Plasma-the 4th State of Matter

Topics: Magnetic field, Nuclear fusion, Fusion power Pages: 31 (10374 words) Published: November 25, 2010
1. Introduction
1.1 Basic Physics of Charged Particles Moving In a Magnetic Filed
1.2 The Lorentz Force
1.3 The Hall Effect
2. What Is Plasma?
2.1 What is it that distinguishes plasma from ordinary gases?
2.2 Commercial Applications
2.3 Waves in Plasma
3. Nuclear Fusion & Fusion Reactors
3.1 The Lawson’s Criterion
3.2 Magnetic Field Confinement
3.3 Inertial Confinement
4. TFTR & Its Contributions to Engineering
4.1 Transport
4.2 Fusion Power Production
4.3 Alpha-Particles Physics
5. Plasma & Space
5.1 Solar Prominences
5.2 Plasma Rockets
6. Conclusion
7. References

Table of Variables & Constants:

ε0Permittivity of free space
kCoulomb Constant, 9×109 N m2 C-2
τConfinement time
ωAngular frequency
eElectron charge
UPotential energy
BMagnetic field
EElectric field
TPeriod or Temperature

1. Introduction:

Until recently, looking at pictures similar to the one above had caused me to wonder; could this be a creation of some proficient artist, or the work of a powerful computer program? Honestly I never thought that this luminous phenomenon appearing as streamers of light, usually seen in the northern and southern regions of the globe, is what we have been taught in freshmen and sophomore physics about plasmas.

The aurora visible in this picture is thought to be formed by charged particles from the sun entering the earth’s magnetic field and stimulating molecules in the atmosphere. In one of the courses that I attended last semester, the instructor asked the class the following question; what is the greatest source of plasma noticeable to us? Among the seniors that were in that class, I, the first semester junior student, was the one who answers the question. Although I knew that our sun consists of plasma, I never really understood what the existence of plasma is all about. Fortunately, that class was concerned with direct energy conversion and its applications. Moreover, one of its essential topics was plasma and its essence in this field of studies.

For some reason that I cannot really figure out, the sun is a great source of inspiration for me. I get really astonished by any new fact that I learn about the sun. In this paper, I tend to present some of the phenomena that are of relevance to the study of plasma. Mainly, this paper is designated for the field of plasma confinement, which in turn requires an adequate knowledge of the physics of nuclear fusion.

1.1. Basic Physics Of Charged Particles Moving In A Magnetic Filed:

If a charged particle moves in a uniform magnetic field, it will be subjected to a magnetic force acting in a perpendicular sense to its velocity. Thus, the work done by this force is zero because the displacement of the particle is always perpendicular to the magnetic force. Therefore, a static magnetic field only changes the direction of the velocity and has no effect on the speed of the charged particle.

Considering the case of a positively charged particle, of magnitude q, moving in a uniform external magnetic field with an initial velocity of v, whose vector is perpendicular to the magnetic field directed into the paper. Obviously, the particle will undergo a circular motion perpendicular to the magnetic field as shown on the above figure.

If we are to get into more details, the magnetic force is at right angles to the velocity, and B, the magnetic field, and possesses a magnitude of qvB. While the force is deflecting the particle, the directions of v and the force, F, change continuously. Hence, the magnetic force in this case is a centripetal force. We can notice the effect of this force in keeping the speed at a constant value. If we wish to relate this magnetic force to the centripetal acceleration by Newton’s second law of motion: F=qvB= mv2/r

Hence, the radius of the path is directly proportional to the...
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