# Characterization of an X-ray Source Generated by a Portable Low-Current X-Pinch
## 1 Introduction  
Pulsed-power plasma devices loaded as Z-pinch, X-pinch, wire arrays, or liners have the ability to reproduce a vast variety of plasmas, such as dense plasmas for fusion studies, laboratory astrophysics plasmas, dense and hot point-source plasmas for hard X-ray generation, and lower density hot plasmas. Since the first realization by [PERSON] et al. [1], X-pinch plasmas driven by pulsed-power machines have been efficiently used as bright-point sources for X-ray radiation in applications such as point-projection radiography of plasmas [2, 3], X-ray microscopy for biological samples [4, 5, 3], and inertial confinement fusion capsules [6]. The small size of these devices and the predictable location of the radiation source [7] also make them favorable for applications such as X-ray backlighting [8] and microlithography [9]. This variety of applications requires an energy range of radiation from 1 to 12 keV [4, 10].  
In the X-pinch wire configuration, plasmas are typically produced by two wires touching at the cross-point, forming an \"X\". At that point, a hot, dense plasma is produced (the pinching effect), and energetic X-rays (\(\sim\)1-8 keV) are emitted for a short ns or sub-ns time duration [11]. Moreover, the X-ray burst can be related to the hot-spot (size \(\sim\)1 \(\upmu\)m; electron temperature \(\sim\)1 keV) formation [11]. Progressively, and immediately after thegeneration of the thermal X-ray burst, a very low plasma density gap of several mm, which is accompanied by the generation of an electron beam, is formed. This process leads to non-thermal X-ray radiation, which is associated with bremsstrahlung photons--in the \(\sim\)8-100 keV energy range--produced by electrons accelerating across that gap [12,13].  
The aim of this study is to characterize the X-pinch scheme as an efficient source of soft X-rays. A tabletop pulsed-power plasma generator, hosted at the Institute of Plasma Physics and Lasers (IPPL) of the Hellenic Mediterranean University (HMU) Research Centre, has previously been used for optical probing experiments of Z-pinch [14, 15, 16] and X-pinch wire configurations [17], and time-integrated X-ray spectroscopic measurements of the radiation produced by X-pinch loads have been performed [18]. Herein, a new analysis of time-resolved soft X-ray emission measurements is performed to provide a secure correlation with the optical probing results. Additionally, the use of the X-pinch configuration as an X-ray source for energies greater than 6 keV is characterized, and its applicability in X-ray radiography applications is evaluated.  
Our X-pinch device lies at the lower peak current range of X-pinch generators [19]. To the best of our knowledge, such a generator has not been used previously to deliver X-ray radiographs of biological samples, using photons in the range between 6 and 13 keV, produced by fast-rise-time (\(\geq\)1 kA/ns) X-pinch generators [20]. Furthermore, a reconstruction of the actual photodiode current profile procedure is adopted for time-resolved X-ray measurements for first time. This procedure allows for overcoming the limits of the \"slow\" response of the diodes and the noise. The compact tabletop X-pinch used for X-ray radiography is proven to be ideal for the detection of interior defects in biological samples.