A Ho:YLF laser pumped HBr molecular laser was developed that produced up to 2.5 mJ of energy in the 4 micron wavelength region. The Ho:YLF laser was fiber pumped using a commercial Tm:fibre laser. The Ho:YLF laser was operated in a single longitudinal mode via injection seeding with a narrow band diode laser which in turn was locked to one of the HBr transitions. The behavior of the HBr laser was described using a rate equation mathematical model and this was solved numerically. Good agreement both qualitatively and quantitatively between the model and experimental results was obtained.

An inexpensive, compact, three-electrode ͑trigatron͒ switch utilizing transverse gas flow was developed for burst-mode applications. The switch is cooled by adiabatic expansion from three built-in miniature nozzles and the interacting flow streams serve to sweep hot discharge gases from the electrode region. Tests demonstrated control of an average power of 100 kW for 10 s bursts at repetition rates up to 100 pulses per second ͑pps͒ while maintaining a hold-off voltage up to 50 kV. Under these conditions, the switch commuted currents up to 6 kA with a pulsewidth of 10 s. The cost of operation is reduced by using oil-free and dry air at a supply pressure of 500-1000 kPa and a mass flow rate of 0.5-8 g/s. Minimum switch jitter is obtained using a rounded-tip trigger pin flush with the adjacent electrode and an optimum trigger voltage that causes breakdown first between the trigger pin and opposite electrode.

Heparinized porcine blood and plasma, at constant hydrostatic pressure, was allowed to flow through a 5-mm incision in a small piece of porcine skin. Changes in the exuded blood volume were measured, and the incision site was examined microscopically. When normal blood flowed through either normal or von Willebrand skin, the exuded blood volume decreased gradually and eventually stopped. Microscopic examination revealed a platelet plug in the incision site. This plug was positive for Willebrand factor when examined by immunofluorescence. In contrast, the blood from von Willebrand pigs continued to flow constantly, and a platelet plug was not seen. The delayed in vitro hemostasis in von Willebrand blood was corrected to the normal range by the addition of either normal plasma or partially purified Willebrand factor. Normal blood, in which the Willebrand factor was immunologically inhibited, showed delayed hemostasis. For this in vitro system, it appeared that plasmatic Willebrand factor played an essential role in hemostasis.

A numerical model of a three-mirror resonator for a TE CO(2) laser was developed. This model was used to determine if a three-mirror resonator with an etalon could be used to ensure tunable single-mode action on the lower gain lines of CO(2). Single-mode pulse energies were also predicted and good agreement was found with experimentally measured values. An analysis of the thermal frequency drift of the resonator is also presented.

Laser-wakefield accelerators (LWFAs) driven by widely available 100s TW-class near-infrared laser systems have been shown to produce GeV-level electron beams with 10s–100s pC charge in centimetre-scale plasma. As the strength of the ponderomotive force is proportional to the square of the laser wavelength, more efficient LWFAs could be realised using longer wavelength lasers. Here we present a numerical study showing that $$10.6\,\upmu \hbox {m}$$ 10.6 μ m , sub-picosecond CO2 lasers with peak powers of 100–800 TW can produce high-charge electron beams, exceeding that possible from LWFAs driven by femtosecond near-infrared lasers by up to three orders of magnitude. Depending on the laser and plasma parameters, electron beams with 10s MeV to GeV energy and 1–100 nC charge can be generated in 10–200 mm long plasma or gas media without requiring external guiding. The laser-to-electron energy conversion efficiency can be up to 70% and currents of 100s kA are achievable. A CO2 laser driven LWFA could be useful for applications requiring compact and industrially robust accelerators and radiations sources.