Measurement of back-bombardment temperature rise in microwave thermionic electron guns.

We describe a simple method to measure the back-bombardment heating temperature rise as a function of time in pulsed microwave thermionic guns using a fast rise-time InGaAs detector and optical pyrometer. Gaining knowledge of the nature of that temperature rise and the corresponding current out of the gun are the first steps in devising a scheme to counteract the back-bombardment heating which lengthens the micropulses, limits the macropulse length, and increases the energy spread of the emitted electron beam. We measured a temperature rise of 59 K in our LaB6 cathode which delivered a peak of 600 mA over a 5 μs RF pulse in our 0.

Remote Raman spectra of benzene obtained from 217 meters using a single 532 nm laser pulse.

This report describes a mobile Raman lidar system that has been developed for spectral measurements of samples located remotely at ranges of hundreds of meters. The performance of this system has been quantitatively verified in a lidar calibration experiment using a hard target of standardized reflectance. A new record in detection range was achieved for remote Raman systems using 532 nm laser excitation.

Brain ablation in the rat cerebral cortex using a tunable-free electron laser.

Background And Objectives: We used the MARK III free electron laser (FEL) tuned to molecular vibrational absorbance maxima in the infrared (IR) wavelength range of 3.0-6.45 microm to study the effect of these various wavelengths and a power level of 5 mJ/2 microseconds macropulse on photoablation of CNS tissue.