1. Physics 777 Plasma Physics and Magnetohydrodynamics (MHD) Instructor: Gregory Fleishman Lecture 12. Particle Acceleration 18 November 2008

2. Plan of the Lecture Elementary Concepts: DC Electric Fields and Adiabatic Motion Fermi Acceleration Stochastic Acceleration by Weak Turbulence Acceleration by a Shock Wave Acceleration by Strong Turbulence and Shock Ensemble Other Examples of Particle Acceleration

3. Section 1. Elementary concepts of particle acceleration How charged particles are being energized (accelerated)? Role of magnetic and electric fields. Adiabatic motion in a trap with moving walls. Regular acceleration/deceleration. Stochastic acceleration due to random wall motion.

4. Section 2. Fermi Acceleration. Credit: Cronin et al (1997); Livio Scarsi (2008) Challenge: acceleration mechanism must ensure a power-law spectrum; frequently – over many orders of magnitude.

6. BUT: how magnetic clouds can accelerate particles?

13. Section 3. Stochastic Acceleration by Weak Turbulence.

14. Section 4. Acceleration by a Shock Wave.

18. RECALL

26. Shock front in SNR 1006

27. Section 5. Acceleration by Strong Turbulence and Shock Ensemble Superbubbles in SMC

31. Turbulent acceleration in solar flares B 0 = 20G,  B x ~  B y ~ 20G,  B z ~ 100G Outer scales l x =l y =1km, l z =20km Sample trajectory magnetic field lines Credit: L. Vlahos

33. Section 6. Other Examples of Particle Acceleration

39. Section 7. Homework Complete written project report is due; no excuse.