SU1393034A1 - Polarimeter for plasma diagnosis - Google Patents

Abstract

The invention relates to the field of optics, in particular to devices for the diagnosis of plasma, and can be used dp measurement of the time variable angle of rotation of the polarization plane in the plasma. The purpose of the invention is poaching the measurement. Planarized light from the source of the probing signal 1, the passage along the magnetic field in groove 9, experiences a rotation of the plane of polarization at a certain angle. Then the light passes the quarter-wave plate 3 and hits the polarization divider 4, the wires of which form the angle of 45 ° with the direction of the main optical base of the quarter-wave plate 3. A difference of phases arises between the beams of light, the transmission through the polarizer and reflected from it, depending on the angle of rotation of the polarization plane. These beams are fed to the corresponding microwave detectors 5 and 6. The latter also receive radiation from the source of the heterodyne signal 2. As a result, the intermediate frequency signals appear at the outputs of the microwave detectors 5 and 6, the phase difference of which is equal to the double angle of rotation of the field plane. 3 pe. § (L

Description

with so

00

about co 4

The acquisition relates to the opl-T11KI field, in particular, to devices for the dylgiostika of pldma, and the beat test is used to measure the variable angle of the polarization plane of the plasma.

The purpose of the invention is to measure points.

FIG. I shows a block diagram of a field meter; in fig. Figures 2 and 3 show vector diagrams, illustrating the position of the vector of the probe and heterodyne signals at the points. in fig. one.

The device contains two sources of plane-polarized radiation: probing signal 1 and heterodyne signal 2, quarter-wave plate 3, polarization divider of rays 4, detectors 5 and 6, mixing detectors 7 and 8. The outputs of the detectors are the outputs of the entire device. The plasma volume 9 under study is located between the source 1 and the quarter-wave plate 3. The letters a and g in the diagram indicate points at which the position of the electrical vectors of the propagating signals is analyzed below.

Floor meter works as follows.

From the source 1, the plane-propagated wave propagates

 cosu) j, t, us, 0,

where X and y are the projections of the vector E onto

Axis Oh and Oh respectively

a is the amplitude of the floor; subscripts correspond to points in the diagram of FIG. 1 for which the electric field vector is written. After passing through the plasma, the polarization plane of the probe radiation is rotated by an angle rf, therefore

 cose (.cosu) ct

 sinoI-cosijOjt

After passing through the quarter-wave plate 3, the main optical axis of which is parallel to the axis Ox, component X acquires a phase shift of 90 relative to component y, the wave becomes polarized in an ellipse

HD cost / sinuJf-t

Vg-a Binet cosuvt

Simultaneously with the sound passing through the plasma, the sounding beam splitter 4 serves the heterodyne frequency signal s

 cosij t

where b is the amplitude of the floor;

Further transformation of the field vectors is illustrated by the diagrams of FIG. 2 and 3. The vectors corresponding to the points d (Fig. 2) and e (Fig. 3) are shown in solid lines; the vectors corresponding to the whig points are shown in dashed lines. In Figures 2 and 3, the coordinate system tfli is rotated to A5 with respect to the coordinate system xOu, while the wires of the polarization divider of rays 4 are directed along axis 0. The reflected probe and transmitted heterodyne signal arrive at point e (Fig. 2) :.

one

1I

- R- -V2

V2

G2

one

 (COOE (sinu) t-Binofcosu t) +

/ 2 + b.

The point (e) is covered by the probiry soundirutations and the reflected heterodyne signals (Fig. 3):

H 1- x, U. + 1- x V2 / 2

 - {a (co5v (-sinkij.t + sino (-cosaict) +/2

+ b COSLJrt.

Thanks to the effects of analyzers. Ditch 5 and 6, the wires of which are oriented along the Ox axis, at points g and 3 will be only one component. After the transformations we get

x sin (ui t-b: /) - t-b,

x sin (wjt-o /) + b cosoJrt.

The signals at the outputs of the mixing detectors 7 and 8 are

, cos (nt-K) (), Ug BjCos (nt-of).

where B and Bj are factors depending on signal levels and mixer characteristics.

Thus, in the proposed polarimeter, the rotation of the polarization plane in the plasma and the angle d leads to a change in the phase difference of the intermediate frequency signal by an amount. The latter can be measured by lime phase metering methods.

Claims (1)

Formula invented Polimeter for plasma diagnostics, containing ampoules of copolymerized, probe and heterodyne radiation located at the inputs of the polarization beam divider, - consequently installed analyzer and mixing detector at each of the outputs of the polarization beam divider, characterized in that, in order to improve measurement accuracy, it also contains a quarter-wave plate mounted on the optical axis of the beam probing radiation in front of the polarization beam splitter. FIG. one IT U9.J K / - () 091PL - "HtlX-, e 0M ".J