that prevents polarized E*B propagation. The measured limits for complete shorting agree with a dynamic calculation of the beam polarization and shorting time scales and has resulted in an analytic expression for the ratio of beam to plasma density.<>
{"title":"Plasma motion into a transverse magnetic field and plasma","authors":"F. Wessel, A. Fisher, N. Rostoker, J. Song","doi":"10.1109/PLASMA.1989.166089","DOIUrl":"https://doi.org/10.1109/PLASMA.1989.166089","url":null,"abstract":"In a transverse magnetic field a tenuous plasma beam follows a curved Lorentzian trajectory. In contrast, a collisionless dense beam propagates undeflected by collective plasma processes including diamagnetic flux exclusion and the E*B drift. In recent laboratory and space experiments the magnetic field has been observed to diffuse much more rapidly than classically predicted, even in the limit of high beta and small ion gyroradius where diamagnetic flux exclusion is normally expected. In space experiments the mechanism for rapid diffusion has been attributed to a lower hybrid drift instability. However, in laboratory experiments the instability growth time is too long to account for the observations. Solving the nonlinear magnetic diffusion equation gives a conductivity substantially reduced from its classical value by the square of the plasma collisionality parameter. The resulting diffusion time scale is more consistent with experimental observations. Rapid diffusion is also observed for high-beta beam propagation in a magnetized plasma. By varying the background plasma density the perpendicular conductivity can be increased to a value that prevents polarized E*B propagation. The measured limits for complete shorting agree with a dynamic calculation of the beam polarization and shorting time scales and has resulted in an analytic expression for the ratio of beam to plasma density.<<ETX>>","PeriodicalId":165717,"journal":{"name":"IEEE 1989 International Conference on Plasma Science","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128267921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-05-22DOI: 10.1109/PLASMA.1989.166084
A. Peratt
The extrapolation of observed plasma densities, magnetic and electric field strengths, and energies in near-Earth and solar system plasmas to regions beyond the reach of spacecraft has led to the concept of a plasma universe. The importance of applying electromagnetism and plasma physics to the problem of radiogalaxy, galaxy, and star formation derives from the fact that the Universe is largely matter in its plasma state. The motion of this plasma across weak magnetic fields can lead to the generation of electromotive forces, the energy of which can be transported over large distances by Birkeland currents. The dissipation of this energy in localized regions can lead to pinches and condensed states of matter. Where double layers form in the pinches, strong electric fields can accelerate the charged particles to high energies. The evolution of a filamentary plasma universe has been studied, and direct comparisons of simulation, laboratory, space, and astrophysical data have been made.<>
{"title":"The plasma universe","authors":"A. Peratt","doi":"10.1109/PLASMA.1989.166084","DOIUrl":"https://doi.org/10.1109/PLASMA.1989.166084","url":null,"abstract":"The extrapolation of observed plasma densities, magnetic and electric field strengths, and energies in near-Earth and solar system plasmas to regions beyond the reach of spacecraft has led to the concept of a plasma universe. The importance of applying electromagnetism and plasma physics to the problem of radiogalaxy, galaxy, and star formation derives from the fact that the Universe is largely matter in its plasma state. The motion of this plasma across weak magnetic fields can lead to the generation of electromotive forces, the energy of which can be transported over large distances by Birkeland currents. The dissipation of this energy in localized regions can lead to pinches and condensed states of matter. Where double layers form in the pinches, strong electric fields can accelerate the charged particles to high energies. The evolution of a filamentary plasma universe has been studied, and direct comparisons of simulation, laboratory, space, and astrophysical data have been made.<<ETX>>","PeriodicalId":165717,"journal":{"name":"IEEE 1989 International Conference on Plasma Science","volume":"41 12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128639240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-05-22DOI: 10.1109/PLASMA.1989.166293
H. Bauer, G. Kirkman, M. Gundersen
The population of atomic levels in a back-lighted thyratron (BLT) plasma with electron density of 1-5*10/sup 15/ cm/sup -3/ and current density of about 10/sup 4/ A/cm/sup 2/ was calculated, and line intensity ratios were compared with spectroscopic measurements. Simple considerations lead to a very small cathode fall width during the conduction phase, and the resulting high electric field can create fast electrons with energies of some 100 eV. From a solution of a Fokker-Planck equation, it was found that fast electrons can penetrate the gap region, which consists of a Maxwellian plasma with electron density of 10/sup 15/ cm/sup -3/ and electron temperature of 1-2 eV. The BLT plasma was modeled assuming a monoenergetic electric beam with a strong anisotropic velocity distribution function, which penetrates a low electric field region of a bulk plasma at thermal equilibrium and neutrals. The numerical solution of the appropriate set of rate equations, which also takes radiative processes into account, yields information about the beam and bulk plasma properties. The principal analysis can also be applied to the similar pseudospark switch.<>
{"title":"Modeling of the discharge plasma in a black lighted thyratron","authors":"H. Bauer, G. Kirkman, M. Gundersen","doi":"10.1109/PLASMA.1989.166293","DOIUrl":"https://doi.org/10.1109/PLASMA.1989.166293","url":null,"abstract":"The population of atomic levels in a back-lighted thyratron (BLT) plasma with electron density of 1-5*10/sup 15/ cm/sup -3/ and current density of about 10/sup 4/ A/cm/sup 2/ was calculated, and line intensity ratios were compared with spectroscopic measurements. Simple considerations lead to a very small cathode fall width during the conduction phase, and the resulting high electric field can create fast electrons with energies of some 100 eV. From a solution of a Fokker-Planck equation, it was found that fast electrons can penetrate the gap region, which consists of a Maxwellian plasma with electron density of 10/sup 15/ cm/sup -3/ and electron temperature of 1-2 eV. The BLT plasma was modeled assuming a monoenergetic electric beam with a strong anisotropic velocity distribution function, which penetrates a low electric field region of a bulk plasma at thermal equilibrium and neutrals. The numerical solution of the appropriate set of rate equations, which also takes radiative processes into account, yields information about the beam and bulk plasma properties. The principal analysis can also be applied to the similar pseudospark switch.<<ETX>>","PeriodicalId":165717,"journal":{"name":"IEEE 1989 International Conference on Plasma Science","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127549174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1989-05-22DOI: 10.1109/PLASMA.1989.166208
W. Williams, G. Miley
An investigation of nuclear pumping of ultraviolet (UV) fluorescent gases that can be used to power the optically pumped atomic iodine laser is discussed. This laser utilizes 230-330-nm UV irradiance to dissociate compounds such as CF/sub 3/I or C/sub 3/F/sub 7/I, resulting in lasing on the 5/sup 2/P/sub 1/2/-5/sup 2/P/sub 3/2/ transition of atomic iodine at 1.31 mu m. UV fluorescence can be produced by the interaction of energetic products from nuclear reactions with a fluorescing gas. This is called a nuclear pumped flashlamp (NPF). The goal of the present phase of this work is to select an optimal gas (or gas mixture), so that the fluorescence efficiency, coupled with the overlap between the fluorescer spectral output and the photodissociation cross section of the lasant, will be maximized. Using standard gas discharge emission data, the emission spectra for select pure gases have been analyzed and compared to the photodissociation spectra of CF/sub 3/I and C/sub 3/F/sub 7/I between 230 and 330 nm. Of the potentially suitable gases, neon shows the best overlap, followed by krypton, chlorine, radon, xenon, helium, and fluorine. The best overlap is approximately a factor of 25 greater than the worst. Excimer mixtures, which can have very high emission efficiencies around a particular wavelength, are also being investigated as likely candidates.<>
{"title":"Nuclear-induced UV fluorescence","authors":"W. Williams, G. Miley","doi":"10.1109/PLASMA.1989.166208","DOIUrl":"https://doi.org/10.1109/PLASMA.1989.166208","url":null,"abstract":"An investigation of nuclear pumping of ultraviolet (UV) fluorescent gases that can be used to power the optically pumped atomic iodine laser is discussed. This laser utilizes 230-330-nm UV irradiance to dissociate compounds such as CF/sub 3/I or C/sub 3/F/sub 7/I, resulting in lasing on the 5/sup 2/P/sub 1/2/-5/sup 2/P/sub 3/2/ transition of atomic iodine at 1.31 mu m. UV fluorescence can be produced by the interaction of energetic products from nuclear reactions with a fluorescing gas. This is called a nuclear pumped flashlamp (NPF). The goal of the present phase of this work is to select an optimal gas (or gas mixture), so that the fluorescence efficiency, coupled with the overlap between the fluorescer spectral output and the photodissociation cross section of the lasant, will be maximized. Using standard gas discharge emission data, the emission spectra for select pure gases have been analyzed and compared to the photodissociation spectra of CF/sub 3/I and C/sub 3/F/sub 7/I between 230 and 330 nm. Of the potentially suitable gases, neon shows the best overlap, followed by krypton, chlorine, radon, xenon, helium, and fluorine. The best overlap is approximately a factor of 25 greater than the worst. Excimer mixtures, which can have very high emission efficiencies around a particular wavelength, are also being investigated as likely candidates.<<ETX>>","PeriodicalId":165717,"journal":{"name":"IEEE 1989 International Conference on Plasma Science","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132992754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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