Investigation of the ejected mass during high-intensity laser solid interaction for improved plasma mirror generation

The interaction of very intense and ultrashort laser pulses with solid targets is a topic that has attracted a large amount of interest in science and applications. This interest is boosted by the large progress made in the development of high repetition rate, high-power laser systems. With the significant increase in average power, there is concern about how to deal with ablated debris that may lead to contamination and damage during interaction experiments with solid targets. This issue is also highly relevant in experiments that include plasma mirrors. These are often employed to increase the contrast ratio of the intense laser pulse to unwanted laser pre-pulses from the amplifier chain and/or the background of amplified spontaneous emission. For this reason, the present work investigates the mass ejected from the target into vacuum for different conditions, particularly those present when plasma mirrors are introduced. The total amount of ablated mass can be reduced by making use of a temporally controlled plasma expansion that enhances the plasma mirror reflectivity. In this way, high intensity laser interaction experiments can be carried out with efficient and clean plasma mirrors significantly reducing the degradation of the laser optics and plasma diagnostics placed near the interaction.

Measuring Gravitational Effect of Superintense Laser by Spin-Squeezed Bose-Einstein Condensates Interferometer

In this article, we consider an extremely intense laser, enclosed by an atom interferometer. The gravitational potential generated from the high-intensity laser is solved from the Einstein field equation under the Newtonian limit. We compute the strength of the gravitational force and study the feasibility of measuring the force by the atom interferometer. The intense laser field from the laser pulse can induce a phase change in the interferometer with Bose-Einstein condensates. We push up the sensitivity limit of the interferometer with Bose-Einstein condensates by spin-squeezing effect and determine the sensitivity gap for measuring the gravitational effect from intense laser by atom interferometer.

Ultrasonic diagnostics of vascular complications after laser procedures

A clinical case of treatment of rosacea with a high-intensity laser at different stages, performed under control of high-resolution ultrasound (HRU), is presented. According to clinical guidelines, patients in the erythematous stage of rosacea (stage I) undergo selective coagulation of superficial vessels with a neodymium laser. Diagnosis and determination of the severity of the disease are carried out based on the presence of primary and secondary elements of the rash. There are no criteria for ultrasound assessment of the skin and its vascularization in patients with rosacea. During ultrasound examination after 4 laser procedures in B-mode, the dermis is heterogeneous due to hypoechoic papillary and hyperechoic reticular layers, without signs of infiltrative changes, in the color Doppler mapping mode there is a pronounced vascularization of the papillary dermis in the area of interest, represented by multiple vessels in contrast to single vascular structures seen on ultrasound after two laser treatments. According to the results of ultrasound examination, a more severe degree of the disease was diagnosed, which served as the basis for prescribing therapy with systemic retinoids. Clinical observation demonstrates the capabilities of ultrasound in planning laser procedures in order to reduce the risk of complications, their early diagnosis and monitoring of treatment if they occur.

Fifteen years of experience in plastic liquor fistulas using high-intensity laser radiation

Introduction. The need to close liquor fistulas as early as possible is associated with a high risk of intracranial complications. Certain difficulties in closing bone defects are due to the variability of the exact localization of the fistulous canal, the choice of the surgical approach, and the reliability of the plastic material. The literature describes various methods for eliminating basal liquorrhea, however, the advantage of none of them has not been proven, which determines the relevance of the search for new methods.Objective. Based on the analysis of long-term results, to study the efficiency of plastic closure of cerebrospinal fluid fistulas using high-intensity laser radiation.Materials and methods. An analysis of 15 years of experience in studying the effectiveness of plastic closure of cerebrospinal fluid fistulas in 126 operated patients with basal liquorrhea was carried out. The duration of the disease ranged from 2 months to 1.5 years. The main group consisted of 94 patients who underwent plastic closure of CSF fistulas using high-intensity laser radiation with a wavelength of 0.97 pm and a power of 2.5-3.5 W. The control group consisted of 32 patients who did not receive coherent laser radiation. In addition to the generally accepted methods of postoperative management, low-frequency ultrasonic cavitation irrigation of the operated cavities was used to accelerate the reparative processes in all patients.Results and discussion. The average follow-up period after surgery was over 13 years. When comparing the results of treatment, the main criterion for evaluating the effectiveness of the operation was the frequency of relapses. In 15 (12.3%) cases, a relapse was noted, of which 5 (3.71%) were patients in the main group and in 10 (8.32%) patients in the control group, who were closed by repeated surgeryConclusion. The clinical features of the basal liquorrhea include the variability in the localization of the fistulous canals, certain difficulties in their detection, a wide variety of plastic closure methods, and a high percentage of relapses. A prospective uncontrolled study has shown that this method of CSF fistula plasty using improves the efficiency of surgical treatment.

A Randomised-Controlled Clinical Study Examining the Effect of High-Intensity Laser Therapy (HILT) on the Management of Painful Calcaneal Spur with Plantar Fasciitis

Calcaneal spur and plantar fasciitis are the most common causes of plantar heel pain. There are many effective physical modalities for treating this musculoskeletal disorder. So far, the are no clear recommendations confirming the clinical utility of high-intensity laser therapy (HILT) in the management of painful calcaneal spur with plantar fasciitis. This study aimed to evaluate the effectiveness of HILT in pain management in patients with calcaneal spur and plantar fasciitis. A group of 65 patients was assessed for eligibility based on the CONSORT guidelines. This study was prospectively registered in the Australian New Zealand Clinical Trial Registry platform (registration number ACTRN12618000744257, 3 May 2018). The main eligibility criteria were: cancer, pregnancy, electronic and metal implants, acute infections, impaired blood coagulation, cardiac arrhythmias, taking analgesic or anti-inflammatory medications, non-experience of heel pain, or presence of other painful foot conditions. Finally, 60 patients were randomly assigned into two groups: study group (n = 30, mean age 59.9 ± 10.1), treated with HILT (7 W, 149.9 J/cm2, 1064 nm, 4496 J, 12 min), and placebo-controlled group (n = 30, mean age 60.4 ± 11.9), treated with sham HILT therapy. Both groups received ultrasound treatments (0.8 W/cm2, 1 MHz frequency, 100% load factor, 5 min). Treatment procedures were performed once a day, five times per week for three weeks (total of 15 treatment sessions). Study outcomes focused on pain intensity and were assessed before (M1) and after (M2) the treatment as well as after 4 (M3) and 12 (M4) weeks using the Visual Analogue Scale (VAS) and the Laitinen Pain Scale (LPS). According to VAS, a statistically significant decrease in the study group was observed between M1 and M2 by 3.5 pts, M1 and M3 by 3.7 pts, and M1 and M4 by 3.2 pts (p < 0.001). On the other hand, the control group showed a statistically significant decrease (p < 0.001) between M1 and M2 by 3.0 pts, M1 and M3 by 3.4 pts, and M1 and M4 by 3.2 pts. According to LPS, a statistically significant decrease in the study group was observed between M1 and M2 by 3.9 pts, M1 and M3 by 4.2 pts, and M1 and M4 by 4.0 pts (p < 0.001). On the other hand, the control group showed a statistically significant decrease between M1 and M2 by 3.2 pts (p = 0.002), M1 and M3 by 4.0 pts (p < 0.001), and M1 and M4 by 3.9 pts (p < 0.001). However, there were no statistically significant differences between the groups in VAS and LPS (p > 0.05). In conclusion, the HILT does not appear to be more effective in pain management of patients with calcaneal spurs and plantar fasciitis than the conservative standard physiotherapeutic procedures.

Towards ML-Based Diagnostics of Laser–Plasma Interactions

The power of machine learning (ML) in feature identification can be harnessed for determining quantities in experiments that are difficult to measure directly. However, if an ML model is trained on simulated data, rather than experimental results, the differences between the two can pose an obstacle to reliable data extraction. Here we report on the development of ML-based diagnostics for experiments on high-intensity laser–matter interactions. With the intention to accentuate robust, physics-governed features, the presence of which is tolerant to such differences, we test the application of principal component analysis, data augmentation and training with data that has superimposed noise of gradually increasing amplitude. Using synthetic data of simulated experiments, we identify that the approach based on the noise of increasing amplitude yields the most accurate ML models and thus is likely to be useful in similar projects on ML-based diagnostics.

Plasma guiding using a chaperone pre-pulse for stable wakefield generation

Achieving high quality electron beams in laser wakefield accelerators requires stable guiding of the intense driving laser pulse, which is challenging because of mode mismatching due to relativistic self-focusing. Here we show how an intense pre-pulse can be used to prepare the phase-space distribution of plasma electrons encountered by a trailing laser pulse so that it produces its own well-matched guiding channel, while minimising wakefield evolution. Controlling the propagation of high intensity laser pulses is an essential step in developing useful wakefield accelerators and compact radiation sources.