Carbon-fiber Discharge Plasmas as a Soft X-ray Source for Calibration

我们提出用碳纤维放电等离子体作为软X射线源，用于探测器和光谱仪器的校准。提出了两种将直径为7微米的脆性碳纤维安装在放电电极之间的方法。(1)在充满水的放电室中，使用一对微型镊子从纤维夹持器中拾取纤维。(2)一种加载系统，其具有包含光纤的盒和能够将光纤安装在真空室中的真空密封加载器。将1 mm厚的盘状塑料闪烁体与光纤相结合，设计了一种结构紧凑、响应快的X射线传感器。在三种环境条件下考察了碳纤维的放电特性。(1)在大气层压力下，冲击波从纤维表面产生，并在周围空气中传播。放电电流流经两个区域，即空气的纤维和冲击加热的等离子体。(2)在水中，电流只在碳等离子体中流动。通过考虑退化态的理论方程，得到了掌骨的电导率。(3)在真空中，纤维的一部分蒸发并进入等离子体状态。提出了一种用石墨插层材料对碳纤维放电的可调谐X射线光源。为了验证这一想法，我们测量了镀铜碳纤维放电中的X射线发射。

We proposed carbon-fiber discharge plasmas as a soft X-ray source for calibration of detectors and spectroscopic instruments. Two methods have been developed for installing brittle carbon-fiber of 7 <micro> m in diameter between discharge electrodes. (1) A pair of microtweezers is used to pick up the fiber from a fiber holder in a water-filled discharge chamber. (2) A loading system with a cartridge containing the fiber and a vacuum sealed loader enabled to install the fiber in a vacuum chamber. A compact and fast response X-ray sensor is devised by combining a 1 mm thick disc-shaped plastic scintillator and a optical fiber. Carbon-fiber discharge characteristics have been examined in three environmental conditions. (1) In atomospheric pressure, a shock wave originates at the surface of the fiber and propagates in the surrounding air. The discharge current flows through two regions, namely, the fiber and the shock heated plasma of the air. (2) In water, the current flows in the carbon plasma only. The electrical conductivity of the palsma is obtained by the theoretical equation considering degerated states. (3) In vacuum, a part of the fiber evaporates and comes to a plasma state. A tunable X-ray source is proposed by discharging the carbon-fiber with graphite intercalated materials. To examine this idea, X-ray emission is measured in a copper coated carbon-fiber discharge.