Chris Spencer edited Data Analysis.tex  about 10 years ago

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\section{Data Analysis}  The measurements have been plotted in figures 3 through 5. Figure 3 shows waves launched 1.2 $\mu$s after being triggered. First waves are seen propagating towards density minimum, where the duct is located. Figure 4 shows measurements taken 2.28 $\mu$s after being triggered, were the wavefront is evident to be propagating away from duct position. The limit at which the wave will propagate towards the density maximum is when \[\omega \geq >  \frac{\omega_{ce}}{2}\] where $\omega_{ce} = \frac{qB}{m_e}$. Solving for the magnetic field and plugging in frequency $f = 2\pi\omega$: \[B_{max}=\frac{4\pi m_e f}{q}\]   Plugging in $f$ = 110 MHz, then $B_{max}$ = 78.6 Gauss. Looking at figure 2, the magnetic field measurements next to the source (position 2) were measured to be 79.4 Gauss, above the maximum magnetic field.  Since the magnetic field an that region was higher than critical magnetic field for 110 MHz, its reasonable to assume the waves will propagate towards the density minimum where the duct is located, as can be seen in the measurements. In figure 4, after a micro second, wave fronts are seen traveling towards the density maximum. Magnetic fields measured further away from the source than position 2 are less than $B_{max}$, where $\omega$ > $\frac{\omega_{ce}}{2}$. Plotting magnetic field magnitudes for x and y, as shown in figure 5, it can be seen that the plasma is right-hand elliptically polarized. This would suggest that the wave front is not necessarily travelling parallel to the field lines, but is moving at an angle, which can be seen in figures 3 and 4.