Two-Stage Radio Frequency Power Generator-Amplifier Design for a TEM00 CO2 Slab Waveguide Laser
This letter presents the results of the research conducted on the design, construction and test of a two stage ra- dio frequency power generator-amplifier directed adapted to an in-house-built compact CO2 waveguide laser. The main characteristic of this power supply lies in the fact its design is based on MOSFET technology for both the oscillator and the amplifier stages. RF output power is centered at 81MHz frequency signal between 100W to 150W. The two-stage sys- tem device has a minimum electric conversion efficiency of 64%. Consequently, the laser head and RF excitation design must have an electrical termination of 50� impedance and the whole system may include a proper matching circuit. The overall test, for the entire system: RF excitation along with our CO2 laser head, is made with a typical gas mixture of CO2- N2-He with proportion of 1:1:3 correspondingly and at a final pressure of 40Torr. Under these specific conditions, a maximum optical output power of 10.7W was obtained for an input feed RF power of 147W. Regarding the optical qual- ity we measured the transverse mode of propagation TEM00 which indicate the entire system work very near the diffrac- tion limit specifications for similar laser systems.
RF generator for compact CO2 waveguide lasers
Abstract This letter reports the fabrication and testing of a compact Radio Frequency Generator (Oscillator-Amplifier) for its integration in a CO2 waveguide laser. The circuit uses a common source MOSFET transistor that has been modified for self-sustained oscillations impedance-matched to 50 Ω. RF power is supplied to the laser resonant cavity made of a ceramic–metal slab which is placed between a negative branch unstable optical resonator.
Imposing Transboundary Conservation
SUMMARY Attempts to impose regional conservation strategies from the top down without local participation are doomed to failure. Even so, this does not negate the critical importance of promoting international transboundary conservation. This paper draws on a research project which examined transboundary cooperation in the 136 complexes of protected areas that adjoin across international boundaries, examples of internationally divided ecosystems. The results of an international survey demonstrate that such transboundary cooperation is already occurring in 82% of the cases, although most of it is at relatively low levels. Analysis reveals that numerous different variables correlate with cooperation but, not surprisingly, the most important ones are distinctly human variables relating to human relationships. This strengthens the proposal that sustainability of conservation projects depends on inclusion of all stakeholders and development of a supportive constituency. While international organizations play crucial roles in educating, equipping, and facilitating transboundary conservation, they cannot impose it. International contributions are instrumental, but ultimate sustained success depends on the day-to-day involvement and efforts of those on the local level who must do the interacting.