V.V. Korobkin

Picosecond x-ray plasma radiation measurements

Abstract Direct picosecond measurements of X-ray laser plasma radiation were performed with a high-speed X-ray image-converter camera (ICC). This camera operates in the single-frame mode with an exposure time ranging from 5 ns to 0.5 μs and in the streak mode with 5 × 10 9 to 5 × 10 7 cm/s streak velocities. Its temporal resolution in the streak mode was calculated to be about 7 ps. A plasma was created by focussing 10 ps 1 to 2 joule laser pulses onto a titanium target placed in a vacuum chamber. The halfwidth of the recorded X-ray pulses varied from 30 to 60 ps.

High-speed image converter x-ray studies

Two X—ray high—speed image—converter cameras (ICC) have been developed. In the first one a soft X—ray radiation is converted into visible light with the aid of a 0.5ns response time, plastic scintillator. The second camera incorporates a photocathode which is sensitive to visible and X—ray radiation. Its calculated temporal resolution approaches 5—7 ps. Both developed cameras were employed for studies of X—ray radiation emitted by laser plasma. For the smooth nanosecond excited laser pulses, a noticeable amplitude modulation was recorded in all laser pulses reflected by plasma as well as in each third pulse of X—ray plasma radiation. It was also observed that the duration of X—ray plasma radiation is 20—40% shorter than that of the incident nanosecond laser pulses and this duration being 3–6 times longer than that of the picosecond irradiating pulses. The half—width of the recorded X—ray plasma pulses was 30—60 ps.

Finite-size image isochronism

Abstract Classical imaging tautochronism implies zero light transit-time variation over paths, connecting the point source with its image point. For a certain imaging class the variation is shown to be zero over two-dimensional objects and corresponding images. The area-isochronous imaging is surely important for pico and subpicosecond photography.

Spectral-temporal investigations of the backscattered radiation from laser plasma

Abstract Spectral and time-resolved investigations of the back-scattered light from aluminium laser-produced plasmas at frequencies ωL and 2ωL are performed. Good correlation between maxima of the scattered light at ωL and minima at 2ωL was discovered. This correlation has been predicted by the theory. These experiments show that the spectrum width and intensity of the second harmonic essentially depend on the velocity of the expanding plasma.

Studies of Different Recording Systems Associated with a Picosecond Streak Camera

A new commercial TSN 503–04 picosecond image—streak camera is investigated. This camera is developed for streak operation in 108 – 2.109 cm/s range with streak nonlinearities down to 10%. Four different recording possibilities for taking output screen picture are searched. Maximum temporal resolution obtained is better than 10–10s with RCA grid—shutter tube alone and it is around of 3 × 10–11s with external roicrochannel or roagneticcaly focused image—intensifiers. It is shown that TV—recording provides much more versitality for output image treatment.