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Dec 2002

Volume 73, Issue 12, pp. 4057-4404

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back to top NUCLEAR PHYSICS, FUSION and PLASMAS

Generation and control of field-aligned flow velocity shear in a fully ionized collisionless plasma

T. Kaneko, Y. Odaka, E. Tada, and R. Hatakeyama

Rev. Sci. Instrum. 73, 4218 (2002); http://dx.doi.org/10.1063/1.1518791 (5 pages) | Cited 15 times

Online Publication Date: 21 November 2002

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A modified plasma-synthesis method is developed in order to actively control an ion flow energy along magnetic-field lines, where ion and electron emitters of the same diameter are oppositely set at cylindrical machine ends and the ion emitter is concentrically segmented into three sections. The field-aligned ion flows with radially different energies, or ion flow velocity shears, are generated in a radially uniform plasma potential when each section of the segmented ion emitter is individually biased at a positive value above the plasma potential. © 2002 American Institute of Physics.
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52.30.-q Plasma dynamics and flow

Thomson scattering diagnostic of solid density plasmas using x-ray lasers

H. A. Baldis, J. Dunn, M. E. Foord, and W. Rozmus

Rev. Sci. Instrum. 73, 4223 (2002); http://dx.doi.org/10.1063/1.1515386 (6 pages) | Cited 10 times

Online Publication Date: 21 November 2002

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In this article, we demonstrate through calculations and theoretical analysis the first application of an x-ray laser for probing hot, high-density plasmas (ne ≥ 1023 cm−3) using a Ni-like transient collisional excitation x-ray laser as a probe. Theoretical predictions are used to diagnose the electron temperature in short-pulse (500 fs) laser-produced plasmas. The threshold power of the x-ray probe is estimated by comparing theoretical scattering levels with plasma thermal emission. The necessary spectral resolution of the instrument sufficient for resolving electron temperature is given. Effects of the electron heat flow on the ion-acoustic fluctuation spectra are presented. The outlook for these and next generation experiments are discussed. © 2002 American Institute of Physics.
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52.70.La X-ray and γ-ray measurements
42.55.Vc X- and γ-ray lasers
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.65.-y Plasma simulation

Imaging system for low-density plasma by heterodyne interferometer with fan beam microwave

H. Ito, N. Yugami, Y. Nishida, and W. Sakai

Rev. Sci. Instrum. 73, 4229 (2002); http://dx.doi.org/10.1063/1.1516833 (3 pages) | Cited 2 times

Online Publication Date: 21 November 2002

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A microwave imaging system based on a heterodyne interferometer has been developed to measure the spatial distribution of the plasma density without introducing any direct disturbance to the plasma by employing a diode array scattering technique. The imaging system with the use of a fan beam microwave for a radar system demonstrates the principle of the technique by placing finite-size dielectric phantoms instead of the plasma between the horn antenna and the diode antenna array. Experimental results show that very good image of the objects can be reconstructed and the system is equivalent to popularly known multichannel imaging system. As a result, it is possible to make simple, low-cost, and compact microwave interferometer for measuring the spatial distribution of the plasma density. © 2002 American Institute of Physics.
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52.70.Gw Radio-frequency and microwave measurements

Probe measurements of ion energy distribution in magnetized plasmas

S. V. Ratynskaia, V. I. Demidov, and K. Rypdal

Rev. Sci. Instrum. 73, 4232 (2002); http://dx.doi.org/10.1063/1.1516854 (5 pages) | Cited 7 times

Online Publication Date: 21 November 2002

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A probe method for measurement of the ion energy distribution in magnetized plasmas is proposed. A cylindrical probe with end plugs is oriented parallel to the magnetic field and used to reduce the electron contribution to the total probe current. The contribution of ions to the second derivative of the total current is identified by experiments with different probe orientation and strength of the magnetic field. The ion density obtained from the measured ion energy distribution is in good agreement with the electron density obtained from measured electron energy distribution. © 2002 American Institute of Physics.
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52.70.Ds Electric and magnetic measurements
52.25.Xz Magnetized plasmas

First measurement of neutron emission profile on JT-60U using Stilbene neutron detector with neutron-gamma discrimination

M. Ishikawa, T. Nishitani, A. Morioka, M. Takechi, K. Shinohara, M. Shimada, Y. Miura, M. Nagami, and Yu. A. Kaschuck

Rev. Sci. Instrum. 73, 4237 (2002); http://dx.doi.org/10.1063/1.1518145 (6 pages) | Cited 14 times

Online Publication Date: 21 November 2002

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This article describes a diagnostic for measuring neutron emission profile in JT-60U. The Stilbene neutron detector, developed by TRINITI laboratory in Russia, has been installed on the JT-60U Tokamak to measure the neutron emission profile for the first time. The Stilbene neutron detector is a detector which combines a Stilbene crystal scintillator with a neutron-gamma pulse shape discrimination circuit, with a very compact size. Performance tests were carried out using neutron and gamma-ray source prior to installation on JT-60U. Good gamma suppression of the Stilbene neutron detector was verified. Though the neutron emission profile obtained by Stilbene neutron detectors has error of 30% in innermost channel with a calculation using measured plasma parameters, there is an agreement within 10% error in the other channels. © 2002 American Institute of Physics.
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29.40.Mc Scintillation detectors
28.52.Lf Components and instrumentation
89.30.Jj Nuclear fusion power

Measurements of the nonthermal x-ray emission in the T-10 tokamak using CdTe detectors

P. V. Savrukhin

Rev. Sci. Instrum. 73, 4243 (2002); http://dx.doi.org/10.1063/1.1519938 (3 pages) | Cited 3 times

Online Publication Date: 21 November 2002

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A diagnostic technique based on sets of CdTe detectors is used for measurements of spatial localization and temporal evolution of the nonthermal (Eγ up to 150 keV) x-ray emission in plasma with high density in the T-10 tokamak. Various types of x-ray bursts observed during the density limit disruption appear as a result of the forward bremsstrahlung due to nonthermal electron interaction with the residual plasma as well as to nonuniform interaction of the runaway electrons with the plasma-facing constructions. © 2002 American Institute of Physics.
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52.70.La X-ray and γ-ray measurements
52.55.Fa Tokamaks, spherical tokamaks
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
52.40.Hf Plasma-material interactions; boundary layer effects
07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors
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