Pulse-dilation Framing Camera Research Articles

Influence of Magnetic Field on Space Charge Effect in Pulse-Dilation Framing Camera

Influence of Magnetic Field on Space Charge Effect in Pulse-Dilation Framing Camera

Analysis of Optimal Spatial Resolution Capability of Pulse-Dilation Framing Camera

Analysis of Optimal Spatial Resolution Capability of Pulse-Dilation Framing Camera

Improvement of Temporal Uniformity of Pulse-Dilation Framing Camera Using Pulse Superposition Technique

Improvement of Temporal Uniformity of Pulse-Dilation Framing Camera Using Pulse Superposition Technique

Imaging Performance of Double-Lens Pulse-Dilation Framing Camera

Imaging Performance of Double-Lens Pulse-Dilation Framing Camera

Rapid measurement of jitter time of MCP gating pulse in framing camera

A measurement system of exposure time is introduced. The jitter time MCP gating pulse is rapidly measured using an array of fiber bundle(AFB) and pulse-dilation framing camera. The research results show that the AFB is early or delay synchronized with MCP gating pulse by the pulse jitter result in the variation of position of maximum intensity of the dramatic imaging of the AFB. According to the variation of position, while the MCP gating pulse has a width of 200 ps and amplitude of −1.75 kV, the left and right jitter time of gating pulse are 61 ps and 73 ps, respectively. The measurement method provide a conveniently diagnosis to estimate jitter time of MCP gating pulse.

Influence of jitter time of dilating pulse on framing camera

The working principle of pulse-dilation framing camera is introduced and the influence of dilating pulse on the character of dilation is theoretically analyzed. The exposure time and dilation factor are measured using the an array of fiber bundle(AFB), the jitter time of dilating pulse is calculated by the relation between dilation factor and dilating pulse. The experimental results show that the dilation factor is instability by the jitter of dilating pulse and the jitter time of dilating pulse is calculated by variation of the dilation factor. When the photocathode is biased −3 kVdc, the maximum and minimum dilation factors are approximately 7.02× and 5.35×, where the AFB are respectively synchronized with the rising time on 290 ps and 174 ps in the dilating pulse. According to the deference of the two rising times, the jitter time of dilating pulse is 116 ps.

Measurement and analysis of temporal performance using different gradients of dilation pulse in the framing camera

A pulse-dilation framing camera is developed and the principle of pulse-dilation is introduced. The obtainment method of different gradient is discussed and implemented. The influence of gradients on temporal performance is theoretical and experimental studied. The research results show that the different gradients are achieved by altering resistance with between output port of the pulse generator and input port of the PC, the corresponding exposure time and dilation factor of measurement are agree well with the theoretical analysis. This research is verify and analyze the influence of gradient of dilation pulse on temporal performance of pulse-dilation framing camera.

Measurement of exposure time with less than 10-ps in the framing camera

A pulse-dilation framing camera and its working principle are introduced. The exposure time with less than 10-ps is measured by an array of fiber bundle. The research results show that the shortest exposure time and maximum dilation factor of camera are approximately 5 ps and 16.4×, respectively. The exposure time with less than 10-ps can be achieved when the drift potential is less than 5 kV and the gradient of dilation pulse is greater than 6 V/ps, those are provide feasibility for the framing camera with exposure time less than 10-ps.

Influence of gating pulse transmission on dilated property of pulse-dilation framing camera

The dilated property of pulse-dilation framing camera is achieved by exposure time, that is measured using fiber array. The influence of gating pulse on dilated property is analyzed. The results of research show that the dilated property had some errors of measurement and could be refined by the gating pulse transmission. When accelerating energy is 3 keV and the dilate gradient is 1.6 V/ps, the theoretical dilated property is 5.12 times, considering transmission direction of gating pulse before and after, the experimental dilated property is refined from 5.41 to 5.21 times and more closer to theoretical ones. The research is not only improve measuring accuracy of dilated property of pulse-dilation framing camera, but also proposed an optimization scheme for measuring exposure time by fiber array.

Measurement of dilation pulses using a pulse-dilation framing camera.

A pulse-dilation framing camera (PFC) and its working principle are introduced. The influence of the dilation pulse on the exposure time is discussed. The measurement of the dilation pulse using the PFC are theoretically analyzed and experimentally verified. The waveform and the entire time history of the potential of the dilation pulse are simulated by the known dilation factors of the PFC in theory, with the potential deviation at the end of the dilation time of pulse being approximately 3.2%. In the experiment, the exposure time and dilation factors of the PFC are measured by using an array of fiber bundles and in taking many measurements, the waveform and the entire time history of the potential of dilation pulse are achieved by the dilation factors, with the potential deviation at the end of the dilation time of pulse being approximately 6.3%. The research results show that the experimental measurement is consistent with theoretical analysis, although there are some deviations, and it is feasible to measure the waveform and the entire time history of the potential of dilation pulse using the PFC. Moreover, the research may provide an idea for new applications of the framing camera.

Research on imaging system and spatial performance of a pulse-dilation framing camera with larger drift area

An imaging system of pulse-dilation framing camera with a larger drift area is proposed, the magnetic field is calculated and the electronic trajectories is traced, the influence of larger drift area on spatial performance is analyzed, the lager detection area and high spatial resolution of framing camera with larger drift area is discussed. The research results show that the better spatial performance of framing camera with larger drift area is feasibility. When the accelerating energy is 2 keV, the sub-picoseconds pulse-dilation framing camera with Φ90 mm of detection area and 423 μm of spatial resolution is achieved, the femtoseconds ones with Φ40 mm of detection area and 448 μm of spatial resolution is obtained. This work provides a theoretical possibility for achieving higher spatial performance of sub-picoseconds/femtoseconds framing camera with larger drift area.

Investigating the temporal performance of a pulse-dilation framing camera with larger drift area

A pulse-dilation framing camera with a larger drift area is proposed, the influence of drift area on temporal performance of camera is analyzed, the femtosecond (fs) level of temporal resolution of camera is discussed. The research results show that the total temporal resolution of camera consisted of technical and physical temporal resolution, although the two types of temporal resolution exhibit an opposite tendency as the drift area is increased, the total temporal resolution can be achieved to femtosecond level by optimizing the accelerating potential and drift area. When the accelerating potential is set as −2 kV, the total temporal resolution is achieved to 939 fs using 1.0 m of drift area. This work provides theoretical basis for the feasibility of realizing a femtosecond framing camera.

The influence of leakage magnetic slit on imaging performance of framing camera

A pulse-dilation framing camera is designed using a combination of magnetic lenses. The axial magnetic field distribution, electronic trajectory and imaging distribution on the object plane are simulated, and the influence of leakage magnetic slit on imaging performance of camera is analyzed. Results show that increasing the leakage magnetic slit improves the imaging performance away from axial area. At an acceleration energy of 3keV, the width of magnetic slit increases from 10 to 70mm, the relative imaging dispersion degree between on-axis and off-axis decreases from 0.27 to 0.06, and the relative mean deflection angle decreases from 65.17° to 59.44°. These features contribute towards further optimization of structural parameters of the magnetic lens and provide design guidelines for achieving a pulse-dilation framing camera with better imaging performance.

Analysis of an extraordinary electron beam moiré phenomena in a pulse-dilation framing camera

An extraordinary electron beam moiré phenomena (EBMP) is generated with a pulse-dilation framing camera. The intrinsic relationship between the extraordinary EBMP and the imaging curved plane of camera is theoretically analyzed. The experimental results and analysis show that the extraordinary EBMP and mesh appear simultaneously, the extraordinary EBMP has two inclination angles and the maximum inclined angle of both is 106.78°. Moreover, the Gaussian imaging plane of the off-axis object point is theoretically simulated by examining photoelectron trajectories, where the inclined angle between the axis and 25 mm off-axis is approximately 112°. The theoretical results are very similar to experimental results, that is a significant phenomenon that may possibly expand the use of EBMP in pulse-dilation framing cameras to new applications.

Influence of lens aperture size on spatial performance of short magnetic focusing framing camera

In this work, a pulse-dilation framing camera with short magnetic focusing was studied. The magnetic field, electron trajectory and imaging distribution were simulated, the influence of magnetic lens aperture size on spatial performance was analyzed and improvements were discussed. The results show that the overall spatial performance was improved by enlarging the aperture and further improved by increasing the size of leakage magnetic slit, even if the spatial resolution of paraxial region became poorer. When the acceleration energy was 3 keV, leakage slit was 10 mm and aperture size was increased from 200 to 280 mm, the on-axis spatial resolution decreased from 92 to 130 μm, 45 mm off-axis spatial resolution improved from 618 and 456 μm and the coefficient of variable decreased from 0.59 to 0.40. Moreover, when the aperture was enlarged to 280 mm and leakage slit was increased to 40 mm, the on-axis spatial resolution, 45 mm off-axis spatial resolution, and coefficient of variable were 159 μm, 359 μm and 0.26, respectively. These results contribute towards further optimization of structural parameters of the short magnetic focusing system and provide design guidelines for achieving a pulse-dilation framing camera with detection area diameter of up to 90 mm(radius is 45 mm).

Analysis of spherical and comatic aberrations in a pulse-dilation framing camera

A pulse-dilation framing camera is a two-dimensional ultrafast diagnostic tool that is used to research spatiotemporal evolution of plasmas through pinhole array images in inertial confinement fusion experiments. This imaging technique uses a pulse dilated with magnetic focusing imaging. Aberrations exist in the images due to the influence of long drift area and magnetic focusing on photoelectron motion. These aberrations were simulated and measured in this study in order to further understand aberrations in a pulse-dilation framing camera. The results show that the spherical and comatic aberrations primarily affect the imaging quality during imaging of camera. The spherical aberration produces diffuse spots and reduces the spatial resolution for any point on the object (i.e., regardless of whether or not it lies on the optical axis). Meanwhile comatic aberration especially obvious occurs for off-axis points on the object. These results raise an important question regarding the development of larger object planes and multiple frames of cameras that remains to be resolved.

Measurement of electron beam moire fringes with pulsed-dilation framing camera using different lasers

The electron beam moire fringe (EBMF) is generated by using a pulse-dilation framing camera. Its characteristics are measured via a nanosecond- and a femtosecond-laser. The wavefront curvature radius of the two lasers is calculated based on the measurement of the EMBF rotation angle and this result is discussed in detail. The experiments show that the EBMF rotation angles measure 31.9° and 16.6°, while the wavefront curvature radii are 12.5 mm and 21.1 mm, when the ns-laser and the fs-laser are used, respectively. This study greatly contributes in the development of EBMF-based technologies and proposes novel application directions for the use of pulse-dilation framing cameras.

Analysis of the influence of the accelerating structure on the performance of pulse-dilation framing cameras

In this work a pulse-dilation framing camera was designed by employing a telescope imaging system. The accelerating electric field and the field emission current on the photocathode were simulated and the influence of the accelerating structure on the temporal and the spatial resolution performance of the camera were analyzed. The results reveal that the temporal and the spatial performance are drastically affected upon an increase in the accelerating distance from 1 mm to 5 mm. Moreover, the decrease of the electric field from 3 kV/mm to 0.6 kV/mm, which is caused by the increase of the temporal resolution of the camera from 3 ps to 4.5 ps are investigated. The decrease in the field emission current on the photocathode from 1.1 A/m2 to 0.21 A/m2 drastically affects the spatial resolution of the camera, which passes from 66.9 μm to 71.1 μm. This research provides a theoretical basis for the development of pulse-dilation framing cameras with higher temporal and spatial resolution.

Research on exposure-time uniformity of pulse-dilation framing camera

Framing cameras are important ultrafast diagnostic tools and used to study spatiotemporal evolution of plasmas through pinhole array images in inertial confinement fusion (ICF) experiments. The exposure-time (ET) and its uniformity are main factors for analyzing effect of plasma evolution. A 10-ps pulse-dilation framing camera typically has a non-uniform ET between array images, which limits its plasma diagnostic in ICF. Therefore, in order to obtain deeper insights into this drawback, ET uniformity of pulse-dilation framing camera is studied. The factors influencing ET uniformity are theoretically analyzed and camera system is built for experimental studies. Results show that the transmission of dilation pulse along the photocathode (PC) causes accelerating potential changes, in which result inconsistent ET at different positions of the PC. When gradient of dilation pulse is 2 V/ps, length of PC is 56 mm and acceleration energy is 3k eV, the ET is changed from 14.8ps(pulse dilation magnification is 6.22×) to 12.6ps(7.30×) in the process of transmission along the PC and the non-uniform rate is about 8%, that consistent with theoretical predictions. Furthermore, the research have important theoretical and practical significance for further understanding plasma evolution in ICF.

Performance evaluation of the imaging system of a pulse-dilation framing camera

The imaging system of pulse-dilation framing camera is designed using short magnetic focusing. The axially symmetric magnetic field distribution is simulated and the influence of imaging system on spatial resolution of camera is analyzed. Results show that the magnetic field of imaging system are Gaussian, humped and mountain shaped, when composed of one, two and three or more lenses, respectively. The diameter of detection area with better than 300-μm using three shaped of imaging system are Φ32-mm, Φ70-mm and Φ80-mm, which ratio to diameters of lens are 20%, 43.75% and 50%, respectively. The humped and mountain of imaging system are completely better than 30% ratio of dilation X-ray imager (DIXI) in particular. Studying the characteristics of magnetic field and imaging system shape provides important theoretical guidelines to further optimize and improve spatial resolution of pulse-dilation framing camera.