XUV and X-ray Probing of Warm Dense Matter

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In this research we are seeking to further investigate a very interesting form of matter called 'warm dense matter' or WDM. This is a state of matter that is expected to be found, for example, in the cores of giant planets like Jupiter and Saturn and to a lesser extent the Earth. The matter is characterized by being at high density (sometimes above normal solid density) and at an elevated temperature ranging from 10,000K to well above 1 million degrees. This means that the pressure is enormous, reaching several million times atmospheric pressure. Under these conditions the matter is not expected to behave either like a normal solid or like a classical plasma. We will make samples of warm dense matter in a variety of ways. One of these involves using intense laser pulses to drive very strong shocks into solid samples, thus compressing and heating them. We will probe these samples with intense x-rays generated from another laser-plasma. This takes place on a timescale of less than a billionth of a second. The results will test the electronic structure of the matter under WDM conditions. In other types of experiment, we will heat solid foils with x-rays generated from laser-heated targets. This will raise the temperature of the solid matter to several thousand degrees. We will probe this matter with XUV radiation generated from gas-laser interactions using high harmonics of the initial laser wavelength. This will help to measure the degree to which XUV radiation is absorbed.