TMX-U (Tandem Mirror Experiment-Upgrade) Tandem-mirror Thermal-barrier Experiments

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Book Synopsis TMX-U (Tandem Mirror Experiment-Upgrade) Tandem-mirror Thermal-barrier Experiments by :

Download or read book TMX-U (Tandem Mirror Experiment-Upgrade) Tandem-mirror Thermal-barrier Experiments written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermal-barrier experiments have been carried out in the Tandem Mirror Experiment-Upgrade (TMX-U). Measurements of nonambipolar and ambipolar radial transport show that these transport processes, as well as end losses, can be controlled at modest densities and durations. Central-cell heating methods using ion-cyclotron heating (ICH) and neutral-beam injection have been demonstrated. Potential mesurements with recently developed methods indicate that deep thermal barriers can be established.

TMX-U Tandem-Mirror Thermal-barrier Experiments

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Book Synopsis TMX-U Tandem-Mirror Thermal-barrier Experiments by :

Download or read book TMX-U Tandem-Mirror Thermal-barrier Experiments written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermal-barrier experiments have been carried out in the Tandem Mirror Experiment-Upgrade (TMX-U). Measurements of nonambipolar and ambipolar radial transport show that these transport processes, as well as end losses, can be controlled at modest densities and durations. Central-cell heating methods using ion-cyclotron heating (ICH) and neutral-beam injection have been demonstrated. Potential measurements with recently developed methods indicate that deep thermal barriers can be established.

Tandem Mirror Experiment Upgrade (TMX-U) Overview-recent Events

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Book Synopsis Tandem Mirror Experiment Upgrade (TMX-U) Overview-recent Events by :

Download or read book Tandem Mirror Experiment Upgrade (TMX-U) Overview-recent Events written by and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Since its construction and commissioning was completed in the winter of 1981, the Tandem Mirror Experiment Upgrade (TMX-U) has been conducting tandem mirror thermal barrier experiments. The work, following the fall of 1983 when strong plugging with thermal barriers was achieved, has been directed toward controlling radial transport and forming thermal barriers with high density and Beta. This paper describes the overall engineering component of these efforts. Major changes to the machine have included vacuum improvements, changes to the Electron and Ion Cyclotron Resonance Heating systems (ECRH and ICRH), and the installation of a Plasma Potential Control system (PPC) for radial transport reduction. TMX-U operates an extensive diagnostics system that acquires data from 21 types of diagnostic instruments with more than 600 channels, in addition to 246 machine parameters. The changes and additions will be presented. The closing section of this paper will describe the initial study work for a proposed TMX-U octupole configured machine.

Vacuum Measurements on the Tandem Mirror Experiment Upgrade (TMX-U) Fusion Experiment

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Book Synopsis Vacuum Measurements on the Tandem Mirror Experiment Upgrade (TMX-U) Fusion Experiment by :

Download or read book Vacuum Measurements on the Tandem Mirror Experiment Upgrade (TMX-U) Fusion Experiment written by and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The gas inventory of the Tandem Mirror Experiment Upgrade (TMX-U) must be carefully controlled, if it is to successfully create various plasma configurations for thermal-barrier experiments designed to provide an improved performance for tandem-mirror experiments. This paper is a progress report on the calibration methods and pressure measurements of machine conditions deriving from recently improved neutral-beam gas control, and changes to the internal baffling geometry and the gettering system.

Recent Experimental Progress in the TMX-U Thermal Barrier Tandem Mirror Experiment

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Book Synopsis Recent Experimental Progress in the TMX-U Thermal Barrier Tandem Mirror Experiment by :

Download or read book Recent Experimental Progress in the TMX-U Thermal Barrier Tandem Mirror Experiment written by and published by . This book was released on 1984 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent experiments on the TMX-U thermal barrier device at LLNL have achieved the end plugging of axial ion losses up to a central cell density of n/sub c/ = 2 x 1012 cm. During these tests, the axial potential profile characteristic of a thermal barrier has been measured experimentally, indicating an ion-confining potential greater than 1.5 kV and a potential depression of 0.45 kV in the barrier region. The average beta of hot electrons in the thermal barrier has been increased to 15% and appears limited only by classical scattering and ECRH pulse duration. Furthermore, deuterium ions in the central cell have been heated with ICRF to an average energy of 1.5 keV, with a heating efficiency of 40%. During strong end plugging, the axial ion confinement time reached 50 to 100 ms while the nonambipolar radial ion confinement time was 5 to 15 ms - independent of end plugging. Radial ion confinement time exceeding 100 ms has been attained on shots without end plugging. Plates, floated electrically on the end walls, have increased the radial ion confinement time by a factor of 1.8. Further improvement in the central cell density during end plugging can be expected by increasing the ICRF, improving the central cell vacuum conditions and beam heating efficiency, and increasing the radial extent of the potential control plates on the end walls.

Microstability of TMX-U During Initial Thermal Barrier Operation

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Book Synopsis Microstability of TMX-U During Initial Thermal Barrier Operation by :

Download or read book Microstability of TMX-U During Initial Thermal Barrier Operation written by and published by . This book was released on 1984 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: During the initial thermal barrier experiments on the Tandem Mirror Experiment-Upgrade (TMX-U), we successfully demonstrated the principle of improved axial tandem mirror confinement achieved by establishment of both the thermal barrier and the ion confining potential peak. During this operation, we created both hot (100-keV) mirror-confined electron and hot (8-keV) mirror-confined ion populations in the end cells. In certain parameter ranges, we observed these species to be weakly unstable to various microinstabilities, but we did not observe clear evidence for an absolute limit to confinement.

Initial TMX-U Thermal-barrier Experiments

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Book Synopsis Initial TMX-U Thermal-barrier Experiments by :

Download or read book Initial TMX-U Thermal-barrier Experiments written by and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes results from the initial thermal barrier experiments in the Tandem Mirror Experiment-Upgrade (TMX-U). Strong end plugging has been produced using a combination of ECRH gyrotrons with sloshing ion beam injection. Plugging has been achieved with a central cell higher than that of the end plugs. In these low-density central cell experiments (7 x 1011 cm−3) the axial losses (tau/sub parallel to/ = 20 to 80 ms) are smaller than the radial losses (tau/sub perpendicular to/ = 4 to 8 ms). Although no direct measurements are yet available to determine if a thermal barrier potential dip is generated, these experiments support many theoretical features of the thermal barrier concept.

Construction and Operational Experience of the Tandem Mirror Experiment-Upgrade (TMX-U).

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Book Synopsis Construction and Operational Experience of the Tandem Mirror Experiment-Upgrade (TMX-U). by :

Download or read book Construction and Operational Experience of the Tandem Mirror Experiment-Upgrade (TMX-U). written by and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Tandem Mirror Experiment-Upgrade (TMX-U) incorporates two new features at Lawrence Livermore National Laboratory (LLNL) tandem mirror program, thermal barriers in the end plugs and injection of the neutral beams at several oblique angles. The thermal barriers isolate the electrons in the end plugs from those in the central cell, making it possible to heat them independently with microwaves. In addition, this innovation produces a large potential gradient in the end plugs with lower magnetic fields and lower neutral-beam energies than would be possible in a conventional tandem mirror device. The TMX-U is also designed to test neutral-beam-injection angles as an experimental parameter. We use angles other than 90° to produce a plasma with improved microstability.

TMX Tandem-mirror Experiments and Thermal-barrier Theoretical Studies

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Book Synopsis TMX Tandem-mirror Experiments and Thermal-barrier Theoretical Studies by :

Download or read book TMX Tandem-mirror Experiments and Thermal-barrier Theoretical Studies written by and published by . This book was released on 1982 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes recent analysis of energy confinement in the Tandem Mirror Experiment (TMX). TMX data also indicates that warm plasma limits the amplitude of the anisotropy driven Alfven ion cyclotron (AIC) mode. Theoretical calculations show strong AIC stabilization with off-normal beam injection as planned in TMX-U and MFTF-B. This paper reports results of theoretical analysis of hot electrons in thermal barriers including electron heating calculations by Monte Carlo and Fokker-Planck codes and analysis of hot electron MHD and microinstability. Initial results from the TMX-U experiment are presented which show the presence of sloshing ions.

Tandem Mirror Thermal Barrier Experimental Program Plan

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Book Synopsis Tandem Mirror Thermal Barrier Experimental Program Plan by :

Download or read book Tandem Mirror Thermal Barrier Experimental Program Plan written by and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes an experimental plan for the development of the Tandem Mirror Thermal Barrier. Included is: (1) a description of thermal barrier related physics experiments; (2) thermal barrier related experiments in the existing TMX and Phaedrus experiments; (3) a thermal barrier TMX upgrade; and (4) initiation of investigations of axisymmetric magnetic geometry. Experimental studies of the first two items are presently underway. Results are expected from the TMX upgrade by the close of 1981 and from axisymmetric tandem mirror experiments at the end of 1983. Plans for Phaedrus upgrades are developing for the same period.

Experimental Results from TMX-U. [Tandem Mirror Experiment-Update].

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Book Synopsis Experimental Results from TMX-U. [Tandem Mirror Experiment-Update]. by :

Download or read book Experimental Results from TMX-U. [Tandem Mirror Experiment-Update]. written by and published by . This book was released on 1987 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents the recent results from the Tandem Mirror Experiment-Update(TMX-U). Many of these results can be divided into two major areas: (1) axial confinement and plasma potential, and (2) radial transport and total confinement (i.e., particle balance). Among the key observations to be discussed are the following: When the ion-confining potential theta/sub ic/ is small, theta/sub ic//T/sub i/ approx. 1 to 2, the axial confinement time scales as the theoretical Pastukhov time. Deep thermal barriers (theta/sub b/ approx. 0.7 kV, theta/sub b//T/sub e/ approx. 6 to 7) have been measured, but there is no strong correlation between ion-confining potential and the thermal-barrier depth. By installing a calibrated H/sub .cap alpha./ emission diagnostic to measure the ionization current, we have quantified particle balance between the ionization source current and the four plasma current channels: (1) axial losses, (2) nonambipolar radial losses, (3) ambipolar radial losses, and (4) density changes. All current channels are directly measured except for the ambipolar current, which is inferred from the particle balance equation. TMX-U operation above 1 to 3 x 1012 cm−3 is dominated by current channel (1) and below 1 x 1012 cm−3 by one or more of the remaining three channels. Central-cell particle buildup has been observed for one or two e-foldings and, within the radial core, found consistent with particle balance.

TMX-U Experimental Results

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Book Synopsis TMX-U Experimental Results by :

Download or read book TMX-U Experimental Results written by and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes results from the Tandem Mirror Experiment-Upgrade (TMX-U). Mirror-confined electrons with 30 to 70 keV mean energy densities of 0.5 to 2.0 x 1012 cm−3 and average betas of 3 to 5% are produced using electron-cyclotron resonant heating (ECRH). These results are consistent with an electron Fokker-Planck code. Improved ion-cyclotron microstability is observed using neutral beam injection at 47° to the magnetic axis, rather than at 90° as in the previous experiment, TMX. Strong end plugging has been produced using a combination of ECRH gyrotrons with sloshing-ion beam injection. In these low-density central cell experiments (3 x 1011 cm−3) the axial losses (tau/sub parallel/ = 20 to 80 ms) are smaller than the nonambipolar radial losses (tau/sub perpendicular/ = 4 to 8 ms). Plugging has been achieved with a central cell density double that of the end plugs. Although no direct measurements are yet available to determine if a thermal barrier potential dip is generated, these experiments support many theoretical features of the thermal barrier concept.

Thermal Barrier Confinement Experiments in the TMX-U Tandem Mirror

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Book Synopsis Thermal Barrier Confinement Experiments in the TMX-U Tandem Mirror by :

Download or read book Thermal Barrier Confinement Experiments in the TMX-U Tandem Mirror written by and published by . This book was released on 1984 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In our recent experiments on the TMX-U thermal-barrier device, we achieved the end plugging of axial ion losses up to a central cell density of n/sub c/ = 6 x 1012 cm−3. During lower density experiments, we measured the axial potential profile characteristic of a thermal barrier and found an ion-confining potential greater than 1.5 kV and a potential depression of 0.45 kV in the barrier region. The average beta of hot end plug electrons has reached 15% and of hot central cell ions has reached 6%. In addition, we heated deuterium ions in the central cell with ICRF to an average perpendicular energy of 2 keV. During strong end plugging at low density (7 x 1011 cm−3), the axial ion confinement time tau/sub parallel/ reached 50 to 100 ms while the nonambipolar radial ion confinement time tau/sub perpendicular/ was 14 ms - independent of end plugging. Electrically floating end walls increased the radial ion confinement time by a factor of 1.8. At higher densities and lower potentials, tau/sub parallel/ was 6 to 12 ms and tau/sub perpendicular/ exceeded 100 ms.

Thermal Barrier Confinement Experiments in TMX-U Tandem Mirror. Revision 1

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Book Synopsis Thermal Barrier Confinement Experiments in TMX-U Tandem Mirror. Revision 1 by :

Download or read book Thermal Barrier Confinement Experiments in TMX-U Tandem Mirror. Revision 1 written by and published by . This book was released on 1984 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In our recent experiments on the TMX-U thermal-barrier device, we achieved the end plugging of axial ion losses up to a central cell density of n/sub c/ = 6 x 1012 cm−3. During lower density experiments, we measured the axial potential profile characteristic of a thermal barrier and found an ion-confining potential greater than 1.5 kV and a potential depression of 0.45 kV in the barrier region. The average beta of hot end plug electrons has reached 15% and of hot central cell ions has reached 6%. In addition, we heated deuterium ions in the central cell with ICRF to an average perpendicular energy of 2 keV. During strong end plugging at low density (7 x 1011 cm−3), the axial ion confinement time tau/sub parallel to/ reached 50 to 100 ms while the nonambiopolar radial ion confinement time tau/sub perpendicular to/ was 14 ms - independent of end plugging. Electrically floating end walls doubled the radial ion confinement time. At higher densities and lower potentials, tau/sub parallel to/ was 6 to 12 ms and tau/sub perpendicular to/ exceeded 100 ms.

Concepts and Development of Drift Pumping for the Tandem Mirror Experiment-Upgrade (TMX-U).

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Book Synopsis Concepts and Development of Drift Pumping for the Tandem Mirror Experiment-Upgrade (TMX-U). by :

Download or read book Concepts and Development of Drift Pumping for the Tandem Mirror Experiment-Upgrade (TMX-U). written by and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Low-energy ions trapped in the thermal barrier region of the TMX-U plasma cause a potential reduction which results in increased scattering and less thermal isolation between regions of the plasma. A method of removing these ions using magnetic field perturbations at the ion drift frequency has been developed. The concepts of ''drift pumping'' and hardware development are described in this paper. 5 refs., 7 figs.

Tandem Mirror Experiment-upgrade Vacuum System

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Book Synopsis Tandem Mirror Experiment-upgrade Vacuum System by :

Download or read book Tandem Mirror Experiment-upgrade Vacuum System written by and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Tandem Mirror Experiment-Upgrade (TMX-U) vacuum system has been installed and operating since December 1981. In 1982 and early 1983 the performance of the internal, dynamic pumping system was evaluated during physics experiments. The plasma region gas loads caused the pressure to exceed that allowable for achieving thermal barrier plasmas. The unified, multiple-beamline concept used on TMX-U to pump the neutral-beam injector gas was modified. The modifications to the system were designed to reduce conductance between the injectors and the plasma region to better use the differential pumping in the pumping regions. The modifications made were a smaller cross section neutralizer, replacing apertures with ducts between regions, eliminating the injector scrape-off in the plasma region, relocating the neutral beam dumps, and eliminating the gaps around various penetrations.

Review of the Tandem Mirror Experiment-Upgrade (TMX-U) Machine-parameter-instrumentation System

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Book Synopsis Review of the Tandem Mirror Experiment-Upgrade (TMX-U) Machine-parameter-instrumentation System by :

Download or read book Review of the Tandem Mirror Experiment-Upgrade (TMX-U) Machine-parameter-instrumentation System written by and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Tandem Mirror Experiment-Upgrade (TMX-U) machine consists of seven major machine subsystems: magnet system, neutral beam system, microwave heating (ECRH), ion heating (ICRH), gas fueling, stream guns, and vacuum system. Satisfactory performance of these subsystems is necessary to achieve the experimental objectives planned for TMX-U operations. Since the performance quality of the subsystem is important and can greatly affect plasma parameters, a 233-channel instrumentation system has been installed. Data from the instrumentation system are acquired and stored with the plasma diagnostic information. Thus, the details of the machine performance are available during post-shot analysis. This paper describes all the machine-parameter-instrumentation hardware, presents some typical data, and outlines how the data are used.