Interferometria com laser de CO2 no TC-1 da UNICAMP

AUTOR(ES)
DATA DE PUBLICAÇÃO

1998

RESUMO

Three techniques for line integrated electron density measurement based on CO2 laser interferometry have been carried out on the compact toroid TC-1 UNICAMP, a theta-pinch that allows the generation and magnetic confinement of hidrogen plasma. In the first technique, it is used only one infrared detector for the counting of the interference fringes. The number of fringes displaced, when occurs the plasma implosion, is directly proportional to the variation of the electron density integrated along the laser beam path travelling through the plasma. The second technique makes use of one detector, like the first one, but the signal is now modulated by a moving mirror placed on the path of the reference laser beam, in order to add a "controlled noise" to this signal, thereby making the fringe counting easier. The main difficulty of the techniques above is the lack of information about the direction of the fringe displacement, when the signal from the detector reaches one of its extreme values. In order to eliminate this difficulty, a new technique is employed. There, two detectors are placed in a way that their signals have a phase difference of 90 degrees. This allows us to obtain the lacking information and, therefore, to observe the evolution of the plasma density in a more reliable way. It has been made measurements with the laser beam going through the plasma along its diameter and its axis. Using the third technique, it was also observed the density evolution for four word pressures. Finally, the results have beem compared with those obtained by Thomson scattering measurements

ASSUNTO(S)

laser plasma interferometria

ACESSO AO ARTIGO

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