25 research outputs found
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Evaluation of a high power submillimeter pulsed laser system
This report describes the selection, development, and testing of the system components and presents the power and frequency profiles achieved in tests made on the assembled system. These results, and knowledge gained through design and development work, have suggested improvements in design characteristics to be applied to future research on this diagnostic method. (MOW
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Far-infrared interferometry/polarimetry on the ISX-B tokamak
Theoretical analyses have shown that the current density distribution in a tokamak plasma can be obtained indirectly by the measurement of the poloidal magnetic field created by the current flowing in the plasma discharge. The distribution of this field may be determined by projecting linearly polarized far-infrared (FIR) laser beams through the plasma and measuring the Faraday rotation of the polarization. Since the rotation angle of the polarization vector is proportional to the line integral of electron density times the poloidal magnetic field along the path, the electron density profile must also be measured simultaneously in order to unfold the current distribution. The amount of Faraday rotation expected in a typical plasma experiment is calculated to be on the order of 5 to 10 degrees. Therefore the authors have constructed a multichord modulated FIR polarimeter/interferometer that measures both the phase delay of four laser beams passing through a plasma discharge and the instantaneous polarization of these same beams. The phase shift of each of the beams is directly proportional to the line-averaged electron density and the polarization rotation is directly proportional to the line-averaged density times poloidal field
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Calibration of the FIR polarimeter on TFTR tokamak
The results of the first Faraday rotation measurement on the TFTR tokamak are presented. Data are reported on ohmic- as well as neutral-beam-heated plasmas including solid pellet injections. The procedure and the results of the calibration are described. The effects of various errors in the measurements as well as the problem of cross coupling laser beams are studied
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Submillimeter wave propagation in tokamak plasmas
The propagation of submillimeter-waves (smm) in tokamak plasmas has been investigated both theoretically and experimentally to ensure successful measurements of electron density and plasma current distributions in tokamak devices. Theoretical analyses have been carried out to study the polarization of the smm waves in TFTR and ISX-B tokamaks. A multichord smm wave interferometer/polarimeter system has been employed to simultaneously measure the line electron density and poloidal field-induced Faraday rotation in the ISX-B tokamak. The experimental study on TFTR is under way. Computer codes have been developed and have been used to study the wave propagation and to reconstruct the distributions of plasma current and density from the measured data. The results are compared with other measurements
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Submillimeter wave propagation in tokamak plasmas
The propagation of submillimeter-waves (smm) in tokamak plasmas has been investigated both theoretically and experimentally to ensure successful measurements of electron density and plasma current distributions in tokamak devices. Theoretical analyses have been carried out to study the polarization of the smm waves in TFTR and ISX-B tokamaks. A multichord smm wave interferometer/polarimeter system has been employed to simultaneously measure the line electron density and poloidal field-induced Faraday rotation in the ISX-B tokamak. The experimental study on TFTR is under way. Computer codes have been developed and have been used to study the wave propagation and to reconstruct the distributions of plasma current and density from the measured data. The results are compared with other measurements
Optimal values of rovibronic energy levels for triplet electronic states of molecular deuterium
Optimal set of 1050 rovibronic energy levels for 35 triplet electronic states
of has been obtained by means of a statistical analysis of all available
wavenumbers of triplet-triplet rovibronic transitions studied in emission,
absorption, laser and anticrossing spectroscopic experiments of various
authors. We used a new method of the analysis (Lavrov, Ryazanov, JETP Letters,
2005), which does not need any \it a priory \rm assumptions concerning the
molecular structure being based on only two fundamental principles:
Rydberg-Ritz and maximum likelihood. The method provides the opportunity to
obtain the RMS estimates for uncertainties of the experimental wavenumbers
independent from those presented in original papers. 234 from 3822 published
wavenumber values were found to be spurious, while the remaining set of the
data may be divided into 20 subsets (samples) of uniformly precise data having
close to normal distributions of random errors within the samples. New
experimental wavenumber values of 125 questionable lines were obtained in the
present work. Optimal values of the rovibronic levels were obtained from the
experimental data set consisting of 3713 wavenumber values (3588 old and 125
new). The unknown shift between levels of ortho- and para- deuterium was found
by least squares analysis of the , ,
rovibronic levels with odd and even values of . All the energy levels were
obtained relative to the lowest vibro-rotational level (, ) of
the electronic state, and presented in tabular form together
with the standard deviations of the empirical determination. New energy level
values differ significantly from those available in literature.Comment: 46 pages, 9 picture
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Configuration control, fluctuations, and transport in low-collisionality plasmas in the ATF Torsatron
In low-collisionality plasmas confined in tokamaks and stellarators, instabilities driven by particles trapped in inhomogeneities of the magnetic fields could be important in increasing plasma transport coefficients. In the Advanced Toroidal Facility (ATF), an {ell} = 2, M = 12 field-period stellarator device with major radius R = 2.1 m, average plasma minor radius a = 0.27 m, central and edge rotational transforms {chi}{sub 0} {approx} 0.3, {chi}{sub a} {approx} 1, the effects of electron trapping in the helical stellarator field are expected to be important in plasmas with {bar n}{sub e} {approx} 5 {times} 10{sup 12} cm{sup {minus}3}, T{sub e0} {approx} 1 keV. Such plasmas have already been sustained for long-pulses (20 s) using 150--400 kW of 53.2-GHz ECH power at B = 0.95 T. Transport analysis shows that for {rho} = r/a {le} 1/3, the electron anomalous transport is {le}10 times the neoclassical value, while at {rho} = 2/3 it is 10--100 times neoclassical; this is compatible with expectations for transport enhancement due to dissipative trapped-electron modes. 4 refs., 3 figs
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A two-wavelength infrared interferometer/polarimeter system for CIT (Compact Ignition Tokamak)
The results of a fasiblity study of a two-wavelength infrared interferometerpolarimeter system for measurements of electron density and plasma current profiles in the Compact Ignition Tokamak (CIT) are presented. The system utilizes CO/sub 2/ lasers at a wavelength of 10.6 ..mu..m, and water-vapor lasers at 28 ..mu..m. Both magneto-optic and electro-optic polarization-modulation techniques have been used to determine the sensitivity and time response of the polarimetry at 10.6 ..mu..m. Measurement of a simulated plasma Faraday rotation demonstrated a sensitivity of approximately 0.01)degree) for a CO/sub 2/ laser polarimeter with an electrooptic CdTe crystal modulator. 3 refs., 4 fig
PRECISION DETERMINATION OF THE VELOCITY OF LIGHT BY A BAND SPECTRUM METHOD
Author Institution: Department of Physics, Pennsylvania State CollegeThe velocity of light has been measured by precision measurement of obtained from the 004 and 103 bands of the rotation vibration system of HCN. The ratio of microwave to infrared is identically equal to the velocity of light. A description of the experiments and statistical methods of treating the data will be given. The result obtained by this method is km/sec