Time-integrated spectra and time-resolved spectra (20 ns resolution) of nitrogen discharge plasma radiation were recorded and analyzed. Plasma was created by a 70 kA, 29 ns rise-time current pulse flowing through a 5 mm inner diameter, 224 mm long capillary filled with nitrogen to initial pressure ∼0.1 ÷ 1 kPa. Spectra were captured in the wavelength range 8.3 ÷ 14 nm. This spectral region contains nitrogen Balmer series lines including potentially lasing NVII 2 – 3 transition<sup>1</sup>. Spectral lines were identified using the NIST database and the FLY kinetic code. Together with spectra the capillary current was measured. Due to the low inductance design of the driver, the pinch is observable directly from the measured current. 13.38 nm NVII 2 – 3 line was observed in gated, and also in time-integrated spectra for currents <60 kA. For higher gas-filling pressure also other Balmer series lines were observed.
XUV radiation from nitrogen filled capillary discharge plasma was diagnosed using a 10<sup>4</sup> grooves/mm SiNx free-standing
transmission grating. The resolution bandwidth of 0.3 nm was achieved. Time dependence of 13.4 nm line
emitted power was recorded by photomultiplier in order to verify inherence of resonant radiation emission corresponding
to NVII 2-3 laser transition. An increase of emitted power is expected during the pinch decay caused by recombination
processes. We report here results obtained with 90 mm long capillary discharge supplied by a current pulse with
maximum amplitude of 50kA and quarter-period of 80 ns. This high-current pulse was generated by a 1.5 ohm water line
high-voltage generator which is used for underwater wire explosion experiments and which was adjusted for capillary
discharge design using results of PSPICE simulations. Initial nitrogen pressures were varied in the range of 20 ÷ 500 Pa.
MHD and kinetic simulations of the discharge plasma were performed and compared with experimental data.
Simulations were performed with presumption of wall ablation. The capillary wall and electrodes material emission lines
were also identified in measured spectra.
Thin films of hydroxyapatite, hydroxyapatite doped with silver and thin diamond like carbon layers were prepared using
KrF excimer laser deposition. Tooth prostheses, textile blood vessels and artificial heart valves were covered and tested.
Examples of physical tests, and in vitro and in vivo analysis using minipigs and sheep are presented.
We report new results of evaluated gain for 13.38 nm radiation created due to the inversion population on the Balmer
alpha transition of hydrogen-like nitrogen. Recombination pumping in non-equilibrium plasma during the capillary pinch
decay is judged. Quantitative analysis is performed in four-dimensional region of optional parameters chosen in
accordance with available experimental devices: current slope dI/dt<sub>|t=0</sub> (0.9-3.0 10<sup>12</sup> A/s), current peak value Imax (50-100 kA), capillary radius R<sub>0</sub> (0.16-0.25 cm) and filling atom density N<sub>0</sub> (1.0-6.0 10<sup>17</sup> cm<sup>-3</sup>). Requirements on the current
pulse shape are stated. Diameter of the created active medium is estimated.
Pinching capillary discharge in nitrogen is investigated for the purpose of development of laser recombination pumping. An apparatus, previously realized for argon capillary laser pumping, was used to understand details of pinching mechanism and emission characteristics for capillary filled by nitrogen. Time dependences of radiation intensities emitted in the wavelength range 1.9 - 2.5 nm and time integrated in the spectral range 10 - 20 nm were measured under various pressures. A computer model is used to describe the pinch dynamics and to estimate the radiation characteristics. EUV reflection grating spectrometer coupled to BI CCD camera and filtered PIN diode were used for time integrated and time resolved spectral measurements respectively. The measured profiles of radiation intensities are compared with the computer simulations of time dependences of selected energy level populations that correspond to the hydrogen- and helium- like ion line emission in the detected spectral range. Complex method for spectral image restoration was developed.
Basic information about Faculty of Biomedical Engineering CTU will be given. This new one faculty is a part of Czech Technical University in Prague since 2005. The 5 - year study (bachelour and magisterian) is oriented on the education of student in bioengineering. One of the goal of the FBME CTU is the education of students in optics, biophotonics, lasers and in applications of optics in biomedicine and biology. The details of training and research activities will be given.
In this paper our new capillary discharge device built for the soft x-ray laser studies is described and the first experimental results obtained from electrical, optical and UV diagnostics together with code simulations are presented.
Transmyocardial laser revascularization was fount to be a new emerging technique for the treatment of end-stage coronary artery diseases. In our study, a comparison has been made of mid-IR solid-state laser radiation interaction with a myocardium tissue. For this purpose, the Tm:YAG, CTH:YAG and Er:YAG laser systems were designed, constructed and used for the interaction experiments. The ablation coefficients were measured to be 3 mm/J for Tm:YAG; 0.03 mm/J for CTH:YAG, and 10.5 mm/J for Er:YAG interacting laser radiation. From the histological examination follows that the channels ablated by Er:YAG laser radiation are without any thermal damage of the surrounding tissue and with the minimal mechanical injury, therefore Er:YAG laser could be considered as a good candidate for the TMLR.
Transmyocardial laser revascularization was found to be a new way how to convey oxygen-rich blood directly from the left ventricular cavity to the myocardium. In our study, a comparison has been made of the interaction of mid-IR solid state laser radiation with a myocardium tissue. For this purpose, the CTH:YAG, Tm:YAG and Er:YAG laser systems were designed, constructed and used for the interaction experiments. Besides those mid-IR lasers, the commercially produced CO<SUB>2</SUB> laser was used for the comparative study. The ablation coefficients were measured to be 0.029 mm/J for CTH:YAG laser radiation; 0.061 mm/J for Tm:YAG; 0.75 mm/J for CO<SUB>2</SUB>, and 10.5 mm/J for Er:YAG. From the histological examination follows that only the channels ablated by Er:YAG laser radiation are without any thermal damage of the surrounding tissue and with the minimal mechanical injury. As a conclusion - Er:YAG laser could be considered as a good candidate for the TMR besides CO<SUB>2</SUB> laser.
The capacity of erythrocytes to photohemolysis was researched in physiological solution with increasing percents of blood plasma by spectrophotometer Specord UV-VIS. The screening effect of plasma was founded during illumination of erythrocyte suspensions by completed light of the mercury lamp DRT-375. Much less effect was observed during the illumination of the light with (lambda) equals 365 nm. The screening effect of plasma was due to presence of a protein and aminoacid groups in plasma.