One of the key challenges in the design of gas lasers powered by pulsed power circuits pertains to reducing the flow of current through the electrodes during the filamentary discharge phase. This ...phase occurs after the lasing period ("volume glow") is terminated due to discharge instabilities and the current flow during this period is referred to as late currents. Late currents contribute to electrode erosion. The ejected electrode material contaminates the gas, and lowering the service life of the laser. Snubber circuits are an economic solution to reducing late currents in pulsed power circuits that do not employ a magnetic switch. In a simple snubber, which is connected directly across the main storage/drive capacitor <inline-formula> <tex-math notation="LaTeX">C_{0} </tex-math></inline-formula>, it was found that the stray series inductances of both <inline-formula> <tex-math notation="LaTeX">C_{0} </tex-math></inline-formula> and the high voltage snubber diodes significantly reduced the magnitude of current flowing through the snubber. A new coaxial capacitor and snubber assembly was proposed to improve the effectiveness of the snubber in reducing the late currents. The design exploited the high degree of mutual coupling between the concentric coaxial cylinders to reduce the total inductance in the snubber loop. Experimental results showed an almost 40% reduction in the total charge that flows through the discharge in the late currents stage. Although the improvement was significant, it is expected that improvements to the construction quality of the prototype could potentially lower the late currents even further.
Results of offline commissioning tests for a new dedicated gas cell for the Mass Analysing Recoil Apparatus (MARA) Low-Energy Branch are reported. Evacuation time, ion survival and transport ...efficiency in helium buffer gas were characterized with a radioactive 223Raα-recoil source. Suppression of the ion signal, originating from non-neutralized species in the gas cell, was explored with 219Rn ions, the daughter recoil of 223Ra, as a function of voltage applied to one of the ion-collector electrodes. Two-step laser resonance ionization of stable tin isotopes produced inside the gas cell from a heated bronze filament was demonstrated, and broadening of the atomic resonances in argon buffer gas was studied. These tests indicate the suitability of the new gas cell for future in-gas laser spectroscopy studies of exotic nuclei at the Accelerator Laboratory of the University of Jyväskylä.
In this paper, the tendency is towards looking for a correction factor in the diffraction loss from (TEM01) in order to search for the same parameters, diffraction loss in a cavity has standing ...(TEM01) modes. This will be through a lengthy analysis in the far-field intensities the waves via – Gaussian beam shaped wave patterns. The analysis is in the same criteria as that of (TEM00) modes, except for a little complicating factor in the round-trip by pass on the surface of the aperture mirror. The results showed that the diffraction loss procedure is just the continuate for the earlier work, except that the field intensities change for TEM01, as that of TEM00, as such, it has a direct effect on the equation fitting it. The Combination of experimental and Theoretical results in this study are in excellent agreement as in g = 0.80 and they were both functions of the physical parameters of the active medium and the laser resonator.
Long pulse gas lasers utilizing double-discharge circuits are different from the single-short pulse gas lasers in that they do not require all of the desired energy to be deposited into the peaking ...capacitors prior to ignition of the main gap. Instead, the majority of the energy is held in another capacitor that is then discharged in the form of a longer duration discharge pulse output compared with that of single-short pulse lasers. Extended stability of the discharge is typically achieved by igniting the main gap discharge at higher ignition voltages. Several double-discharge circuit topologies exist in the literature. However, each topology has its own disadvantages primarily centered around the components needed and the resulting complexity. In this article we introduce the application of the new hybrid circuit pulsed power topology as a double-discharge circuit with high ignition voltages. The hybrid circuit pulsed power topology was originally published by the authors of this article in their previous publication titled "A New Hybrid Pulsed Power Circuit Topology for Gas Laser Applications." The advantage of the hybrid circuit as a double-discharge circuit is that it does not require any special device e.g., semiconductor opening switch (SOS) diode and can use commonly available components.
We reported here a high-efficiency, high peak-power, narrow linewidth 1.9 μm fiber gas Raman amplifier based on stimulated Raman scattering (SRS) in an H 2 -filled antiresonance hollow-core fiber. A ...CW seed fiber laser near 1908 nm is amplified by the first vibrational Stokes wave of hydrogen molecules while pumping with a pulsed 1064 nm microchip laser. The seed laser significantly enhances the vibrational SRS and suppresses the rotational SRS, resulting in a record optical-to-optical conversion efficiency of ~41% (quantum efficiency ~73.5%) for such H 2 vibrational Raman experiments in hollow-core fibers, with 1.4 m fiber and only 3 bar H 2 , which is more preferable in applications. The maximum average Stokes power of 74.2 mW and the peak power of ~150 kW with the linewidth about 1 GHz (~12 pm) are obtained. The linewidth characteristics of such fiber gas Raman laser sources are systematically studied for the first time by experimental methods. This paper provides an effective method to obtain efficient 1.9 μm fiber sources of both high peak power and narrow linewidth.
The paper presents the results of the research and development the brightness amplifier excited by longitudinal capacitive discharge with a pulse repetition frequency (PRF) up to 24 kHz for using in ...systems with optical signal amplification. The amplification features of the active element were experimentally studied. The results of the use the designed brightness amplifier in the MOPA system and in the laser monitors (bistatic and monostatic) demonstrate the efficiency of the designed active element for an optical signal amplification. The effect of the vapor concentration in the medium on image brightness amplification characteristics was experimentally estimated. The concentration of the CuBr vapors should be lower to provide the optimal features of laser monitors. The difference between concentration provided maximum output power and optimal active optical system parameters reaches 25%–30%. The contrast of the images in the monostatic and bistatic laser monitors higher 90%.
•CuBr brightness amplifier excited by longitudinal capacitive discharge was developed.•The effect of the vapor concentration in the medium on image brightness amplification characteristics was experimentally estimated.•The results of the use the designed brightness amplifier in the MOPA system and in the laser monitors (bistatic and monostatic) are presented.
The novel and sensitive In-Gas Laser Ionization Spectroscopy (IGLIS) technique enables high-precision laser spectroscopy of the heaviest elements and isotopes very far from stability that are ...produced in fusion-evaporation reactions at in-flight separators. Powerful and dedicated laser systems are required in these facilities to realize in-gas jet laser spectroscopy with optimal spectral resolution and efficiency. The performance with respect to the requirements for IGLIS studies at the low energy front-end of the Super Separator Spectrometer (S3) at GANIL, France, of Dye and Ti:sapphire laser systems is investigated. In addition, a number of specific experimental cases on key isotopes of the elements Ag, Sn, Ac, and No are discussed in detail.
Magnetic pulse compression (MPC) circuits are commonly used in pulsed power circuits for powering gas lasers to shorten the duration of the pulse. If the core of every magnetic switch in the MPC is ...biased to <inline-formula> <tex-math notation="LaTeX">-\Delta B_{r}</tex-math> </inline-formula> by a reset circuit, then the voltage hold-off time is doubled, and the cross-sectional area required is halved. Reset circuits must be isolated from the high-voltage pulses appearing in the pulsed power circuit using filters. The required filter (inductor) size becomes too large if the reset circuit is connected directly in parallel to the magnetic switches, especially if the volt-sec product across the filter inductor is large. The most common, existing reset circuits available in the literature directly connect in parallel to the magnetic switch (<inline-formula> <tex-math notation="LaTeX">s</tex-math> </inline-formula>) and, therefore, require larger filter sizes to protect the reset circuitry. In addition, reset circuits cannot always be wound on the magnetic core to create a step-down transformation of the pulsed power voltages (lack of physical space or the use of a single primary winding). This article proposes a new reset circuit topology which resolves these problems by enabling the use of the smallest possible filter size (inductance value). In addition, only a single reset circuit is needed to reset multiple magnetic switches in the MPC network. An active reset circuit is also proposed which is more suitable for resetting magnetic cores that are relatively harder, i.e., requiring higher H values to saturate (equivalent currents greater than a few amperes). The reset circuits discussed in this article can in general be applied to many pulsed power applications employing MPC networks.
•Pressure shift and broadening rates of 640.2 nm neon line were measured.•Natural neon isotope mix requires specially designed spectral line profile.•Cheap multi-mode diode lasers can be tailored for ...spectroscopy needs.•Starters for fluorescent lamps can produce reference optical frequency.
Measurements of pressure broadening and shift coefficients for 640.2 nm Ne line were performed in an RF discharge without stabilization of neutral gas temperature. A diode laser with a short external cavity was used for metastable neon absorption spectroscopy in a natural mixture of neon isotopes. An appropriate fit function was constructed permitting deduction of Doppler and Lorentz components for the Voigt profile of the spectral line. To determine pressure broadening ξ and shift β coefficients for pure Ne and Ne:He mixture we used the information about Lorentz linewidth, position of the line center and gas temperature derived from spectral line shape fitted to a model line profile. The values of the collisional coefficients reduced to 300 K in units of 10-10 s-1 cm3, are ξNe-Ne = (1.9±0.2), ξNe-He = (3.4±0.2); βNe-Ne = -(0.7±0.1), βNe-He = (0.13±0.04).
A major decision surrounding the design of pulsed power circuits for gas lasers is the choice between a thyratron and solid-state switches. The thyratron is a mature device technology whose cost is ...increasing. The ratings of solid-state switches still do not match those of a thyratron. Pulse transformer and pulse compression circuits must be added to overcome the lower ratings of solid-state switches leading to a higher parts count and cost. This article proposes a new solid-state pulse power topology called the hybrid circuit topology to address the parts count and cost issue. The hybrid circuit makes use of a combination of capacitive and inductive energy storage to reduce the time required to transfer the energy from the transformer primary to the secondary side. This ultimately reduces the quantity of magnetic material used in the pulse compression circuit.
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