Physics 777 Plasma Physics and Magnetohydrodynamics MHD Instructor

Physics 777 Plasma Physics and Magnetohydrodynamics (MHD) Instructor: Gregory Fleishman Lecture 5. Microscopic Emission Processes in the Plasma 07 October 2008

Plan of the Lecture • • • Vavilov-Cherenkov radiation Bremsstrahlung Diffusive radiations Magnetobremsstrahlung Transition radiation

Section 1. Vavilov-Cherenkov radiation (N. P. 1958) For simplicity:

Section 2. Bremsstrahlung

Coherent Bremsstrahlung

Section 3. Diffusive radiations Consider first the radiation in the presence of random magnetic field: Diffusive Synchrotron Radiation (DSR)

For power-law spectrum of random magnetic field we obtain:

Spectral asymptotes

Diffusive Radiation in Langmuir Waves (DRL) If

Section 4. Magnetobremsstrahlung

Asymptotic behavior

General case Cyclotron Emission

Section 5. Transition Radiation

Resonant Transition Radiation

Section 6. Homework • • Homework from Lecture 4. Written report topic (WRT) # 1. Assume stochastic acceleration at the loop top with a power-law spectrum of magnetic turbulence. Calculate the DSR spectrum from electrons with different non-relativistic energies. WRT # 2. Assume a power-law spectrum for Langmuir wave ensemble and some number (Ax 1033) of relativistic electrons with the Lorenz factor 10. Calculate the DRL spectrum. WRT # 3. Calculate synchrotron emission from warm and hot components of the interstellar medium. Calculate and plot these contribution together for different filling factors. WRT # 4. Assume sinusoidal oscillations of the transverse magnetic field component. Calculate modulation amplitude (or power), phase, and degree of polarization as a function of frequency. WRT # 5. Assume that the particle trapping at the Masuda source is provided by scattering of the electrons by magnetic inhomogeneities with a power-law spectrum. Calculate the DSR produced by the electrons generating the abovethe-loop-top hard X-ray emission (i. e. , take the electron spectrum from the corresponding papers). For all WRT: outline the introduction for the written report. Use Latex, e. g. , Ap. J style (preferable).