摘要:

Although diagnostic systems for the tokamak fusion test reactor (TFTR) must be compatible with high‐power experiments in deuterium–tritium (D–T) plasmas, it has been neither possible nor desirable to implement all the required features during the early phases of the facility. The research plan, the physical plant, instrumentation, and diagnostic techniques have all evolved during the past decade, and some of the original plans are no longer suitable. Preparations are now underway for D–T operation in TFTR in 1990. Among the activities necessary in support of the research plan are completion of the installation of the D–T diagnostic set, modification of diagnostic hardware to accommodate the ‘‘igloo’’ radiation shield of the torus, installation of auxiliary shielding for detectors and electronics, and enhancement of the reliability of specific components. These preparations and the final D–T diagnostic set for TFTR will be described.

ISSN:0034-6748    

DOI:10.1063/1.1140041

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The reverse‐bias current through a Pd‐MOS diode changes when hydrogen is present at the diode interface and this effect provides the bias for a solid‐state detector to monitor the flux and energy of hydrogen particles emanating from a beam or plasma. The addition of a coating atop the Pd forms a high‐pass energy filter and an array of coated Pd‐MOS diodes can function as a compact, hydrogen‐specific, energy spectrometer. The response characteristics of an Au‐coated Pd‐MOS diode array have been measured using a low‐energy hydrogen ion source. The array has several desirable characteristics for energetic hydrogen detection. Its response is dosimetric, it discriminates between hydrogen irradiations at different energies, and it can be regenerated by heating briefly to 100–200 °C. These properties make Pd‐MOS diode arrays attractive candidates for remote plasma‐edge flux and energy monitors in fusion devices.

ISSN:0034-6748    

DOI:10.1063/1.1140042

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

A nonlinear least‐squares curve‐fitting routine has been used to analyze single‐tip Langmuir probe measurements from the Tandem Mirror Experiment Upgrade during high‐density (≊1×1012cm−3) operation. This procedure provided estimates of uncertainties (variances) in the electron temperature and plasma density due to noise in the probe current. The electron temperature and plasma potential inferred from the fit were found to increase with the upper cutoff voltage used above a certain voltage. This effect appears to be due to a departure of the electron current from an exponentially increasing function for probe positions inside the limiter radius only. The fitted values for electron temperature and plasma density are consistent with previous measurements obtained with a double‐tipped probe and the fitted values of space potential indicate a linear relationship with electron temperature.

ISSN:0034-6748    

DOI:10.1063/1.1140043

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

A new diagnostic, composed of an array of high‐frequency magnetic probes, has been installed in TFTR for the study of waves driven by the ICRF heating antennas and waves generated spontaneously during ohmic and beam‐heated discharges. The former is of interest because of the possibility of surface wave generation by the heating antennas, and the latter because emission spectra may be useful as a beam ion or fusion product diagnostic. The array consists of seven fixed probes positioned at various toroidal and poloidal locations in order to obtain information about the corresponding wavenumbers in the edge region. Each probe consists of two orthogonal loops oriented to measureB&fgr;andB&thgr;. The array utilizes single‐turn loops with areas of 12 cm2and carefully selected signal processing elements to achieve a usable bandwidth of 1–500 MHz. Reduction of electrostatic pickup is accomplished by differentially combining signals from both ends of a loop using a wideband hybrid junction and by using an alumina shield to reduce capacitive coupling. The system permits simultaneous observation of both the magnetic and electrostatic components of the probe signal, allowing verification of the rejection ratio in a particular experiment. Details of the diagnostic design and experimental plans are discussed. This work was supported by U. S. DOE Contract No. DE‐AC02‐76‐CHO‐3073.

ISSN:0034-6748    

DOI:10.1063/1.1140045

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The interaction of the plasma with graphite limiters in fusion devices has been observed to lead to the formation of carbon film deposits. This occurs from the erosion of the graphite tiles in a high‐flux region and subsequent redeposition of the carbon atoms onto a low‐flux surface. The redeposition of carbon has strong ramifications on the in‐vessel tritium inventory. A commercially available quartz crystal monitor has been tested in a plasma simulator device to measure the flux of eroded carbon. The test was done with the intent of mounting such a detector in TFTR. The monitor measures the deposited film thickness as a change in the resonance frequency of the crystal. The plasma simulator is a Penning discharge operated with graphite electrodes. Initial tests show the crystal monitor has high sensitivity and can detect film thickness changes of a few angstroms. Thermal shock problems, however, may limit time resolution of the measurement and can provide only an integrated deposited thickness within a discharge. This work was supported by the U. S. DOE.

ISSN:0034-6748    

DOI:10.1063/1.1140046

出版商:AIP    

年代:1988

数据来源: AIP