Hollinger, Reed, authorBargsten, Clayton, authorShlyaptsev, Vyacheslav N., authorKaymak, Vural, authorPukhov, Alexander, authorCapeluto, Maria Gabriela, authorWang, Shoujun, authorRockwood, Alex, authorWang, Yong, authorTownsend, Amanda, authorPrieto, Amy, authorStockton, Patrick, authorCurtis, Alden, authorRocca, Jorge J., authorOptical Society of America, publisher2020-04-282020-04-282017-10-27Reed Hollinger, Clayton Bargsten, Vyacheslav N. Shlyaptsev, Vural Kaymak, Alexander Pukhov, Maria Gabriela Capeluto, Shoujun Wang, Alex Rockwood, Yong Wang, Amanda Townsend, Amy Prieto, Patrick Stockton, Alden Curtis, and Jorge J. Rocca, "Efficient picosecond x-ray pulse generation from plasmas in the radiation dominated regime," Optica 4, 1344-1349 https://doi.org/10.1364/OPTICA.4.001344(2017)https://hdl.handle.net/10217/206009The efficient conversion of optical laser light into bright ultrafast x-ray pulses in laser created plasmas is of high interest for dense plasma physics studies, material science, and other fields. However, the rapid hydrodynamic expansion that cools hot plasmas has limited the x-ray conversion efficiency (CE) to 1% or less. Here we demonstrate more than one order of magnitude increase in picosecond x-ray CE by tailoring near solid density plasmas to achieve a large radiative to hydrodynamic energy loss rate ratio, leading into a radiation loss dominated plasma regime. A record 20% CE into hν > 1 keV photons was measured in arrays of large aspect ratio Au nanowires heated to keV temperatures with ultrahigh contrast femtosecond laser pulses of relativistic intensity. The potential of these bright ultrafast x-ray point sources for table-top imaging is illustrated with single shot flash radiographs obtained using low laser pulse energy. These results will enable the deployment of brighter laser driven x-ray sources at both compact andlarge laser facilities.born digitalarticleseng©2018 Optical Society of America. Under the terms of the OSA Open Access Publishing Agreement. Biomedical Optics Express, Optica, Optical Materials Express, Optics Express, and OSA Continuum are all gold open access journals. As a result of the authors paying an article processing charge (APC), all content published in these journals is freely available.Copyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.laser lightlaser materialslaser plasmaspulse generationradiative processesx ray lasersTexthttps://doi.org/10.1364/OPTICA.4.001344