Part b.

Exercise 1. Read and translate the text.

Plasma.

The field of physics which is connected with highly io­nised gases is known to be plasma physics. A gas compo­sed of almost equal number of positive and negative free charges, namely, positive ions and electrons is culled a plasma.

Plasma differs greatly from ordinary gases because of its being composed of charged particles. Hence, one may consider it to be the fourth state of matter.

Ionised gases are found naturally in the universe except on the surface of cold planets, such as the earth.

In recent years interest in plasma physics has grown because plasma is applied in electrical engineering and space research, as well as in the development of the ther­monuclear power generation.

As to practical applications of ionised gases, they de­pend on the fact that when ionised, the gas will conduct electricity. Such ionisation is produced rapidly in case a critical electric field is exceeded.

In addition to it plasma can be applied in lighting where collisions between atoms and electrons provide a method of converting electric energy into light.

Of no less importance is the application of plasma in the direct conversion of kinetic energy into electric ener­gy. An attempt to force a moving conductor through a magnetic field gives rise to an electric field. If suitable contacts are provided it can drive a current. Provided the conductor takes the form of a long wire wound on an ar­mature, it is a dynamo. But if a conductor is an ionised gas or flame flowing between electrodes instead of the long wire it is a magneto-hydrodynamic generator (MHD). Power should be obtained from a high tempera­ture gas by means of this generator.

In order to understand its importance let's consider an elementary MHD generator. Heated gas flows through the channel across the magnetic field lines which arc perpendicular to the plane of the drawing. A vertical induced EMF causes current to flow between the electrodes and through the load. Thus, as the gas expands through the channel, it does work on the magnetic field and produces electric power.

The primary energy source for heating the gas may be either ordinary combustion or fission. For a power station using combustion, the efficiency of the cycle is limited by the temperature at which rotating machines can operate. An MHD generator offers the advantage that energy can be obtained from the gas at temperatures above those which can be withstood by solids. The chamber walls may be cooled below the gas temperature, as is the case in a rocket. On the other hand, the MHD generator can with­stand the upper temperature range. It means from the combustion temperature to that at which the conductivity becomes too low for the interaction with the magnetic field. At this temperature there is still some heat energy in the gas and that energy is obtained due to a steam cycle.

For the case of a fission reactor, used as the primary energy source, it is possible to develop solid fuel elemen­ts. These elements can have a long life time at temperatu­res greater than those at which rotating machines can ope­rate. Thus, the upper cycle temperature can be raised by means of the MHD generator.

Exercise 2. Read the following words. Translate them make up sentences using the words.

physics, highly, ionise, surface, earth, research, thermonuclear, hydrodynamic, primary, efficiency, advantage, chamber.

Exercise 3. Give different Ukrainian meanings of the following words.

Primary engineering, lighting, force, field, provide, wise, conduct, fuel, develop.

Exercise 4. Answer the questions:

1. What field of physics is called plasma physics?

2. What do we call plasma?

3. In what does plasma differ from ordinary gases?

4. Where are ionised gases found?

5. Why has interest in plasma grown in recent years?

6. Under what conditions will the gas conduct electricity?

7. Where can plasma be applied?

8. What is an MHD generator?

9. What is the advantage of an MHD generator?

10. What is the difference between a dynamo and MHD generator?

Exercise 5. Translate the sentences into Ukrainian.

1. Plasma phenomenon has also been observed both in interstellar space and in the ionised gases of the earth’s outer atmosphere.

2. In order to obtain a physical picture of plasma, it is necessary to consider its behaviour from different aspects.

3. In addition to the direct current devices, plasma electric alternators are also developed.

4. As to plasma properties and applications they are dealt with in the next article.

5. Interest in plasma physics is very great because of its being applied in electrical engineering and space research.

6. Naturally occurring plasma exist in the sun, in lightning as well as in the ionosphere.

Exercise 6. Form adverbs using the following adjectives and translate them.

high, great, rapid, near, short, late, herd, ordinary, efficient, electric.

Exercise 7. Translate and compare the following words and phrases.

Through-though; for-four; at rest-the rest of; this - thus; little-a little; because -because of; latter-later; some-the some.

Exercise 8. Annotate the text using the phrases.

The subject of this text is … ; The author described … ; The purpose of this article is … ; It is pointed out that … ; The author tells us about … ; The text also discusses … ; The next part of the text is devoted to … ; Further the author describes … etc.