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Chapter#1: Introduction to Plasma

All S.Qs of Introduction to Plasma for the book Plasma Physics for BS/MSc Physics.

Q.1 Differentiate between hot and cold plasma.

Answer: Hot plasma: When the temperature of gas and plasma increased up to the level of ionization, hot plasma is produced. There will be no thermal mentions.

Cold plasma: if only the small fraction of gas molecules are ionized and electricity is used as energy source of the ionization then cold plasma is produced.

Q.2 Differentiate between magnetosphere and magnetopause.             

Answer: Magnetosphere: inner region or surface of compressed earth magnetic field in which solar wind is excluded is called as magnetosphere.

Magnetopause: conducting solar wind on earth. Magnetic field, compress the flow towards sun ward side if it is towards. Sunward side it would be roughly spherical, as if it would in anti-sunward side it would be cylindrical magneto.

Q.3 what is the relation between energy and temperature in plasma.

Answer: Temperature and average energy are very closely attached so, it is customary in plasma physics to give temperature in units of energy. For plasma;

    \[KT=1ev\]

    \[\because1ev=1.6\times{10}^{-19}J\]

    \[\because K=1.38\times{10}^{-23}\frac{J}{K}\]

    \[T=\frac{1ev}{K}\]

    \[T=\frac{1.6\times{10}^{-19}J}{1.38\times{10}^{-23}\frac{J}{K}}\]

    \[T=11.600K\]

The only gas which has a temperature of 11.600k in 1ev energy is called plasma.

Q.4 why life does not exist on plasma?

Answer: As temperature is raised the degree of ionization remains low until U_i is only a few times of KT. Further increase in temperature as of million of degrees temperature is increased then life cannot exist on plasma due to very high temperature.

Q.5 Write the expression of degree of ionization of a gas and explain it?

Answer: Degree of ionization =\ \frac{n_i}{\ n_n}

n_i  Ionized atom density

T= Temperature

n_n= Neutral atom density

K= Boltzmann constant

u_i= Ionization energy depends upon ( the amount of energy required to remove the outermost electron from atom)

Q.6 Differentiate between quasi neutral gas and quasi neutral plasma.

Answer:

Quasi neutral gas: The gas which have both positive and negative ions but overall is neutral is called quasi neutral gas.

Quasi neutral plasma: If plasma has positive and negative neutral ions then it is called as quasi neutral plasma.

Q.7 what is meant by stellar corona?

Answer: Stellar corona is defined as;

It is the stream of charged particles release from the upper atmosphere of sun called stellar corona.

Q.8 Define and explain Van Allen radiation belt?

Answer: A radiation belt refers to a layer in which charged and energetic particles trapped inside the earth magnetic field as execute by making complicated trajectories.

Q.9 Write the expression of average K.E in 3-D.

Answer:

    \[f\left(u,v,\ w\right)=\ \frac{3}{2}\ KT\]

General result is that equal \frac{1}{2}\ KT to per degree of force.

If KT = 2ev

    \[E_{av}=3ev\]

Q.10 In how many conditions plasma is ionized?

Answer: Plasma is ionized in two conditions.

  • Partially ionized: Partially ionized means the interacting atoms (ions and electrons) are left.
  • Fully ionized: Fully ionized means 100% ionized and no neutral atom left.

Q.11 Write down the assumptions of Debye shielding?

Answer: There are two following two assumptions of Debye shielding.

  • Maxwellian distribution: assume for simplicity that ion electron mass ratio is infinite so that ions does not move but from a uniform background of positive charge.
  • Mass of ion  mass of electron: \frac{mass\ of\ ions}{mass\ of\ electrons}=\ \frac{M}{m}\ \ \ \ \ \ \ \ M\gg m

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