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The Motional Stark Effect (MSE) diagnostic is a well established technique to infer the local internal magnetic field in fusion plasmas. In this paper, the existing forward model which describes the MSE data is extended by the Zeeman effect, fine-structure, and relativistic corrections in the interpretation of the MSE spectra for different experimental conditions at the tokamak ASDEX Upgrade. The contribution of the non-Local Thermodynamic Equilibrium (non-LTE) populations among the magnetic sub-levels and the Zeeman effect on the derived plasma parameters is different. The obtained pitch angle is changed by 3° ... 4° and by 0.5° ... 1° including the non-LTE and the Zeeman effects into the standard statistical MSE model. The total correction is about 4°. Moreover, the variation of the magnetic field strength is significantly changed by 2.2% due to the Zeeman effect only. While the data on the derived pitch angle still could not be tested against the other diagnostics, the results from an equilibrium reconstruction solver confirm the obtained values for magnetic field strength. [ABSTRACT FROM AUTHOR]

The prototype radio frequency source of the ITER heating neutral beams will be first tested in SPIDER test facility to optimize H-production, cesium dynamics, and overall plasma characteristics. Several diagnostics will allow to fully characterise the beam in terms of uniformity and divergence and the source, besides supporting a safe and controlled operation. In particular, thermal measurements will be used for beam monitoring and system protection. SPIDER will be instrumented with mineral insulated cable thermocouples, both on the grids, on other components of the beam source, and on the rear side of the beam dump water cooled elements. This paper deals with the final design and the technical specification of the thermal sensor diagnostic for SPIDER. In particular the layout of the diagnostic, together with the sensors distribution in the different components, the cables routing and the conditioning and acquisition cubicles are described. [ABSTRACT FROM AUTHOR]

In the Budker Institute, Novosibirsk, an ion source with arc-discharge plasma box has been developed in the recent years for application in thermonuclear devices for plasma diagnostics. Several modifications of the ion source were provided with extracted current ranging from 1 to 7 A and pulse duration of up to 4 s. Initially, the arc-discharge plasma box with cold cathode was used, with which pulse duration is limited to 2 s by the cathode overheating and sputtering in local arc spots. Recently, a directly heated LaB6 electron emitter was employed instead, which has extended lifetime compared to the cold cathode. In the paper, characteristics of the beam produced with both arrangements of the plasma box are presented. [ABSTRACT FROM AUTHOR]

A joint research and development effort whose ultimate goal is to develop steady-state intense ion sources to meet the needs of the two energy extremes of ion implanters (mega-electron-volt and of hundreds of electron-volt) has been in progress for the past two years. Present day high-energy ion implanters utilize low charge state (usually single charge) ion sources in combination with rf accelerators. Usually, a MeV linear accelerator is used for acceleration of a few milliamperes. It is desirable to have instead an intense, high charge state ion source on a relatively low-energy platform (dc acceleration) to generate high-energy ion beams for implantation. This endeavor has already resulted in very high steady-state output currents of higher charge states antimony and phosphorous ions. Low-energy ion implantation is performed presently by decelerating high-energy extracted ions. Consequently, output currents are low due to space charge problems. Contamination is also a problem due to gases and plasmas employed to mitigate the space charge issues. Our efforts involve molecular ions and a plasmaless/gasless deceleration method. A program overview is presented in this article. Although source specifics are described in accompanying papers, only this article contains our most recent results. [ABSTRACT FROM AUTHOR]

Atomic reaction models provide the link by which quantitative diagnostic comments on plasma behavior and parameters may be made from spectral observations of emission by ions in the plasma. This paper reviews progress in this area with emphasis on impurity species in magnetic confinement fusion plasmas. A systematic approach based on generalized collisional-radiative theory is adopted and items discussed include spectroscopy of edge and divertor environments, beam emission, and charge exchange spectroscopy. Case studies are based on experience at the JET Joint European Torus Experiment. [ABSTRACT FROM AUTHOR]

It is shown that a significant increase in the consistency of charge exchange spectroscopy and xray spectroscopy data for central ion temperature and plasma rotation is obtained when allowance is made for the following: (i) The charge exchange cross-section dependence on the impact energy of the neutral beam atoms in the frame-of-reference of the C[sup +6] a nuclei. In this paper we have experimentally verified the predicted cross-section effects on plasma rotation measurements using charge exchange spectroscopy by comparing to passive x-ray spectroscopy. The effect increases with lighter species, It should be emphasized that this effect is important for the rotation measurements only, while for the ion temperature measurements the effect is small compared to other error sources. (ii) The precise position of the radiating ion shell in line-of-sight averaged measurements using x-ray spectroscopy. For high-temperature plasmas with broad emission profiles the uncertainty in central ion temperature is reduced from up to 60% to the order of 20%. [ABSTRACT FROM AUTHOR]

Tandem mirrors control the axial variation of the plasma potential to create electrostatic "plugs" that improve the axial confinement of central cell ions and, in a thermal barrier tandem mirror, control the electron axial heat flow. Measurements of the spatial and temporal variations of the plasma potential are, therefore, important to the understanding of confinement in a tandem mirror. In this paper we discuss potential formation in a thermal barrier tandem mirror and examine the diagnostics and data obtained on the TMX-U device, including measurements of the thermal barrier potential profile using a diagnostic neutral beam and charged-particle energy spectroscopy. We then describe the heavy ion-beam probe and other new plasma potential diagnostics that are under development for TMX-U and MFTF-B. [ABSTRACT FROM AUTHOR]

The paper presents the results of tests of a new compact two-stage bulk gas plasma gun. The plasma gun is based on a nonself-sustained gas discharge with an electron emitter based on a discharge with a self-heating hollow cathode. The operating characteristics of the plasma gun are investigated. The discharge system makes it possible to produce uniform and stable gas plasma in the dc mode with a plasma density up to 3×109 cm-3 at an operating gas pressure in the vacuum chamber of less than 2×10-2 Pa. The device features high power efficiency, design simplicity, and compactness. [ABSTRACT FROM AUTHOR]

In burning plasma fusion devices, fast ion transport plays a central role in the performances of the machines. Moreover the losses of energetic particles might cause severe damages on plasma facing components. Therefore real time measurements of fast ion transport would provide valuable information for safe and reliable plasma operations. In this paper, we examine the feasibility of a monitoring system based on active charge exchange recombination spectroscopy making use of the 0.5 MeV/amu ITER heating neutral beams for detecting fast 4He+2 (alphas) particles in ITER plasmas. There are two time scales relevant to fast ion dynamics: the first is the slowing down time of the distribution function which is of the order of 1 s, and the second is the time scale of burstlike transport events such as collective Alfvén mode excitations, which—for typical ITER plasma parameters—can be as low as 0.2–1 ms. To detect such fast events a broadband high-throughput spectrometer is needed, while for the reconstruction of the alpha velocity distribution function a higher resolution spectrometer and longer integration time are necessary. To monitor a spatial redistribution of fast particles due to the propagation of the instability, it is proposed to use a limited number of spatial channels, looking at the charge exchange He II spectra induced by the heating beams, whose energy matches the slowing down energies of fast particles. The proposal is to share the motional stark effect periscope on equatorial port 3 [A. Malaquias et al., Rev. Sci. Instrum. 75, 3393 (2004)] adding additional fibers and suitable instruments. A signal to noise ratio of 5 could be achieved with a spatial resolution of a/15 and a time resolution of 5 ms, in a broad spectral band of 100 Å, corresponding to the spectral broadening of the line emitted by alpha particles with energies ΔE<=1.5 MeV. Fast H and D ion populations created by heating neutral beam or ion cyclotron resonance heating are expected to produce significantly lower charge exchange signal levels and can only be monitored on substantially longer time scales as it is expected because of the strong energy difference with respect to the heating neutral beam and the consequently low charge exchange cross sections. [ABSTRACT FROM AUTHOR]