Cryogenic fuel targets (CFTs) open up the possibility for the practical implementation of in-line technologies in inertial fusion energy (IFE) systems for the production of clean fuel and electric and thermal energy. This article presents the results of a new cycle of research in the field of constructing a repeatable layering module (LM) for CFTs with high energy yield. The aim of the work is the mass production of CFTs, which is of particular scientific interest to the IFE community. The LM construction principle is based on the free-standing target (FST) method, i.e., the formation of a solid fuel layer inside free-standing and line-moving targets, proposed and developed at the Lebedev Physical Institute (LPI). This technology formed the basis of the LPI project for the development of a specialized LM for the low-cost in-line production of CFTs and their repeatable noncontact delivery to the focus of high-power laser facilities operating in a pulse-periodic mode.

Magnetic levitation technologies are studied as an innovative basis for developing contactless systems for delivering cryogenic targets to the laser focus of an ICF facility or future power plant. A necessary element of such systems is a special target carrier made of high-temperature superconductors (HTSC) with high vortex pinning. It is shown experimentally that an HTSC carrier in the form of an outer coating of the target makes it possible to completely eliminate mechanical friction during target acceleration due to its levitation in gradient magnetic fields. The prospects for further development of this direction in the area of creating HTSC nanostructured films and coatings are discussed.

Creation of an efficient system for the frequent delivery of cryogenic fuel targets (CFT) to the focus of a powerful laser facility is one of the key directions of research in inertial confinement fusion (ICF). The paper discusses prospects for the creation of a ring magnetic system based on the contactless acceleration of a levitating CFT carrier made of high-temperature type II superconductors (HTSC), up to specified injection velocities of 200–400 m/s. For this purpose, the temperature dependence of the magnetic moment of HTSC tapes in the range Δ T = 10–92 K was studied, prototype experiments on the acceleration of HTSC carriers at T ~ 80 K due to an external action on them with a frequency of ~1 Hz were carried out, and the speed for the stall of HTSC carriers from a circular trajectory were calculated. The calculation results are in good agreement with the experiment, which makes it possible to estimate the parameters of the ring magnetic accelerator for the operating temperature of the CFT injector T ~ 17 K. It is shown that the method proposed is promising for the creation of systems for noncontact delivery of CFT based on the principles of levitation and subsequent injection of CFTs into the center of the ICF reactor chamber at the required speed. The results of planning a new series of experiments are presented: acceleration of an HTSC carrier followed by injection of a surrogate target into the chamber of the GARPUN (LPI) KrF laser.

Nowadays, inertial confinement fusion (ICF) research related to noncontact positioning and transport of free-standing cryogenic targets is playing an increasingly important role in this field. The operational principle behind these technologies is the magnetic acceleration of the levitating target carrier (or sabot) made from Type-II, high-temperature superconductors (HTSCs). The physics of interaction among levitation, guidance and propulsion systems is based on a quantum levitation of high-pinning HTSCs in the mutually normal magnetic fields. This paper discusses current target delivery strategies and future perspectives to create different permanent magnet guideway (PMG) systems for ICF target transport with levitation. In particular, several PMG building options for optimizing both suspension and levitation of ICF targets using an HTSC-sabot will be analyzed. Credible solutions have been demonstrated for both linear and round PMGs, including the ones with a cyclotron acceleration process to realize high-running velocities of the HTSC-sabot for a limited magnetic track. Focusing on physics, we describe in detail the main aspects of the PMG building and the results obtained from computations and proof of principle experiments. High-pinning HTSC magnetic levitation promises a stable and self-controlled levitation to accelerate the ICF targets placed in the HTSC-sabots up to the required injection velocities of 200 m/s and beyond.

The development of a system for noncontact positioning and transport of cryogenic fuel targets (CFTs) is an important task in the inertial confinement fusion (ICF) program. In this paper, we investigate the possibility of constructing a levitation system for accelerating the CFT magnetic carrier along a superconducting tape guide made of HTSC materials.

ПОТОЧНОЕ ПРОИЗВОДСТВО КРИОГЕННЫХ ТОПЛИВНЫХ МИШЕНЕЙ ДЛЯ ЛАЗЕРНЫХ СИСТЕМ ИТСИ.В.Александрова, Е

An urgent issue in research of inertial confinement fusion (ICF) is the development of the scientific, engineering, and technological base to settle the problem of quality protection of the fuel layer during the high repetition rate delivery of a cryogenic fuel target (CFT) to the focus of a high-power laser facility or ICF reactor. A concept of the multilevel system of CFT protection developed at the Lebedev Physical Institute of the Russian Academy of Sciences is discussed. The concept includes possible ways of integration of the latest developments in the area of formation of the stable ultrafine fuel structure and also the application of external methods of CFT protection such as the (cryogenic and/or metallic) CFT external coatings, the profiling of a target nest inside the sabot (CFT carrier), and the noncontact CFT delivery using a hybrid accelerator based on the effect of quantum levitation of high-temperature superconductors in a magnetic field. The results obtained during the theoretical and experimental simulation made it possible to transfer from the stage of conceptualization to the stage of engineering implementation of the problem.

Creation of a delivery system based on noncontact positioning and transport of the cryogenic fuel targets represents one of the major tasks in a general program of inertial fusion energy (IFE) research. The purpose is to maintain the fuel layer quality during acceleration and injection of IFE targets at the focus of a powerful laser facility or IFE reactor. The program of the Lebedev Physical Institute (LPI) includes much development work on creation of different designs of the hybrid accelerators for IFE target transport with levitation. One of the main directions is an electromagnetic accelerator (EM-AC) + PMG system, where PMG is the permanent magnet guideway. The operational principle is based on quantum levitation of type-II high-temperature superconductors (HTSC) in the magnetic field. At the current stage, conceptual development of "EM-AC + PMG" hybrid accelerator is complete, and proof-of-principle experiments in mutually normal magnetic fields are made. This accelerator is a combination of the acceleration system (field coils generating the traveling magnetic waves) and the levitation system (PMG including a magnetic rail or magnetic track). The results obtained show that the HTSCs can be successfully used to maintain friction-free motion of HTSC sabots over the PMG, and also provide the required stability of the levitation height over the whole acceleration length due to the pinning effect. Additionally, using the driving body from MgB2 superconducting coils as a sabot component (critical current 5,000 A at magnetic induction 0.25 T) allows one to reach injection velocities of 200 m/s under 400 g at 5 m acceleration length.

A considerable attention has recently been focused on the issue of large target fabrication for inertial confinement fusion (ICF) research on MJ-class laser facilities. The targets require a condensed uniform layer of hydrogen fuel on the inside of a spherical shell. The fusion fuel inside the targets must have such a structure, which supports the fuel layer survivability under target injection and transport through the reactor chamber. Over the last two decades, the Lebedev Physical Institute (LPI), has been devising the structure-sensitive methods of forming high-quality hydrogen fuel with an isotropic structure (ultra-fine type of solid layers) to meet the requirements of implosion physics. A considerable anisotropy of HCP-phases of H-2 and D-2 (single crystal or coarse-grained crystalline layers) results in the layer degrading due to roughening of the layer surface before the target reaches the chamber center, or can result in the spherical-shock velocity dependence on the grain orientation. On the contrary, the ultra-fine solid layers have enhanced mechanical strength and thermal stability which is of critical importance for target fabrication, acceleration and injection. To meet the goal of ultra-fine solid layers formation, the LPI has constructed a piezo-vibration module, in which the couple "membrane & target" is driven by an input signal generated due to inverse piezoelectric effect during fuel cooling via the heat conductivity within vibrating targets. It allows one to modify the key experimental parameters (mechanical and thermal) for influencing the fuel microstructure and intensifying the creation of ultimate disordered structures with a large defect density, i.e., isotropic medium. In this report, the modeling results of the processes of cryogenic layer fabrication in the conditions of high-frequency mechanical influence are presented. The investigation is carried out to gain insight into the relation between the microstructure and bulk properties of the fusion fuel, and to fabricate this fuel with a given microstructure within ICF targets.

Многоуровневая система защиты криогенной мишени при её доставке в фокус мощной лазерной установки...

ФОРМИРОВАНИЕ УЛЬТРАДИСПЕРСНОГО ВОДОРОДНОГО СЛОЯ ПРИ ВНЕШНЕМ ВИБРАЦИОННОМ ВОЗДЕЙСТВИИ НА КРИОГЕННУЮ МИШЕНЬИ.В.Александрова 1 , А.А.Акунец 1 , Е

To provide continuous operation of a reactor based on inertial confinement fusion (ICF), the thermonuclear burn region should be refilled with fuel with a frequency of 1 million targets per day. The first stage in the target production is diffusion filling of polymeric (CH) shells with fuel gas which is deuterium (D2) or deuterium–tritium (DT) mixture. The results of simulation of filling reactor-scale CH-shells (Ø ~ 4 mm) to a pressure of ~1100 atm at 300 K in the mode with a constant pressure gradient are presented. Simple and two-layer shells of compact and porous polymers are considered. The problems of constructing an optimum DT-filling scheme avoiding CH-shell fracture due to tritium beta decay are discussed.

We present our results on utilization of the quantum levitation effect for HTSC samples (superconducting ceramics based on YBa2Cu3O7−x and SuperOx J-PI-12-20Ag-20Cu superconducting tapes) in magnetic fields of different configurations with respect to developing special carriers for hybrid systems of noncontact transport of cryogenic targets in ICF experiments. We implement the obtained results for developing and engineering of “HTSC-MAGLEV” delivery system to minimize the risk for damage of the fuel layer at the target acceleration and during target injection into the center of the ICF reaction chamber.

1 Федеральное государственное бюджетное учреждение науки Физический институт им.П.Н.Лебедева Российской академии наук, Москва, Россия 2 Национальный исследовательский ядерный университет «МИФИ», Москва, Россия 3 ООО «ЦЭ Интер РАО ЕЭС», Москва

The results of a series of experiments using a piezovibration formation module for producing cryogenic targets with a given fuel layer structure are presented.

It is proposed to use the HTSC quantum levitation phenomenon in magnetic fields of various configurations to develop the systems of contact-free positioning and transport of cryogenic fuel targets (CFTs) to the focus of a high-power laser installation or the IFE reactor. The results are presented of a large cycle of experimental studies using YBa2Cu3O7−x superconducting ceramics and permanent magnet guideways based on various combinations of permanentmagnets to develop “CFT-MAGLEV” delivery systems.

The results of experimental studies using SuperOx J-PI-12-20Ag-20Cu tape superconductors in developing capsule carriers for cryogenic systems of noncontact transport of targets for IFE are presented.

A challenge in inertial fusion energy (IFE) research is to deliver the target to the target chamber center at a high repetition rate. Therefore, the problem of target fabrication and delivery is focused on methods that scale to highly repeatable and cost-effective target production. In this paper, we investigate the possibility of using magnetic-levitation (maglev) transport systems for noncontact manipulation, positioning, and delivery of the cryogenic targets. We focus on the development of transport systems based on movement of high-temperature superconductors (HTSC) over a permanent magnet guideway (PMG). Active guidance is achieved using the HTSC ceramics YBa2Cu3O7− X and PMG, where an ordered motion is initiated by a special arrangement of the permanent magnets. At present, significant R&D programs are ongoing in order to fulfill the technical requirements and basic elements of the system’s operation as a maglev target accelerator. We present here the main results of this work along with recent results.