摘要:

A simple streaked slit diagnostic was developed to record resonance line emission from the plasmas used to produce Ne‐like nickel and Ni‐like silver X‐ray lasing. A Kentech streak camera with a 500 &mgr;m wide horizontal timing slit viewing the plasma transversely with a space resolving slit of width 270 &mgr;m positioned normal to the timing slit to give spatial resolution along the line focus length. An estimate of the duration of X‐ray laser gain is obtained by temporally resolving resonance line emission from states near in energy to the upper lasing level. The emission duration was measured to be 33 – 40 ps for Ni and 19 – 22 ps for Ag. We may expect the duration of this emission to be an upper bound on the gain duration. The travelling wave velocity at the leading edge of the main pulse was measured to be close to the speed of light. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1520990

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

We report new results using the LLNL COMET laser to evaluate the effectiveness of different target architectures to improve the output and characteristics of the transient x‐ray laser scheme. Surprising observations were found when the laser line focus irradiating a single slab Cr or Fe target was divided into two or three distinct plasma column sections with millimeter scale gaps between each plasma. The Ne‐like 3p1S0→ 3s1P128.5 nm and 25.5 nm x‐ray laser lines, for Cr and Fe, respectively, were improved in beam divergence, by 2 – 3 times, and peak intensity, by up to one order of magnitude, when compared with a single plasma column of the same length or longer. This was contrary to expectations since these large‐scale inhomogeneities introduced along the plasma, as well as attenuation from the cold plasma at the end of each section, would be detrimental to the x‐ray propagation and amplification. Instead an injector‐amplifier (IA) type process appears to be at work where the plasma gaps may be beneficially modifying the ray propagation and coupling through the high Ne‐like ion gain regions. We present results showing the output of the amplifier stage with increasing length for the IA targets together with beam deflection and divergence measurements. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1520991

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

A measurement of the time‐resolved emission of transient X‐ray laser pulses is described. An ultra‐fast X‐UV streak camera set at the focal plane of a flat field Spectrometer was used to obtain the temporal evolution of X‐UV spectra of Ni‐like Ag and Ne‐like Ni plasmas in a small wavelength range covering the lasing lines. The total time resolution of the device was of 1,1 ps. The FWHM duration of the X‐ray laser pulse was measured to be 3.5 ps for Ni‐like Ag (3d94d(3/2,3/2)J=0→3d94p(5/2,3/2)J=1, &lgr;=13.9 nm) and 13±2 ps for Ne‐like Ni (2p53p(1/2,1/2)J=0→2p53s(1/2,1/2)J=1, &lgr;=23.1 nm). Lasing signal was also observed on the 4f‐4d laser line (&lgr;=16nm) in Ni‐like Ag,, in both time‐integrated and time‐resolved spectra. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1520992

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

We present results of experimental studies on transient gain soft x‐ray lasers with a picosecond‐laser‐irradiated gas puff target. The target in a form of an elongated gas sheet is formed by pulsed injection of gas through a slit nozzle using a high‐pressure electromagnetic valve developed and characterized at the Institute of Optoelectronics. The x‐ray laser experiments were performed at the Lawrence Livermore National Laboratory using the tabletop Compact Multipulse Terawatt (COMET) laser to irradiate argon, krypton or xenon gas puff targets. Soft x‐ray lasing in neon‐like argon on the 3p‐3stransition at 46.9 nm and the 3d‐3ptransition at 45.1 nm have been demonstrated, however, no amplification for nickel‐like krypton or xenon was observed. Results of the experiments are presented and discussed. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1520993

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

The saturated operation of a soft X‐ray laser in Ni‐like Ag at 13.9 nm pumped by a single profiled picosecond laser pulse with the length of 6 ps has been demonstrated. The pump energy of 3 J used for lasing in this scheme is equal to half of the minimum energy applied in the previously reported experiments. Small signal gain coefficient as high as 33 cm−1has been estimated from the data. The influence of the pump beam characteristics on the output is discussed as well. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1520994

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

By traveling wave irradiation with a compact, 2‐beam, 1‐ps, 20‐J CPA Nd‐glass laser dedicated to x‐ray laser research, saturated amplification has been demonstrated in Ni‐like Ag at 13.9 nm and Ni‐like Sn at 12.0 nm. High gain amplification has been also obtained in Ni‐like La at 8.8 nm and with gaseous targets in Ne‐like Ar at 46.9 nm and Ni‐like Xe at 9.98 nm. Generation of highly coherent x‐ray laser is planned by injection seeding of the plasma amplifier. The newly developed 340‐TW Ti‐sapphire laser may enable generating exceedingly high power x‐ray radiation which will be useful for pumping inner‐shell ionization x‐ray lasers. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1520995

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

We observed strong amplification of the transition of 4d4p,J= 0 1 (the transition from (3d3/2, 4d3/2)0to (3d3/2, 4p1/2)1) of the Ni‐like lanthanum (La) ions at a wavelength of 8.8 nm pumped by a compact CPA Nd:Glass laser light at a wavelength of 1.053 &mgr;m with a pumping energy of 18 J. The experimental gain coefficient and the achieved gain‐length product was 14.5 cm−1and 7.7, respectively. In this experiment, the pumping laser pulse consisted of a pre‐pulse with a duration of 200 ps and a 7ps‐duration main pulse, separated by 250 ps. A hydrodynamics simulation coupled with a collisional‐radiative model showed that the present experimental condition generated a pre‐formed plasma with small volume and made it possible by the main pulse to heat the high density region effectively. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1520996

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Numerical codes predict for transient x‐ray lasers (XRL) very high picosecond duration gains [e.g. 1] that are restricted in space to several microns at FWHM. XRL beam propagation in plasma is vital for estimation of the effective gain at the plasma output. In this paper, beam propagation in transient plasmas is analytically studied. General 2‐D formulae are developed for beams in electron density gradient media, including those with the exponential profile that describes the plasma created from a solid target. The gradient is predicted to potentially limit the amplification length within the maximum gain to <2.6 mm in standard experiments. The result given by the analytical model is confirmed by numerical ray tracing of XRL beams within an amplifying medium as it is defined by the full numerical simulation using the EHYBRID code. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1520997

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Recent high temporal resolution Ni‐like x‐ray laser (XRL) experiments [1] have yielded important insights into the output characteristics of picosecond pumped XRL’s and the shortest XRL pulse was demonstrated. However, important issues were raised that require to enhance our understanding of plasma and population dynamics, namely (a) short pulse duration, (b) XRL pulse occurring before the peak of continuum emission and (c) the role of (over‐)ionization. A numerical study of the Ni‐like transient silver XRL has therefore been undertaken to complement our experimental results. High gain coefficients existing with picosecond lifetimes and restricted in space (∼5 &mgr;m FWHM) are predicted, which is consistent with short XRL durations experimentally observed. The simulations suggest that the gain is cut‐off by fast over‐ionization of Ni‐like ions. The late onset of the continuum emission relative to the temporal peak of the XRL output (as observed experimentally) is explained as a signature of a thermal conductivity wave propagating toward the super‐critical density region close to the target surface. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1520998

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

A survey of the Max Born Institute (MBI) activities in the field of X‐ray lasers (XRLs) is presented. The main interest is focused on the transient soft X‐ray lasers. Additionally, much work is put to look for new, efficient, compact (table‐top) pumping schemes with a prospect to be applied in practice. The current state of the research and the plans for the future are described as well. © 2002 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1520999

出版商:AIP    

年代:1902

数据来源: AIP