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1. Explain similarities and differences in the physics of ion acoustic waves and neutral acoustic waves.
2. Explain the operation of an interferometer circuit for measuring the spatial properties of waves.
3. If a probe moves at an angle to the k-vector what is the measured wavelength?
4. Discuss mechanisms which produce an amplitude decay with distance from the exciter.
5. Discuss the refraction of ion acoustic waves in plasmas with density and temperature gradients.
6. How does the wavelength of an ion acoustic wave depend on wave amplitude?
7. Why does the observed wavelength of a grid-excited ion wave increase with applied voltage?
8. Why are ion acoustic waves strongly damped when the frequency approaches the ion plasma frequency?
9. What determines the resolution of short wavelength ion acoustic waves?
10. What is the effect of an ion drift on the propagation speed of ion acoustic waves?
11. How can one determine ion drifts from ion acoustic wave measurements?
12. Discuss the difference in the wave fronts excited by a grid small and large compared to the wavelength.
13. Suggest an exciter structure which focusses ion acoustic waves.
14. Discuss the radiation pattern from two "point" radiators separated by a distance d.
15. How can a beat phenomenon arise in the observed interferometer traces?
16. How can one measure the group velocity with an interferometer circuit?
17. What are the advantages/disadvantages of a narrowband amplifier in the interferometer circuit?
18. How can one produce standing ion acoustic waves?
19. How does an interferometer trace differ between standing and propagating waves?
20. How can one measure with an interferometer circuit the direction of wave propagation for undamped plane ion acoustic waves?
21. What is the peak electric field in an ion acoustic wave of wavelength lambda and amplitude delta n/n0? Why is there an electric field if ne=ni? Why is there no current in an ion acoustic wave?
22. Discuss the advantages/disadvantages of detecting ion acoustic waves with single probes, double probes, and emissive probes. What other methods exist to detect ion acoustic waves?
23. Discuss the mechanism of ion acoustic wave generation by a grid. What is the effect of the grid dc bias? When do nonlinear effects such as ion bursts take place?
24. What is the effect of primary electrons on the propagation of ion acoustic waves?
25. What is the dispersion of ion acoustic waves in a plasma with ions of different charge-to-mass ratio?
26. When does the ion sound speed coincide with the neutral sound speed? Can this be done experimentally?
27. More questions will follow.

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