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.
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.
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.
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.
•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).
We present both an innovative theoretical model and an experimental validation of a molecular gas optically pumped far-infrared (OPFIR) laser at 0.25 THz that exhibits 10× greater efficiency (39% of ...the Manley–Rowe limit) and 1,000× smaller volume than comparable commercial lasers. Unlike previous OPFIR-laser models involving only a few energy levels that failed even qualitatively to match experiments at high pressures, our ab initio theory matches experiments quantitatively, within experimental uncertainties with no free parameters, by accurately capturing the interplay of millions of degrees of freedom in the laser. We show that previous OPFIR lasers were inefficient simply by being too large and that high powers favor high pressures and small cavities. We believe that these results will revive interest in OPFIR laser as a powerful and compact source of terahertz radiation.
The experimental results in studying lasing and pumping parameters of the CuBr laser with attypical excitation mode are presented in the paper. The excitation was provided by the single pulse mode ...with preliminary preparation of the active medium by pulse sequence (zug). The effect of the time delay between pulse sequence and single excitation pulse on the CuBr + Ne and CuBr + Ne + HBr media lasing was determined. It has been established that an increase in this time delay leads to an increase in the duration of the generation pulse. It was shown for the first time that lasing in a CuBr + Ne + HBr laser can be obtained with a relaxation time of the active medium up to 5 ms. The critical electron concentration which provides ability of generation for CuBr + Ne and CuBr + Ne + HBr media was experimentally shown.
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Gas laser cutting technology has several advantages over other methods of material separation. Reducing the roughness of the cut surface is practically an important task, since the roughness ...parameters have a significant effect on the operational properties of functional surfaces. The article presents the results of a comprehensive assessment of the microgeometry of the surface of a gas laser cut and studies of the microstructure of a two-layer steel material, high-speed steel grade Р9M4K8, deposited on 30KhGSA structural steel. The influence of the modes of gas laser cutting (cutting speed and laser radiation power) on the parameters of roughness, phase composition, and microhardness of the cut surface layers is investigated. It is shown that the roughness of the cut surface is comparable to the roughness of surfaces after machining and under certain conditions can be less than after mechanical or oxygen cutting. It is shown that the roughness parameters change depending on the distance to the upper edge of the cut. Correlation ratios of the main parameters of surface roughness after gas laser cutting have been determined and compared with similar ratios for surfaces after machining. It is also shown that the height parameters of roughness significantly depend on the cutting modes. No noticeable effect of the chemical composition of steels on the roughness of the cut surface was revealed. Analysis of the microstructure of the surface of steels after gas laser cutting showed that in the surface layer of the cut to a depth of more than 200 microns, the steels were re-hardened. In the hardening zone, the surface layer has an increased microhardness: for high-speed Р9M4K8 steel
HV
0.2
= 8760 ± 150 MPa, for 30KhGSA steel,
HV
0.2
= 6740 ± 90 MPa. The results make it possible to select the technological parameters of gas laser cutting that provide an optimal combination of microgeometry and mechanical properties of the cut surface, which makes it possible to reduce or eliminate subsequent processing.
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