Search

—A method is described for recording X-rays with a spectral resolution of λ/Δλ ≈ 20 in five spectral channels in the 0.15–1.0 keV energy range and a time resolution of ∼30 ps based on multilayer X-ray mirrors and an X-ray electron-optical streak camera. The technique is used to register the dynamics of the formation of the X-ray radiation field in the converter cavity.

In this article, radio frequency (RF) phase modulation (PM) technology is introduced to effectively improve the beam lifetime and study the longitudinal beam dynamics at Hefei Light Source-II (HLS-II) storage ring. In the experiment, an optical streak camera is employed for real-time observation of the longitudinal distribution and the bunch lengthening under the single-bunch operation mode. Simultaneously, the mechanism of island formation and annihilation caused by PM is deeply investigated based on theoretical analysis and preliminary online experimental measurements. The measured results are in good agreement with the theoretical simulation results. The applicable bunch lengthening factor and the optimal beam lifetime improvement factor are obtained as 2.01 and 1.87, respectively, over the range 20.2–20.7 kHz, which is in the vicinity of the synchrotron frequency. In addition, we further analyze and discuss the corresponding relationship between the modulation frequency and other characteristic parameters of HLS-II, such as the beam size, emittance, and energy spread, under PM.

The evolution of a microsecond pulsed barrier discharge initiated in atmospheric pressure air in the point–plane electrode geometry has been investigated using streak camera photorecording and shadow photography with micrometer resolution and nanosecond exposure. It has been shown that the discharge develops in series and its structure evolves both within a series and from series to series. It has been found that, irrespective of the polarity of a feed voltage pulse, the discharge develops from the point electrode, having the form of a set of many micrometer-diameter channels. At the late stage, the discharge consists of a number of glowing microstructured channels, which occupy the space between the point and barrier and deviate from the point axis, and many faint channels radially propagating over the surface of the barrier. Numerical parameters of the structured have been obtained.

We report thermometry and new Raman linewidth data using a novel method for time-domain rotational coherent anti-Stokes Raman spectroscopy (RCARS) on single-shot basis. The coherences are generated by two fs pulses and probed by a ns pulse. The resulting signal is detected using a combined spectrograph/streak camera setup with high spectral and temporal resolution. Rotational CARS spectrograms of nitrogen (N2), ethylene (C2H4), ethane (C2H6), and argon (Ar) are demonstrated at ambient condition. Self-broadened N2–N2 S-branch Raman linewidths were measured on single-shot basis and show excellent agreement with literature values. Furthermore, Raman linewidths of N2 S-branch perturbed by C2H4 and C2H6 were measured for the first time. The time-resolved approach was also utilized to separate complex spectra from a mixture of species through their difference in coherence lifetimes. Since the Raman coherences decay much faster for both ethane and ethylene than for nitrogen, pure nitrogen spectra could be obtained by analyzing only the temporal tail of the signal. Moreover, a model for time-resolved RCARS of N2 was developed, which employs the single-shot measured Raman linewidths to calculate the corresponding spectro-temporally resolved spectrograms at different temperatures. The model was used to evaluate the temperature from single-shot data of an N2/C2H6 mixture, showing very high accuracy. The demonstrated method constitutes an essential improvement for single-shot thermometry as it does not require pre-knowledge about collider species concentrations and their impact on linewidths.

A method for measuring the response time (dead time) of a streak camera (SC) for several sweep durations is presented. As a rule, the response time of an SC is measured only for the shortest sweep, which makes it difficult to synchronize the trigger pulse of an SC with a studied process when working on other sweeps. The use of a laser diode with a front of at most 1 ns as a light-pulse marker significantly reduced the uncertainty of the moment when the pulse appears on the camera. In addition, the proposed method allows one to take all possible response delays into account, thus increasing the accuracy of the measurements, as well as to measure the duration of SC sweeps.

Attosecond pulses have potential applications in the fields of physics, chemistry, biology, and medicine owing to the extremely high time resolution brought by their extremely short pulse widths. The generation and measurement technology of attosecond pulses provides a powerful means for the study of electron dynamical process in atoms. Since the date of its birth, the time width of an attosecond pulse has become shorter and shorter, making its measurement a challenging task. Although attosecond pulses are more and more widely used in the study of ultrafast dynamics and more interest is attracted into the field of attosecond science, it is undeniable that there are still difficulties and challenges for the measurement of attosecond pulses. This review is divided into two parts. The first part presents the development of technics for characterizing attosecond pulses, and briefly describes several experimental principles, setups and results for acquiring time-domain information of attosecond pulses, including RABITT (reconstruction of attosecond beating by interference of two-photon transitions) and laser-assisted lateral X-ray photoionization for measuring attosecond pulse train, attosecond streak camera for measuring single attosecond pulses, TIPTOE (tunneling ionization with a perturbation for the time-domain observation of an electric field) for measuring time-domain information of periodic pulses, as well as theoretical proposals such as attosecond cross correlation, asymmetric photoionization method, and SPIDER (attosecond spectral phase interferometry for direct electric-field reconstruction). The second part introduces the principle and structure of inversion algorithms for extracting time-domain information of attosecond pulses from spectrograms obtained with an attosecond streak camera, including FROG-CRAB (frequency resolved optical gating for complete reconstruction of attosecond bursts), PROOF (phase retrieval by omega oscillation filtering), VTGPA (Volkov transform generalized projections algorithm), PROBP-AC (phase retrieval of broadband pulses with autocorrelation) and CVGN (conditional variational generative network). We also evaluate the calculation time and accuracy of the algorithms. Finally, we summarize the experimental and theoretical challenges of the characterization of attosecond pulses, and look forward to the future development of attosecond pulse measurement.

In this article, a new data treatment based on time-resolved photoluminescence is presented. It works as a streak camera for infrared. A time-resolved photoluminescence spectrum for the HgCd0.33Te0.67 sample at 120 K was performed and analyzed. Typical time-resolved photoluminescence measurements, to compare our results with literature, were conducted. An interpretation of the behavior for three different time constants found in the signal is proposed.

The in-depth understanding of beam collective effects in the damping ring (DR) of the VEPP-5 injection complex at BINP is essential for optimizing its operation. Towards this, beam longitudinal profiles at the stage of injection into the DR and for a high-current stored beam have been measured using a streak camera and a dissector. The process of linac-beam capture into the DR has been simulated, and characteristic parameters of the DR impedance have been obtained. The results of these studies are reported in this paper.