Microwave Diagnostics

Meuth, H.

doi:10.1016/b978-0-12-067635-4.50010-7

Cited by 10 publications

(12 citation statements)

References 60 publications

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“…The purpose of this article is to review the microwave interferometry data obtained from the GEC reactor to date [ 4 – 6 ], including a description of the measurement methods and equipment. The latter will be briefly presented in the next section on the basic equations and equipment for the sake of completeness; but, several excellent chapters [ 3 , 7 – 10 ] and texts [ 11 , 12 ] on microwave diagnostic techniques convey both more general and in depth information which is not presented here. In the final section, representative data from plasmas through argon, helium, nitrogen and carbon tetrafluoride in the GEC reactor are given as a function of the rf current and time.…”

Section: Introductionmentioning

confidence: 99%

Microwave Diagnostic Results From the Gaseous Electronics Conference Rf Reference Cell

Overzet¹

1995

J. Res. Natl. Inst. Stand. Technol.

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Electron density measurements with even the simplest microwave interferometry techniques can range over three to four orders of magnitude, can be responsive on time scales as fast as 50 ns, and are simple to obtain and interpret. Three groups have published electron density data taken in the Gaseous Electronics Conference (GEC) reference reactor using microwave interferometry. The agreement in the data from these groups at higher pressures is excellent especially when one considers that the GEC reactors involved have some key differences. These may have been the cause of some differences between the results obtained at low pressures, although, the manner in which the measurements were interpreted may also have contributed. The electron densities compare favorably in argon, helium, and nitrogen above 33.3 Pa (250 mTorr); but, the measurements tend to diverge some at 13.3 Pa (100 mTorr) and in 133 Pa helium above approximately 200 mA. It is speculated that the latter difference occurs as the discharges change from a bulk ionization or α-mode to a secondary electron emission or γ-mode, and that this transition occurs at lower voltages and currents for reactors with aluminum electrodes than it does for those with stainless steel electrodes. In addition, time resolved electron densities are presented. There is agreement between time resolved measurements in the two reactors, in particular, the electron density in helium discharges is found to rise dramatically after the rf excitation is turned off while the electron densities in argon and nitrogen glows exhibit only slight increases.

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Section: Introductionmentioning

confidence: 99%

Microwave Diagnostic Results From the Gaseous Electronics Conference Rf Reference Cell

Overzet¹

1995

J. Res. Natl. Inst. Stand. Technol.

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“…More thorough treatment could be found in works by Huddleston& Leonard [83], Hutchinson [73], Meuth [84], and Auciello [85].…”

Section: D24 Boundary Conditionmentioning

confidence: 99%

Study of ICRF wave propagation and plasma coupling efficiency in a linear magnetic mirror device

Peng¹

1991

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_he Government reserves for itself and others acting on its behalf a r_alty free, nonexclusive, irrevocable, world-wide license for governmental purposes to publish, distribute, translate, duplicate, exhibit, and perform any such data coRyrighted the contractor. DISCLAIMERThis report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. ABSTRACTIon Cyclotron Range of Frequency (ICl%F) wave propagation in an inhomogeneous axial magnetic field in a cylindrical plasma-vacuum system has historically been inadequately modelled. Previous works either sacrifice the cylindrical geometry in favor of a simpler slab geometry [1], concentrate on the resonance region (mode conversion)[2], use a single mode to represent the entire field structure[Sl, or examine only radial propagation[4]. This thesis performs both analytical and computational studies to model the ICRF wave-plasma coupling and propagation problem. Experimental analysis is also conducted to compare experimental results with theoretical predictions.Both theoretical as well as experimental analysis are undertaken as part of the thesis. The theoretical studies simulate the propagation of ICRF waves in an axially inhomogeneous magnetic field and in cylindrical geometry. Two theoretical analysis are undertaken --an analytical study and a computational study. The analytical study treats the inhomogeneous magnetic field by transforming the (r,z) coordinate into another coordinate system (p,_) that allows the solution of the fields with much simpler boundaries (Plasma-vacuum boundary at p -1, conducting wall at p -_). The plasma fields are then Fourier transformed into two coupled convolution-integral equations which are then differenced and solved for both the perpendicular mode number a as well as the complete EM fields.The computational study involves a multiple eigenmode computational analysis of the fields that exist within the plasma-vacuum system. The inhomogeneous axial field is treated by dividing the geometry into a series of transverse axial slices and using a constant dielectric tensor in each individual slice. The slices are then connected by longitudinal boundary conditions. The experimental accomplishment of this thesis include the design_ construc- ICRF THEORY 6...

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“…The most fundamental property of plasmas is the electron density. Microwave-based measurements [2], as compared with electric probe-based techniques, have the advantage of being non-intrusive and less perturbative to the plasmas, i.e. without extracting currents from the plasma.…”

Section: Introductionmentioning

confidence: 99%

A transmission-line microwave interferometer for plasma electron density measurement

Chang

Hsieh

Wang

et al. 2006

Plasma Sources Sci. Technol.

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We present both the theoretical analysis and proof-of-principle experimental results of a novel transmission-line microwave interferometer for measurements of plasma electron density. The principle of this technique is the same as conventional microwave interferometers except that the sensing microwave propagates along a transmission-line structure. For this study, the transmission-line is a circular coaxial dielectric waveguide operated at 2.4 GHz. A microwave module consisting of a microwave source and a phase detector has also been developed for detecting the phase of the microwave propagating through the transmission-line. Good agreement of phase measurements between the microwave module and a microwave network analyser has been demonstrated. The electron density measured by the interferometer is also consistent with the results from a Langmuir probe.

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Microwave Diagnostics

Cited by 10 publications

References 60 publications

Microwave Diagnostic Results From the Gaseous Electronics Conference Rf Reference Cell

Microwave Diagnostic Results From the Gaseous Electronics Conference Rf Reference Cell

Study of ICRF wave propagation and plasma coupling efficiency in a linear magnetic mirror device

A transmission-line microwave interferometer for plasma electron density measurement

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