Abstract. Different methods for assessing evapotranspiration (ET) can significantly affect the performance of land surface models in portraying soil water dynamics and ET partitioning. An accurate understanding of the impact a method has is crucial to determining the effectiveness of an irrigation scheme. Two ET methods are discussed: one is based on reference crop evapotranspiration (ET 0 ) theory, uses leaf area index (LAI) for partitioning into soil evaporation and transpiration, and is denoted as the ET ind method; the other is a one-step calculation of actual soil evaporation and potential transpiration by incorporating canopy minimum resistance and actual soil resistance into the Penman-Monteith model, and is denoted as the ET dir method. In this study, a soil water model, considering the coupled transfer of water, vapor, and heat in the soil, was used to investigate how different ET methods could affect the calculation of the soil water dynamics and ET partitioning in a crop field. Results indicate that for two different ET methods this model varied concerning the simulation of soil water content and crop evapotranspiration components, but the simulation of soil temperature agreed well with lysimeter observations, considering aerodynamic and surface resistance terms improved the ET dir method regarding simulating soil evaporation, especially after irrigation. Furthermore, the results of different crop growth scenarios indicate that the uncertainty in LAI played an important role in estimating the relative transpiration and evaporation fraction. The impact of maximum rooting depth and root growth rate on calculating ET components might increase in drying soil. The influence of maximum rooting depth was larger late in the growing season, while the influence of root growth rate dominated early in the growing season.

In this paper, we first achieve nanosecond-scale dissipative soliton resonance (DSR) generation in a thulium-doped double-clad fiber (TDF) laser with all-anomalous-dispersion regime, and also first scale the average power up to 100.4 W by employing only two stage TDF amplifiers, corresponding to gains of 19.3 and 14.4 dB, respectively. It is noted that both the fiber laser oscillator and the amplification system employ double-clad fiber as the gain medium for utilizing the advantages in high-gain-availability, high-power-handling and good-mode-quality-maintaining. DSR mode-locking of the TDF oscillator is realized by using a nonlinear optical loop mirror (NOLM), which exhibits all-fiber-format, high nonlinear and passive saturable absorption properties. The TDF oscillator can deliver rectangular-shape pulses with duration ranging from ~3.74 to ~72.19 ns while maintaining a nearly equal output peak power level of ~0.56 W, namely peak power clamping (PPC) effect. Comparatively, the two stage amplifiers can scale the seeding pulses to similar average power levels, but to dramatically different peak powers ranging from ~0.94 to ~18.1 kW depending on the durations. Our TDF master-oscillator-power-amplifier (MOPA) system can provide a high power 2-μm band all-fiber-format laser source both tunable in pulse duration and peak power.

Ultrafast fiber lasers with broad bandwidth and short pulse duration have a variety of applications, such as ultrafast time-resolved spectroscopy and supercontinuum generation. We report a simple and compact all-fiber thulium-doped femtosecond laser mode-locked by carbon nanotubes. The oscillator operates in slightly normal cavity dispersion at 0.055 ps2, and delivers 152 fs pulses with 52.8 nm bandwidth and 0.19 nJ pulse energy. This is the shortest pulse duration and the widest spectral width demonstrated from Tm-doped all-fiber lasers based on 1 or 2 dimensional nanomaterials, underscoring their growing potential as versatile saturable absorber materials.

We propose that most of the collisionless shocks in the Universe, for example, supernova remnant shocks, are produced because of the magnetic field generated by Weibel instability and its nonlinear process. In order to verify and validate the computational result confirming this theory, we are carrying out model experiments with intense lasers. We are going to make a collisionless counter-streaming plasma with intense laser ablation based on the scaling law to laser plasma with the particle-in-cell simulation resulting in Weibelmediated shock formation. Preliminary experimental data are shown. The photo-ionization and resultant non-LTE plasma physics are also very important subjects in astrophysics related to mainly compact objects, for example, black hole, neutron star and white dwarf. Planckian radiation with its temperature 80-100 eV has been produced in gold cavity with irradiation of intense lasers inside the cavity. The sample materials are irradiated by the radiation inside the cavity and absorption and self-emission spectra are observed and analyzed

X-ray ultraviolet absorption measurements of aluminum plasma at high temperature and high density are reported. A sample plasma was created by direct laser irradiation of a multilayered foil consisting of Au, CH, and Al. Observations were made using the method of self-backlighting spectroscopy. Simulations were performed with one-dimensional radiation-hydrodynamics code to compute the backlight profile as well as the time history of the density and temperature in the sample. By comparing the measured absorption spectra with detailed-term-accounting calculations at Te=120eV and ρ=0.1g∕cm3, it is found that the major spectral features predicted by calculations have been observed. Even better agreement between the experiment and the simulated absorption spectra was obtained by temporally averaging the radiation-hydrodynamics result over the backlight profile. This experiment shows that it is possible to measure high density and high temperature opacity by a laser-driven multilayer experiment.

We demonstrate an integrated all-fiber mid-infrared (mid-IR) supercontinuum (SC) source generated by a 1.95 μm master oscillator power amplifier system and a single-mode ZBLAN (ZrF 4 -BaF 2 -LaF 3 -AlF 3 -NaF) fiber. The maximum average output power is 10.67 W with spectral bandwidth covering from ∼1.9 to 4.1 μm. The single-mode ZBLAN fiber and silica fiber are thermal-spliced to enhance the robustness and practicability of the system. It is, to the best of our knowledge, the first high-power integrated compacted all-fiber mid-IR SC source based on thermal-spliced silica fiber and ZBLAN fiber. ©

Cherenkov radiation generated by a beam of electrons is theoretically investigated. In the case that the boundary effect is negligible, coherent Cherenkov radiation does not depend on the longitudinal bunch form of the electron beam, which is remarkably different from other kinds of coherent radiation like coherent transition radiation and coherent synchrotron radiation. The reason for this result is ascribed to the criterion of the emission of Cherenkov radiation. The angular distribution of coherent Cherenkov radiation is mainly determined by the transverse bunch form of the beam. The spectral intensity of incoherent Cherenkov radiation is proportional to the velocity distribution function of the electrons in the beams. Based on these results, some methods are suggested to study hot electrons with the measurement of Cherenkov radiation.

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