## 3 Target Delivery System
Firstly, a set of targets was aligned, resulting in a table of target coordinates and a corresponding set of target snapshots taken by the imaging system. Then, the target renewal was simulated by a sequence of triggers with repetition rate of 1 Hz. Target snapshots were recorded once the target was in position. Comparing the respective images corresponding to the individual targets, the estimated misalignment was evaluated as less than 10 \(\upmu\)m.  
Figure 2: The sequence of four trigger signals (blue) at 1 Hz repetition rate initiating the motion of the following targets. The orange signal corresponds to a reference output confirming that the new target is in the aligned position. The present configuration of the planar target delivery system demonstrates good ability of target refreshing at 1 Hz repetition rate in a real experimental run at TERESA target area [17]. The OAP with focal length of 330 mm (\(\approx\)f/3.7) allows to obtain a laser focal spot diameter of about 3.8 m of full width at half maximum. All targets rastered before the laser firing can keep their position with a repeatability better than 10 m over the whole laser shot sequence. During the operation of a 30-fs laser with 1 J energy on target (intensity around \(5\times 10^{19}\) W/cm\({}^{2}\)), no substantial damage on individual target frames, nor EMP-related issues, nor nuclear activation were observed after a complete run of about 1000 shots. Additionally, we have developed and tested a second type of fast target delivery system. The spiral tower is a concept of a target handling system, which allows work at high repetition rates (see Figure 4a). The device consists of a 1-cm-thick Al disk (10 cm diameter) where targets are fixed, a translation and a rotation stage for a motorized rototranslation movement, and two linear stages, one for tilt and one for z micrometer level adjustment. In addition, a linear stage allows adjustment of the height of the device according to the laser interaction point. Similar to the target tower described above, all parts of the device are made of vacuum compatible materials to avoid contamination inside the vacuum chamber. Figure 4: Picture presents (**a**) the spiral tower, used at high repetition rate; and (**b**) examples of irradiated Fe, Cu, and Sn target plates with dimensions 50 by 50 mm. Left figure represents a zoomed picture of the irradiated area of Fe target showing a typical spiral shape. Figure 3: Imaging of the target switching process between two laser shots acquired with monitoring system. Since the supporting disk is very thick, the device is used in experiments where only the backward plasma emission is of interest for the given experiment. Typically, the employed targets are mm-thick slabs. In contrast to the PTDS system, the number of interaction points is not fixed by the target holder. This device has been tested in single shot and at 1 and 10 Hz repetition rate, delivering thousands of shots continuously using the Bivoj laser (10 J max laser energy delivered in 5-10 ns pulse duration, working at the fundamental wavelength of 1032 nm) at the HiLASE laser center [5]. Dedicated software has been developed for motion control of the tower. It is possible to manually move every single motor or setting for a more complicated series of movements for multi-shot irradiation. A combination of translation and rotation allows the system to move in a spiral trajectory. Few irradiated targets are illustrated in Figure 4b, where the typical spiral shape is demonstrated. The distance between the subsequent interaction points on the target and the number of shots in the same position (if required by the user) can be preset according to the necessity of the experiment. The spiral tower demonstrated stable operation at repetition rates up to 10 Hz during the laser irradiation with stable ion shot-to-shot signal.