Observation of the nonlinear effect in relativistic Thomson scattering of electron and laser beams

Thomson scattering of high-power laser and electron beams is a good test of electrodynamics in the high-field region. We demonstrated production of high-intensity X-rays in the head-on collision of a CO₂ laser and 60-MeV electron beams at Brookhaven National Laboratory, Accelerator Test Facility. The energy of an X-ray photon was limited at 6.5 keV in the linear (lowest order) Thomson scattering, but the nonlinear (higher order) process produces higher energy X-rays. We measured the angular distribution of the high-energy X-rays and confirmed that it agrees with theoretical predictions.     

Synthesis, Crystalline Structure, and Spectra of 3,3-Dimethyl-1-(3-methyl-1-phenylpyrazol-5-onylidene-4)-1,2,3,4-tetrahydroisoquinoline

3,3-Dimethyl-1-(3-methyl-1-phenylpyrazol-5-onylidene-4)-1,2,3,4-tetrahydroisoquinoline has been synthesized and its crystalline and molecular structures determined. It was found by IR and electronic absorption spectroscopic methods that the structure of this compound is not changed in solutions.     

Electromagnetic wave scattering in a semi-bounded plasma-molecular medium

The phenomenon of noncoherent wave reflection associated with scattering by electromagnetic fluctuations in a semibounded plasma-molecular medium is studied. The differential reflection coefficients are computed for scattering by collective bulk and surface fluctuations.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 79–82, May, 1987.     

Modal control of multi-input systems of neutral type with retarded argument

We suggest a special choice of a basis in the linear span of columns of the “controllability matrix” for multi-input systems of neutral type with retarded argument, which permits one to obtain an effective sufficient solvability condition for the modal control problem for such systems. The proof of this condition provides a constructive way for designing the desired regulator by the feedback principle on the basis of the solution of linear algebraic systems over the ring of bivariate polynomials.     

Laser-induced cavities and solitons in overcritical hydrogen plasma

A picosecond CO₂ laser was used successfully in a number of experiments exploring advanced methods of particle acceleration [1]. Proton acceleration from gas-jet plasma exemplifies another advantage of employing the increase in laser wavelength from the optical to the mid-IR region. Recent theoretical- and experimental-studies of ion acceleration from laser-generated plasma point to better ways to control the ion beam’s energy when plasma approaches the critical density. Studying this regime with solid-state lasers is problematic due to the dearth of plasma sources at the critical electron density ∼10²¹ cm⁻³, corresponding to laser wavelength λ = 1 μm. CO₂ laser offers a solution. The CO₂ laser’s 10 μm wavelength shifts the critical plasma density to 10¹⁹ cm⁻³, a value attainable with gas jets. Capitalizing on this approach, we focused a circular polarized 1-TW CO₂ laser beam onto a hydrogen gas jet and observed a monoenergetic proton beam in the 1–2 MeV range. Simultaneously, we optically probed the laser/plasma interaction region with visible light, revealing holes bored by radiation pressure, as well as quasi-stationary soliton-like plasma formations. Our findings from 2D PIC simulations agree with experimental results and aid in their interpretation.     

Possibilities of a refined method of calculating plane vibrations of lamellar bodies

Institute of Mechanics, Academy of sciences of the Ukrainian SSR, Kiev. Translated from Prikladnaya Mekhanika, Vol. 27, No. 11, pp. 69–77, November, 1991.