摘要
X射线皮秒变象管扫描相机是一种应用变象管技术测量X射线波段脉冲辐射而能达到皮秒级时间分辨率和微米级空间分辨率的时空测试系统,是高功率激光打靶产生等离子体诊断的有力工具。时间分辨率和空间分辨率是X射线皮秒变象管扫描相机最基本的性能参数。这些参数的测量有其不同于可见光扫描相机的特殊性。
The methods and the results of the measurements of the temporal and spatial resolution of our x-ray streak camera are described.The temporal resolution measurement is performed by the delta response method. A train of powerful shorr iaser pulses with known separation formed by F-P etalon shot onto a plane Au target generating short x-ray pulse which can be seen as a delta light source- When the x-ray pulse is measured by our streak camera the half width of the streak image obtained by the camera is considered to be the temporal resolution of the camera.The laser oscillator was a passively mode-locked Nd:YAG system producing pulses of -60ps duration. The duration of the generated x-ray pulses is much longer than the laser pulse. A multilayer filter made by polypropylene coated with Al and Formvar coated with Ti was used to remove the softer and longer x-ray component. With this filter we have obtained the temporal resolution of 33 ps of the camera. Later, an antiresonant ring cavity Nd:YAG osillator was used to get even short 1.06μm pulse that is about 8ps. When this system was used temporal resolution of 55 ps was obtained only with the filter of polypropylene coated with Al.When the static spatial resolution of our x-ray streak camera with demountable pho-tocathode was measured, the x-ray image converter tube was put in a vacuum chamber with a static x-ray source. Conventionally, a grid shield is put at the front of photoca-thode to form a x-ray shadow image of the grid. But when the x-ray source is riot a point or collimated one the shadow image can become confusion. In odcr to overcome the defect we used a grid form photocathode to replace the grid shield. This photocathode was formed with a grid mask in the vacuum diposition of the cathode. This kind of photocathode play the roles of both grid shield and photocathode. Using this grid form photocathode that makes the image clear the static spatial resolution of our camera up to 20lp/mm and the dynamic spatial resolution of 5 Ip/mm have been obtained.
关键词
扫描
相机
X线
时空分辨率
变象管
x-ray screak cameras, time resolution, spatial resolution
