@misc{oai:repo.qst.go.jp:00072995,
 author = {Kakunaka, N. and John, C. and 岸本, 牧 and Matsumoto, Y. and 長谷川, 登 and 錦野, 将元 and Higashiguch, T. and Ejima, T. and Sunahara, A. and Nakajima, F. and Johzaki, T. and Endo, T. and Namba, S. and 岸本 牧 and 長谷川 登 and 錦野 将元},
 month = {Nov},
 note = {Water  window (WW) soft X-rays (wavelength 2.3 to 4.4  nm)  are  easily  absorbed  by  carbon  and  are  hardly absorbed by water around the living cells. Therefore, X-ray  microscopy  using  WW  soft  X-ray  is  expected  as  a technology  for  observing  nanometer  scale  structure  of living cells.  In order to obtain a high spatial resolution image with a soft X-ray microscope, a high intensity soft X-ray source is necessary, and usually high-power lasers of 10 J or more is indispensable. This is a major obstacle to spread and development of soft X-ray microscopes in medical and biological research fields. 
Recently, it has been found that when a gold target is irradiated with a commercial Nd:YAG laser (1064 nm, 7 ns, 1 J) under low-pressure nitrogen atmospheres up to 400  Pa,  Soft  X  rays  intensity  emitted  from  plasmas increase significantly. Accordingly, a compact and low-cost X-ray microscope can be expected. In this study, in order to generate hot dense plasmas emitting much bright X-ray radiation, picosecond lasers with 10-ps and 500-ps pulse durations were employed. Gas  fill circumstance  is  achieved  by  introducing  nitrogen  gas using  a  mass  flow  controller.  For  the  soft  X-ray measurement, a grazing incidence spectrometer (flat field grating of 2400 grooves / mm) with a toroidal focusing mirror is used. A pinhole camera with an aperture of 0-micron  in  diameter  is  also  installed  to  measure  two-dimensional  X-ray  imaging  (magnification  of  14×).  To block the out-of-band radiation, appropriate thin filters are inserted in the pinhole tube. 
In this presentation, we will also report the influence on nitrogen gas fill circumstances by using picosecond laser pulses., 2nd Asia-Pacific Conference on Plasma Physics (AAPPS-DPP2018)},
 title = {Water window soft X-ray emission from Au plasmas generated with a picosecond laser pulse},
 year = {2018}
}