M.G. Fedotov

Application of Synchrotron Radiation for Studying Detonation and Shock-Wave Processes

A new method of remote investigation of detonation and shock‐wave processes with the use of synchrotron radiation is proposed. The facility used for the first experiments with measurement of density and small‐angle x‐ray scattering in detonation of condensed explosives is described. The high time and spatial resolution of the techniques proposed allows one to determine the character and mechanism of destruction of the condensed phase and the growth dynamics of new structures, including crystalline ones, in detonation flows. The capabilities of the new technique are described.

Methods of research of the detonation and shock wave processes with the help of SR. Possibilities and prospects

Abstract The existing research methods are insufficient for investigation of the detonation physics because of very high pressure, rapidity and aggressiveness of explosion. Therefore, new methods allowing direct experimental investigation with the help of SR are of great interest. This paper suggests and describes realization of a new method for remote investigation of the detonation and shock wave processes with the help of SR. Presented below is a description of the experimental facility at which the first studies on the measurement of the passed radiation and small-angle X-ray scattering (SAXS) at detonation of condensed explosives were conducted.

“Moving source”: test realization at VEPP-3 of a diffraction experiment with nanosecond time resolution

Abstract The purpose of this work is a demonstration of the basic possibility of the practical realization of the “moving source” idea for X-ray diffraction with nanosecond time resolution. The idea of “moving source” was published earlier. The principle of this idea is: a quick change of electron trajectory by the kicker is responsible for a quick change of direction of synchrotron radiation (SR). In such a way a “moving source” can be created. Using the “moving source” it is possible to scan a sample with the SR beam. As a result, diffraction with nanoseconds time resolution can be achieved . The experiment at the VEPP-3 storage ring has confirmed such a possibility. The following answers to the main questions were received: (1) SR intensities are enough for obtaining satisfactory statistics from one bunch (2) it is possible to realize synchronization of an impact with the motion of electrons in the storage ring and with the systems of image registration ; (3) it is possible to compensate the betatron oscillation which has arisen after the impact; (4) the background conditions are not so bad and do not hinder the registration of the diffracted radiation.

First UV/visible lasing with the OK-4/Duke storage-ring FEL: design and initial performance

The OK-4/Duke storage ring FEL was commissioned in November 1996 and demonstrated lasing in the near UV and visible ranges (345 - 413 nm). The OK-4 is the first storage ring FEL with the shortest wavelength and highest power for UV FELs operating in the United States. During one month of operation we have performed preliminary measurements of the main parameters of the OK-4 FEL: its gain, lasing power and temporal structure. In addition to lasing, the OK-4/Duke FEL generated a nearly monochromatic (1% FWHM) 12.2 MeV gamma-ray beam. In this paper we describe the design and initial performance of the OK-4/Duke storage ring FEL. We compare our predictions with lasing results. Our attempt to lase in the deep UV range (around 193 nm) is discussed. The OK-4 diagnostic systems and performance of its optical cavity are briefly described.

Stabilization system of synchrotron radiation beams at the VEPP-3 storage ring

Abstract The system for position stabilization of synchrotron radiation (SR) beams at the VEPP-3 storage ring (Novosibirsk, Russia) is described. The system is based on measuring, at the same place, the positions of two SR beams emitted from different points of electron orbit in the storage ring. The results of the system testing and estimations of residual orbit instability under the system control are presented, as well.

Synchrotron radiation instrumentation for “in situ” investigation of explosion with nanosecond time resolution

Abstract A special instrumentation was developed for the investigation of explosions by synchrotron radiation with 250ns time resolution. It consists of an explosion chamber, detonation front sensors (wire detectors) and X-ray detectors. The time dependence of the absorption coefficient of the explosive material was measured during the explosion. In the same experiments, the SAXS and the diffraction signal were observed. In the first experiments, hexogen-TNT alloy was used to obtain diamond powder as explosion product. In this experiment the SAXS intensity increased sharply for 1500ns. This is an unusual result, because according to theory, most chemical transformations finish in about 200ns. The test experiment has shown that it is possible to receive a time resolution of 20ns.

CCD detectors for X-ray synchrotron radiation application

Abstract In this paper the possibility of the application of some types of CCDs for the study of fast processes (by recording an image formed by a short flash of synchrotron radiation) is considered. The first results of model experiments are also described.

Observation of Compression and Failure Waves in PMMA by Means of Synchrotron Radiation

The possibility of using synchrotron radiation for density measurements in shock‐compressed polymethylmethacrylate destroyed in a failure wave is demonstrated for the first time. Parameters of the compression and failure processes are presented.

Multi-spectrozonal detectors for temporal-resolved SR experiments

Abstract This paper considers the structure of the special integrating-mode X-ray detectors allowing the division of the range of their working energies into a few relatively independent sub-ranges. The recording of signals for all sub-ranges is carried out simultaneously (during one bunch passing in the SR source) and from the same area of the detector. It is expected that the application of such detectors for the studies of short-time processes will permit estimation of the variation of the spectrum of the recorded radiation, which violently simplifies the interpretation of the results.

Peculiarities of CCD and photodiode arrays application to X-ray image detection

Abstract Some properties such as diffusion noise, time and spatial distortions, etc., of solid-state semiconductor imagers in the X-ray region are described. The influence of these properties on the performance of one- and two-dimensional rapid image detection systems based on matrix CCDs is discussed.