摘要:

A3He ionization chamber was used to measure neutron spectra on TFTR during 1987. The ion temperature was deduced for one set of Ohmically heated plasmas and agreed within 20% with that measured by other diagnostics. The absolute efficiency was calibrated using a d–d neutron generator.

ISSN:0034-6748    

DOI:10.1063/1.1140094

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Plasma diagnostics employing energetic lithium beams are in routine use on several present‐day tokamak experiments. These measurements are constrained by the availability of a suitable lithium ion source. Necessary and/or desirable parameters include narrow energy spread, high‐emission current density, simplicity, and long lifetime. The existing ion gun on the TEXT experiment uses the thermionic emitter &bgr;‐eucryptite and meets the above requirements, except for being limited to a useful emission of about 4 mA. We will present design criteria and accelerator results for a new ion gun capable of 15‐mA emission based on an increased emitter area. Important design considerations are the thermal and mechanical properties of the large (∼20 cm2) emitter area and the ion optics required to focus the emitted flux into a beam of ∼1‐cm2cross section. The potential improvement in the performance of both the TEXT and ASDEX diagnostic systems will be discussed.

ISSN:0034-6748    

DOI:10.1063/1.1140095

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The Wien filter is anE×Bdeflecting analyzer with the electrostatic field perpendicular to the magnetostatic field. The twofold functions of the Wien filter are as an energy analyzer as well as a mass analyzer. It has very high resolution for paraxial charged particle beams withV=E/B, the Wien velocity. Two Wien filters were built and tested for electrons up to 3.5 keV and protons beams of 200 eV. The performance of the two is compared and appears to have features useful for high‐temperature plasma diagnostics including simultaneous measurement of energy and mass spectra and high resolution.

ISSN:0034-6748    

DOI:10.1063/1.1140097

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

This article reviews digital spectral analysis techniques that yield experimental insight into plasma turbulence. Methods to quantify the statistical properties of the fluctuations and to measure the particle and heat flux caused by electrostatic fluctuations are presented. Furthermore, analysis techniques to study the nonlinear coupling process of turbulence and the redistribution of energy among the different modes are discussed. The impact of the analysis techniques on fusion research is demonstrated with experimental results collected with Langmuir probes, heavy‐ion beam probes, and laser scattering in the tokamak TEXT. Special emphasis is given to the characterization of the wavenumber distribution and the correlation lengths in all toroidal directions, including a first measurement ofk∥in a tokamak.

ISSN:0034-6748    

DOI:10.1063/1.1140098

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The primary mission of the Compact Ignition Tokamak (CIT) is to study the physics of alpha‐particle heating in an ignited D–T plasma. A burn time of about 10 &tgr;Eis projected in a divertor configuration with base‐line machine design parameters ofR=2.10 m,a=0.65 m,b=1.30 m,Ip=11 MA,BT=10 T, and 10–20 MW of auxiliary rf heating. Plasma temperatures and density are expected to reachTe(0)∼20 keV,Ti(0)∼30 keV, andne(0)∼1×1021m−3. The combined effects of restricted port access to the plasma, the presence of severe neutron and gamma radiation backgrounds, and the necessity for remote handling of in‐cell components create challenging design problems for all of the conventional diagnostics associated with tokamak operations. In addition, new techniques must be developed to diagnose the evolution in space, time, and energy of the confined alpha distribution as well as potential plasma instabilities driven by collective alpha‐particle effects. The design effort for CIT diagnostics is presently in the conceptual phase, with activity being focused on the selection of a viable diagnostic set and the identification of essential research and development projects to support this process. A review of these design issues and other aspects impacting the selection of diagnostic techniques for the CIT experiment will be presented.

ISSN:0034-6748    

DOI:10.1063/1.1140099

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

A plasma fluctuation signal analysis software package is described that surmounts common difficulties by using an information‐hiding method and a layered structure.This approach leads to portability and easy customization for experimentalists who are not necessarily experts in signal analysis. The software contents and examples of applications to actual experimental data will be discussed.

ISSN:0034-6748    

DOI:10.1063/1.1140100

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The objective of this paper is to present a systematic comparison of the conventional fast Fourier transform and maximum entropy method (MEM) of spectral estimation of turbulent plasma fluctuation data. On the basis of this comparison, it appears that the MEM is the preferred approach for the spectral analysis of short time duration fluctuation records.

ISSN:0034-6748    

DOI:10.1063/1.1140101

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Digital complex demodulation techniques are used to generate time‐varying auto‐ and cross‐power spectra which, in turn, are useful in characterizing the time‐frequency characteristics of nonstationary plasma fluctuation data. The approach is illustrated with fluctuation data measured with a heavy‐ion beam probe on the TMX experiment.

ISSN:0034-6748    

DOI:10.1063/1.1140102

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

We present a method of using a plasma model to fit a given profile and using the model’s parameters to generate the profile seen along any alternate chord. We illustrate the method with a simple ‘‘linearly shifted circle’’ model in which it is assumed that the plasma cross sections are circles that are shifted along the major radius of the vacuum vessel as a linear function of their radii. Sample test results are provided.

ISSN:0034-6748    

DOI:10.1063/1.1140103

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

A multipurpose image processing system has been developed for the Advanced Toroidal Facility (ATF) stellarator experiment. This system makes it possible to investigate the complicated topology inherent in stellarator plasmas with conventional video technology. Infrared (IR) and charge‐coupled device (CCD) cameras, operated at the standard video framing rate, are used on ATF to measure heat flux patterns to the vacuum vessel wall and visible‐light emission from the ionized plasma. These video cameras are coupled with fast acquisition and display systems, developed for a MicroVAX‐II, which allow between‐shot observation of the dynamic temperature and spatial extent of the plasma generated by ATF. The IR camera system provides acquisition of one frame of 60×80 eight‐bit pixels every 16.7 ms via storage in a CAMAC module. The CCD data acquisition proceeds automatically, storing the video frames until its 12‐bit, 1‐Mbyte CAMAC memory is filled. After analysis, transformation, and compression, selected portions of the data are stored on disk. Interactive display of experimental data and theoretical calculations are performed with software written in Interactive Data Language.

ISSN:0034-6748    

DOI:10.1063/1.1140104

出版商:AIP    

年代:1988

数据来源: AIP