# Chapter 1: Introduction

1. What is plasma?
• ionized gas (short but incomplete)
• solid/liquid/gas + energy $$\rightarrow$$ PLASMA
• PLASMA
• fully ionized: 100% of atoms are ionized
• only consist ions & electrons
• partially ionized: fraction of atoms are ionized
• consist ions & Electrons & neutral atoms and molecules
2. Examples of plasmas
• sun, interstellar medium, lightning ......
3. Plasma temperature
• most behave classically $$\rightarrow$$ Boltzmann statistics
• distribution of particle speed follows Maxwell-Boltzmann distribution
• $$f(v)=4\pi v^2 n(\frac{m}{2\pi k_B T})^{\frac{3}{2}}\exp(-\frac{mv^2}{2k_B T})$$
• $$v_p=(\frac{2k_B T}{m})^{\frac{1}{2}}$$ (speed at the peak)
• $$v_{rms}=(\overline{v^2})^{\frac{1}{2}}=(\frac{3k_B T}{m})^{\frac{1}{2}}$$ (root mean square speed)
• • convert temperature $$K$$ into $$eV$$:
• $$=\frac{k_B T}{e}$$
• $$1.0eV=1.16\times 10^4 K$$
4. Debye Shielding
• • changed spheres electrostatically shielded
• shielding incomplete because charge particles in the high energy tail of the Maxwellian can escape
• Debye Length: $$\lambda_D=(\frac{\epsilon_0 k_B T}{ne^2})^{1/2}$$
• $$n$$ is the density at distance $$>>\lambda_D$$
5. Plasma Criteria
• macrosopic charge neutrality(quasineutrality)
• total postive charge = total negative charge
• must show collective behaviour
• electomagnetic forces dominate over normal hydrodynamics
• to quantify:
• $$L>>\lambda_D$$
• $$L$$ is plasma dimension
• the number in a Debye sphere more than 1
• $$N_D=\frac{4}{3}\pi \lambda_D^3 n_e>>1$$

# Chapter 7: Kinetic Theory

Plasma Physics Learning Notes
https://oybdooo.github.io/2023/07/28/Plasma-Physics-Learning-Notes/

OYBDOOO

2023年7月28日