摘要:

This paper summarizes the results from activation measurements of the limiter and the rf antenna in Alcator C‐MOD. The measurements were taken after the run period from May to October of 1993, during which hydrogen and deuterium discharges were studied. We conclude that bremsstrahlung photons generated by runaway electrons striking these materials induced most of the high threshold activation reactions. This means that electrons with energies higher than 10 MeV must have been generated in runaway discharges. ©1995 American Institute of Physics. 

ISSN:0034-6748    

DOI:10.1063/1.1146214

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Measurement of the global neutron production from the Alcator C‐Mod tokamak has been done for all experimental operation in deuterium, which commenced in August 1993. Up to 3×1012neutrons/s have been measured for diverse plasmas, including high current (1 MA), pellet injected, and rf heated discharges. Measurements during the initial run period were obtained using two sets of neutron detectors housed in polyethylene loaded moderator stations. Two more moderator stations containing additional neutron detectors have been obtained from LLNL and have been installed in the Alcator C‐Mod experimental cell. The system has been calibrated using Cf252placed at discrete points inside the Alcator C‐Mod vacuum vessel. This paper presents a description of the diagnostic, followed by details of the calibration method and results. A discussion of the derivation of ion temperature from the global measurements is included with first results from the integrated system. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146215

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We are developing an advanced electronic charged‐particle spectrometer (a magnetic/CCD system) for ICF &rgr;Rmeasurements. Knock‐on and other charged fusion products are bent by a magnetic field (about 1 T) in order to avoid line‐of‐sight x rays from directly impinging on the detector. The detector itself is a stack of four charge coupled devices (CCDs) sandwiched between ‘‘ranging filters’’. To avoid blooming effects in the CCDs, we plan to use only ‘‘thinned’’ CCDs, for which each element is ∼20 &mgr;m thick. (The CCD is supported by a silicon substrate of thickness ∼200 &mgr;m.) The CCDs are sandwiched between four aluminum filters which have two functions. The first filter reduces the background by completely ranging out select charged particles, such as 3.5 MeV &agr;’s (range &bartil;13 &mgr;m). Also, the first filter, with a thickness ∼50 &mgr;m, severely attenuates scattered soft x rays and visible light. The following three filters are each ∼300 &mgr;m. The total thickness of these filters and CCDs (with support substrate) are about 2000 &mgr;m, a thickness which completely stops energetic protons up to &bartil; 15 MeV. Equally important, the next three ranging filters downshift the particle energy, and this is reflected in increased energy deposition in the CCD (sincedE/dx∼1/E, whereEis the kinetic energy). With this spectrometer, a charged particle experiences four separate interactions with the CCDs and ranging filters: this allows the incident particle energy to be overdetermined and the particle to be uniquely identified. Furthermore, because the CCD has small picture elements (∼ 20 &mgr;m), pulse pileup can be avoided. A crucial tool in the development of this spectrometer is the MIT Cockcroft–Walton fusion product generator. This generator will be used to test and validate design concepts, study energetic particle trajectories through the magnetic field and through the detector stack, and to test and absolutely calibrate the response of this spectrometer to a variety of 0.5–15 MeV charged particles. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146216

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Fast‐response piezoelectric stress gauges are potentially useful in a number of plasma physics diagnostic applications, but have received only limited development in this direction. Principal applications include the measurement of pulsed photon, electron, ion,b)and neutral beam power, and magnetic pressure.c)We will discuss the use of X‐cut quartz and PVDF piezoelectric polymer stress gauges for measurement of ion power density on ion diode experiments. In our present work on the PBFA accelerator, we are attempting to quantify the ion and neutral particle flux in a parasitic beam which limits power coupling to the primary ion beam for light ion ICF experiments. Stress gauge data and hydrocode calculations related to this problem will be presented. ©1995 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146152

出版商:AIP    

年代:1995

数据来源: AIP