The German Aerospace Centre carries out since many years studies on the flow and combustion of liquid jets expanding in a high pressure chamber through a single injector. For this study, liquid nitrogen has been injected into a pressurized test chamber filled with gaseous nitrogen at different test conditions. The behavior of the flow is well known on principal but the liquid zone, near the injector, is not accessible for the analysis using classical optical diagnostics. In order to be able to study this zone of the cryogenic jet, a new compact and pulsed (50 ns FHWM typical) X-ray source has been developed and utilized. During experiments carried out on the test bench M51 of the DLR, this soft X-ray flash energy, enable us to carry out radiography of the zone close to the injector (z/d < 10) for chamber pressures from 1.0 to 6.0 MPa and temperatures of the liquid nitrogen jet ranging from 100 to 130 K. The data and their Processing result in the possibility to obtain the various density profiles corresponding to injection conditions. The obtained results are compared with those collected by other methods (experimental and numerical) already used in the DLR.
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