A method for measuring the temperature in a discharge with the aid of Jamin's interferometer

✍ Scribed by J.M.W Milatz; H.A Vreedenberg; J.W Braak

• Publisher: Elsevier Science
• Year: 1943
• Weight: 279 KB
• Volume: 10
• Category: Article
• ISSN: 0031-8914
• DOI: 10.1016/s0031-8914(43)90034-5

✦ Synopsis

The radial distribution of the temperature in the positive column of a discharge can be determined by measuring the displacement of the fringes, obtained with the aid of J a m i n's interferometer. This effect is so large that one can easily see the movement of the fringes by varying the current in the discharge-tube. It is shown, that the influence of curvature of the rays may be neglected. Some provisional results are compared with those of other methods. One of the advantages of the method is its high accuracy. § I. The experimental arrangement (fig. 1). A classical method for measuring the density of a homogeneous gas, which is present in a closed tube, ~s the determination of the refractive index with the aid of J a m i n's interferometer. The object of our investigation is to extend this method to the determination of the radial distribution of the density in the positive column of a discharge 1) 2). The temperature follows immediately from the measured density, as the pressure in the discharge-tube can be read on a mercury manometer.

In order to attain that every ray passes through a zone of equal density, the discharge-tube is traversed by a nearly parallel pencil ot rays.

An image ot a mercury lamp is produced on a diaphragm D with a diameter of .5 ram. D is near the focus of a concave mirror, which forms the pencil mentioned above. This pencil meets the first plate of the interferometer; the angle of incidence is 50 °. For this value the maximum distance between the beams a and b is reached.3), viz. 3.0 cm. The thickness of the plates is 4.0 cm. The front side of the plates --

433

--Physica X 28*