  X-rays are a valuable diagnostic tool for the study of high energy
accelerated electrons. Bremsstrahlung X-rays produced by, and directly related
to, high energy electrons accelerated during a flare, provide a powerful
diagnostic tool for determining both the properties of the accelerated electron
distribution, and of the flaring coronal and chromospheric plasmas. This thesis
is specifically concerned with the study of spatial, spectral and polarization
properties of solar flare X-ray sources via both modelling and X-ray
observations using the Ramaty High Energy Solar Spectroscopic Imager (RHESSI).
Firstly, a new model is presented, accounting for finite temperature, pitch
angle scattering and initial pitch angle injection. This is developed to
accurately infer the properties of the acceleration region from the
observations of dense coronal X-ray sources. Moreover, examining how the
spatial properties of dense coronal X-ray sources change in time, interesting
trends in length, width, position, number density and thermal pressure are
found and the possible causes for such changes are discussed. Further analysis
of data in combination with the modelling of X-ray transport in the
photosphere, allows changes in X-ray source positions and sizes due to the
X-ray albedo effect to be deduced. Finally, it is shown, for the first time,
how the presence of a photospheric X-ray albedo component produces a spatially
resolvable polarization pattern across a hard X-ray (HXR) source. It is
demonstrated how changes in the degree and direction of polarization across a
single HXR source can be used to determine the anisotropy of the radiating
electron distribution.
