摘要:

AbstractThe ion sensitive probe to be presented is an electric probe for the measurement of the ion temperature or the ion energy distribution function of a magnetized plasma. At the same time, the electron temperature and the plasma potential can also be measured. The probe was tested experimentally in a large variety of plasmas, namely, Ne= (106−1014)/cm3, Ti, Te= (0.05 −100) eV and B = (0.1 −0.5) T. It functioned satisfactorily under the conditions where the ordinary Langmuir probes functioned well. The theory of the separate collection of ions will be presented, laying emphasis on the sheath effect, especially in a dense plasma. Experimentally obtained typical characteristics will be shown refering to critical structural parameters of the probe and corresponding plasma parameters. Results of some cross check experiments in temperature and plasma density measurements will be also rev

ISSN:0863-1042    

DOI:10.1002/ctpp.19960360112

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractA retarding field analyser (RFA) mounted on one of the JET reciprocating probe drives has been used to measure ion temperature in the boundary plasma. This paper describes the design of the RFA probe and special requirements for ion energy analysis. The first results are presented, together with the simulations by the DIVIMP code using the measurements of Langmuir probes at the divertor plates as input for the “Onion‐Skin” plasma

ISSN:0863-1042    

DOI:10.1002/ctpp.19960360113

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractAt the energies characteristic of the tokamak edge plasma, the Retarding Field Analyser (RFA) constitutes probably the simplest method of directly measuring the ion velocity distribution parallel to the magnetic field and the magnitude of the sheath potential fall. For the case of Maxwellian velocity distributions, the technique provides an estimate of the edge ion temperature. Despite their relative simplicity, care must be taken both to operate these devices correctly in the rather unique tokamak edge environment and to consider carefully the interpretation of data thus obtained. This contribution addresses some aspects of both of these issues using the results of RFA experiments conducted on the DITE tokamak.

ISSN:0863-1042    

DOI:10.1002/ctpp.19960360114

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractA double retarding field analyzer (DRA) was used for measuring electron distribution functions (EDFs) in the loss cone of an electron‐cyclotron‐resonance (ECR) discharge run in mixtures of He and N2. By integrating along ϵ =constlines, where ϵ =E‖+E⟂is the kinetic energy, the true electronenergydistribution functionF(ϵ) in the loss cone of the ECR discharge was determined. The shape ofF(ϵ) transforms from an exponential functions to a power law when changing plasma parameters like mixture ratio, total pressure and m

ISSN:0863-1042    

DOI:10.1002/ctpp.19960360115

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractSpheromaks are an alternative concept to tokamaks for the magnetic confinement of plasma, relying on internally generated magnetic fields and a close fitting highly conducting boundary for confinement rather than strong external magnetic fields. Applying well established double probe techniques, spatial and temporal electron temperature and density profiles are measured in the UMIST spheromak SPHEX. These are compared with estimates from spectroscopic diagnostics and a CO2interferometer. The results from the different diagnostics are in general agreement but differ in detail, the differences being interpreted as reflecting uncertainties both in the absolute calibration of the electron density determined from a Langmuir probe and in the comparison of point and line‐of‐sight measurements.A recent programme of titanium gettering has led to significant changes in our plasma parameters, and now there appears to be no consistency between these changes as observed by the probe and by the other diagnostics. This casts significant doubt on the reliability of the Langmuir probe techni

ISSN:0863-1042    

DOI:10.1002/ctpp.19960360116

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractFirst results from a movable Langmuir probe at the midplane of Asdex Upgrade are presented. We give a short description of the instrument and discuss the data evaluation. Langmiur probe interpretation is based on a nonlinear fit to an asymmetric double probe characteristic. Obtained radial profiles are compared with results of the Li‐beam and ECE diagnostics. A comparison with a scrape off layer decay length scaling for JET shows good agreement for low plasma densities, but significant deviations for high densities. Finally we show data obtained using a self emitting probe. This technique allows a direct measurement of the plasma potential close to the separatrix. The difference of floating and plasma potential is used for electron temperature determination. The results are in close agreement with the temperature derived directly from the Langmuir probe characteristics. Close to the separatrix a radial electric field of 70V/cmcan be derived from the measured plasma potentia

ISSN:0863-1042    

DOI:10.1002/ctpp.19960360117

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe JET reciprocating probe systems are described. This paper will also cover determination of separatrix position using the pressure balance method. Use of floating potential to indicate separatrix location is shown to be incorrect. Other topics covered are comparison of upstream profiles with both lithium beam and ‘onion‐skin’ modelling, experience with triple‐probe operation for ELM studies and the development of a boron‐nitride p

ISSN:0863-1042    

DOI:10.1002/ctpp.19960360118

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractSome applications of standard Langmuir probe techniques to determine the plasma density and electron temperature profiles and the frequency of drift wave like fluctuations in a Tokamak plasma are discussed with an attempt how the local particle transport caused due to this drift wave like fluctuation can be estimated. We also describe a possible method of measuring toroidal and poloidal rotation in a Tokamak plasma and the ion temperature by specially designed probes.

ISSN:0863-1042    

DOI:10.1002/ctpp.19960360119

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

ISSN:0863-1042    

DOI:10.1002/ctpp.19960360120

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractA view of the experimental techniques used in the characterization of fluctuations in the plasma boundary region of magnetic confinement systems by Langmuir probes is given. In particular, recent experimental developments for the measurement of electron temperature fluctuations are discussed.

ISSN:0863-1042    

DOI:10.1002/ctpp.19960360121

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY