Techniques for enhanced restraint in magnetic fusion devices

Abstract

Techniques for initiating and maintaining a transport barrier within a magnetically confined plasma in a plasma fusion apparatus are disclosed. For an annular magnetic configuration, a characteristic region of a magnetic field may be created by generating an electric current within the plasma or otherwise establishing a characteristic region of the magnetic field. The location of the feature region may be controlled appropriately close to the inner wall of the plasma fusion device to allow a number of particles to be injected into the plasma at or within the feature region. The number of particles may increase the density of the plasma and create a density gradient within the feature region such that a transport barrier is formed at or within the feature region.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63 / 326,659, filed on April 1, 2022, which is incorporated herein by reference in its entirety.

[0003] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0004] This invention was made with Government support awarded by the Department of Energy under Grant No. DE-FG02-04ER54742. The Government has certain rights in this invention. Technical Field

[0005] The present disclosure relates to magnetic confinement of plasma. In particular, techniques for producing enhanced confinement of plasma in devices for fusion processes are described. Background Art

[0006] Nuclear fusion remains a focus of research into scalable energy sources. As the global demand for clean, renewable energy increases, so does the desirability of nuclear fusion as such an energy source. However, to date, nuclear fusion technology has not achieved a sustained reaction sufficient to produce more energy than is needed to operate a reactor.

[0007] In nuclear fusion, two atomic nuclei (e.g., deuterium or tritium) combine to form one atomic nucleus (e.g., helium), which generates large amounts of energy. In order for this reaction to occur, a plasma, or ionized gas, must be confined and heated to millions of degrees Celsius. Confinement is typically achieved using strong magnetic fields within the reactor, so that magnetic confinement keeps the reacting plasma away from reactor structures (e.g., chamber walls). The most successful reactor designs involve a doughnut-shaped vessel like a tokamak, in which the plasma is generated within a vacuum chamber and confined by a toroidal magnetic field.

[0008] In a tokamak or similar toroidal fusion reactor, plasma confinement is achieved by establishing a stable magnetic field within the reactor using several external field coils and generating currents within the plasma. Because the plasma is ionized, its constituent particles are charged and will tend to rotate tightly around the magnetic field lines in relatively small orbits. In essence, the plasma sticks to the field lines, but can easily move along them. The field generated in the reactor has both a toroidal (in the direction of the "ring" of the torus) component and a poloidal (in the direction of the "around" of the torus) component, resulting in a spiral magnetic field that passes through the interior of the reactor. The configuration of this magnetic field therefore includes nested toroidal magnetic surface regions that contain magnetic field lines that are closed and do not touch the inner surface of the reactor vessel. The plasma can then be suspended in the closed magnetic region for a long time without touching the surface of the reactor. However, there are several processes that allow the plasma to transport across the field lines and leave the confinement region, resulting in energy and particle losses in the area where fusion occurs. Therefore, improving the confinement of plasma by limiting the transport of energy and particles across the confinement field is a goal of contemporary research. Summary of the invention

[0009] One aspect of confined plasma is the presence of a "transport barrier," i.e., a steep gradient of density, temperature, and / or pressure of the plasma. A transport barrier indicates a weakening of one or more of the processes, resulting in instability of the confined plasma and transport of energy and particles out of the confinement region, including turbulent plasma flow. Depending on the configuration of the magnetic field, such weakening may be caused by velocity shear, magnetic shear, or similar mechanisms. Velocity shear has long been considered the primary mechanism for suppressing turbulent transport processes in confined plasmas. However, fusion operating schemes employing low-speed shear are possible and may be essential for further progress. Therefore, there is a need for methods of controlling the formation (e.g., location, duration, extent) of transport barriers.

[0010] Embodiments of the present disclosure relate to improving the confinement of plasma in a fusion device. Plasma can be confined by a magnetic field, which can be generated and manipulated by applying an electric current outside the plasma (e.g., in an external coil) or an electric current inside the plasma (e.g., an electric current in the plasma itself). A characteristic region of a confined magnetic field with specific properties can be generated. By injecting particles into the plasma at or inside a characteristic region of the magnetic field, a transport barrier can be induced that reduces the transport of plasma particles and energy from the confinement region of the magnetic field, thereby improving the confinement of the plasma. This transport barrier can be maintained by subsequently injecting additional particles.

[0011] One embodiment is directed to a method that includes generating a characteristic region of a magnetic field that confines plasma in a plasma confinement apparatus and injecting a number of particles into the plasma at or within the characteristic region.

[0012] In various examples, the characteristic region can be defined by a negative magnetic shear region, a low magnetic shear region, a large Shafranov offset region, a specific shape of the magnetic surface of the magnetic field that confines the plasma (where the magnetic disturbance is resonant), or any combination of these defining features. In some examples, the characteristic region can be generated by generating a current in the plasma that is parallel to the magnetic field at the characteristic region. According to certain examples, injecting this number of particles at or inside the characteristic region can generate a transport barrier. The transport barrier can be characterized by a large pressure gradient of the plasma. Resonant magnetic disturbances induce the transport of particles and heat, and causing these disturbances in the characteristic region helps to control the pressure gradient there. In some embodiments, this is useful for increasing the width of the transport barrier and avoiding magnetohydrodynamic instability. The transport barrier can be generated at a position of about 70% of the secondary radius of the plasma confinement device. In some examples, the transport barrier can be generated at a position of about 80% or about 90% of the secondary radius of the plasma confinement device. In some examples, the number of particles can include fusion fuel particles, including deuterium and / or tritium. In some examples, the number of particles may include impurity particles including carbon, silicon, a rare gas, or an element having an atomic number Z less than 21.

[0013] Another embodiment is directed to a second method that can include generating a characteristic region of a magnetic field that confines a plasma, injecting a first number of particles into the plasma at or within the characteristic region, and injecting a second number of particles into the plasma at or within the characteristic region. The first number of particles can be injected at a first time and for a first duration, and the second number of particles can be injected at a second time and for a second duration.

[0014] In various instances, the characteristic region can be defined by a negative magnetic shear region, a low magnetic shear region, a large Shafranov offset region, a specific shape of the magnetic surface of the magnetic field that confines the plasma, the location of the magnetic perturbation resonance, or any combination of these defining features. In some instances, the first number of particles may include at least a portion of impurity particles. In several instances, the second number of particles may include impurity particles, fusion fuel particles, and / or a mixture of impurity particles and fusion fuel particles. According to certain instances, both the first number of particles and the second number of particles may be injected at a time-averaged rate. The time-averaged rate of particle injection for the second number of particles may be less than the time-averaged rate of injection for the first number of particles. In some instances, the first number of particles may include a first portion of fusion fuel particles, and the second number of particles may include a second portion of fusion fuel particles, wherein the second portion is larger than the first portion.

[0015] Another embodiment relates to a system that may include a plasma confinement device, a particle injector, and a controller. The controller may have one or more processors and one or more memories storing computer executable instructions that, when executed by the one or more processors, cause the system to adjust a current of a plasma confined by a magnetic field within the plasma confinement device to produce a characteristic region of the magnetic field, and to use the particle injector to inject a certain number of particles into the plasma at or within the characteristic region, thereby forming a transport barrier at or within the characteristic region.

[0016] In some examples, the plasma confinement device may be a tokamak, a stellarator, or a toroidal pinch device. In several examples, the particle injector may be configured to inject the number of particles with high-speed particles (which may include a portion of cryogenically frozen particles) or with a magnetically confined plasma (which may be a compact toroid). In some examples, the number of particles may be a first number of particles injected at a first time and lasting for a first duration. One or more memories of the controller may store additional instructions, which, when executed, cause the system to further use the particle injector to inject a second number of particles at a second time and last for a second duration, and the second number of particles maintains the transport barrier during the second duration. According to certain examples, the first number of particles may include impurity particles, and the second number of particles may include fusion fuel particles or a mixture of fusion fuel particles and impurity particles. In some examples, the first number of particles may include a first portion of fusion fuel particles, and the second number of particles may include a second portion of fusion fuel particles, wherein the second portion is larger than the first portion. In some examples, the time-averaged rate of particle injection for the second number of particles may be less than the time-averaged rate of injection for the first number of particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1A and 1B is a cross-sectional schematic diagram of an example plasma confinement system according to several embodiments.

[0018] Figure 2 is a cross-sectional view of a confined plasma having a feature region for forming a transport barrier according to at least one embodiment.

[0019] Figure 3 is a simplified illustration of a toroidal magnetic configuration with a characteristic region for forming a transport barrier according to at least one embodiment.

[0020] Figure 4 is a simplified diagram of a plasma confinement system for creating a transport barrier at a characteristic region of a confining magnetic field in accordance with at least one embodiment.

[0021] 5 is a drawing depicting an example mode of operation of a plasma confinement device.

[0022] Figure 6 is another graph depicting example temperature gradients for a confined plasma exhibiting a generated transport barrier in accordance with at least one embodiment.

[0023] Figure 7 is a simplified diagram of an example method for creating a feature region in a magnetic field that confines a plasma, according to at least one embodiment.

[0024] Figure 8 is another simplified diagram of an example method for inducing a transport barrier with a first number of particles and maintaining the transport barrier with a second number of particles in accordance with at least one embodiment.

[0025] Fig. 9 is another simplified diagram of an example method for creating a transport barrier at a feature region of a magnetically confined plasma in accordance with at least one embodiment. DETAILED DESCRIPTION

[0026] The technology described herein relates to systems and methods for controlling the formation of a transport barrier (TB) within a magnetically confined plasma. In particular, the technology includes manipulating the confined magnetic configuration to establish a field region with a specific characteristic (e.g., negative magnetic shear or reduced magnetic shear), and then injecting a certain number of particles (e.g., fusion fuel particles) at or inside the characteristic region to form a transport barrier. The increased density of the injected particles can lead to the formation of a transport barrier (e.g., a steep radial gradient of plasma temperature, density, and / or pressure). The transport barrier can be formed at or near the characteristic region. By controlling the location where the characteristic region is formed, the location of the resulting transport barrier can also be controlled, thereby allowing the formation of a TB at a location that is favorable for the confinement of the plasma.

[0027] Existing plasma confinement devices for fusion applications typically operate in one of a variety of confinement modes, thereby forming TBs at different locations. As a specific example (refer to FIG. 5 ), a tokamak (and stellarator) can be operated in a high confinement mode (H mode, such as H mode 504 of FIG. 5 ), thereby producing an internal TB (ITB, such as ITB 508, i.e., a TB away from the inner wall of the device) and an edge TB (e.g., edge TB 510). The H mode can be distinguished from a low confinement mode (L mode, such as L mode 506) that existed before the confined plasma was strongly heated. It is generally believed that the transition from the L mode to the H mode is caused by the suppression of turbulence in the plasma. The ITB in the H mode can define an internal "core" region (e.g., core region 502) of the plasma, where sufficient temperature and density are achieved to support the fusion process. The edge TB in the H mode is usually close to the inner wall of the reactor, where the magnetic field lines are open, and the particle flux is unconstrained and may hit the wall and other structures.

[0028] As described above, TBs may form when certain plasma instabilities (e.g., turbulent plasma processes) are weakened or suppressed. These instabilities can be characterized by one or more modes of the system, including ion temperature gradient (ITG) modes, electron temperature gradients, trapped electron modes (TEM) modes, and / or coupling between one or more modes. In general, plasma instabilities are caused by "deflections" of particles across magnetic field lines. Several deflections are characteristic in plasmas and are related to both the geometry of the magnetic field (e.g., gradient, curvature, etc.) and the dynamics of the charged particles (ions and electrons). Deflections can include Offset, Taking the ITG mode as an example, grad-B shift and curvature shift are the mechanisms of plasma instability driven by the ITG mode: the grad-B shift speed is This depends on the kinetic energy of the particle, which in turn depends on the particle's temperature. If the electric field is consistent, the particles in the hotter region of the ITG will be deflected more than the particles in the colder region, resulting in charge separation, and the resulting electric field will drive This turbulence process can be to suppress shear in the flow.

[0029] However, for larger geometries, velocity shear scales less well, so the suppression of turbulent processes becomes weaker. Therefore, velocity shear is unlikely to be sufficient to provide adequate confinement for plasmas in larger reactors.

[0030] Turbulent transport processes may also be suppressed in the presence of magnetic shear. For a toroidal magnetic configuration (e.g., in a tokamak), the magnetic shear of the field can be defined as the radial gradient of the "rotational transformation" ι, which is a measure of the number of poloidal crossings the field lines make for each toroidal crossing of the line (essentially, how many helical twists the field lines make as they travel around the torus). Mathematically, the magnetic shear force is defined as Where r is the radial coordinate from the center of the annular cross-section of the torus. In regions where the radial gradient of ι is large (e.g., the poloidal "twist" is larger as r increases), magnetic shear may appear negative, which can be produced by currents in the plasma parallel to the magnetic field in this region. Negative magnetic shear is associated with the suppression of instabilities caused by the curvature of the magnetic field (e.g., curvature offset). In some instances, low magnetic shear may be a region where s < 0.3. More generally, a region of curvature instability can be characterized by a length parameter such that the length parameter is small along the magnetic field (e.g., less than a characteristic distance). In other words, the destabilizing curvature offset velocity has a destabilizing sign, where the perturbation of the steep gradient in the curvature offset-driven plasma grows over a distance of the length parameter.

[0031] Turbulent transport processes may also be suppressed in the presence of a large Shafranov shift. The Shafranov shift is an outward radial displacement of the center of a flux surface with a minor radius r induced by plasma pressure or pinch forces. For the purposes of this disclosure, the Shafranov shift can be approximated by the parameter Definition, where MKSA units are used, where is the inverse of the rotation transformation, where R is the distance from the approximate rotation axis 112 for the magnetic geometry in FIG. 1 , where B is the total magnetic field strength, and μ0 is the magnetic permeability of free space (=4π×10 -7 Newtons per ampere squared). For example, a large value of the Shafronov shift may be α > 3. A large Shafranov shift and negative or reduced magnetic shear may act independently to reduce turbulence, but may also act together and achieve greater reductions.

[0032] An external coil (e.g., a central solenoid in a tokamak) can be used to induce currents in a confined plasma by supplying a varying current. For example, a central solenoid can be used to induce a circular current in a plasma by applying a linear ramp current to the solenoid. By configuring the geometry of the external coil and the supply current, currents in a confined plasma can be generated at specific locations, with the orientation of the currents being primarily consistent with the magnetic field at these locations. The induced currents can then generate appropriate magnetic shear, thereby forming characteristic regions suitable for initiating and maintaining ITBs.

[0033] TBs can be initiated in a variety of ways. As in the case of H-mode confined plasmas discussed above, TBs can form when a critical heating threshold of the core plasma is exceeded. The initial plasma can be generated using radio frequency discharges, microwave discharges, neutral beam heating, etc. Once ionized and confined, the plasma can be heated by ohmic heating (from induced currents), by compressive confining magnetic fields (adiabatic), neutral beam injection, and / or combinations of these and similar mechanisms.

[0034] Another method of inducing TB and the principle of the present disclosure is to inject particles into a confined plasma. Particles (e.g., fusion fuel particles, impurity atom particles) can be injected into a confined plasma to increase the local density gradient. Due to the conservation constraints on the plasma system, such injection into a confined plasma may induce a sustainable TB. TB can be formed at a location where the magnetic configuration of the confining magnetic field has specific characteristics (e.g., negative magnetic shear, large positive magnetic shear, reduced magnetic shear, large Shafranov shift, etc.).

[0035] Due to the dynamic processes within the confined plasma, it may not be feasible to inject particles (e.g., particles) deep into the core region. For example, a particle launched from outside the confined region at a speed of 1 km / s may only penetrate 20 cm of the confined region before ionizing and disintegrating. Therefore, a characteristic region of the magnetic field formed too close to the center of the confined region will prevent the deposition of the injected particles in that region. Similarly, the ITB associated with the typical operating mode of a fusion reactor is formed at a position too far from the outside of the confined plasma so that the formed mode cannot be maintained by particle injection. In addition, the edge TB of the H-mode operating scheme produces significant instabilities near the edge of the confined region, where the edge TB repeatedly weakens and allows plasma particles and energy to escape to the open field region of the reactor and deposits a large amount of energy into the walls and equipment of the container. The technology disclosed in the present invention solves many of these problems by allowing the formation of a characteristic magnetic region close enough to the outside of the confined plasma region to allow the injected particles to initiate and maintain the TB.

[0036] The basis of the technology disclosed herein is to recognize the basic physical constraints of the dynamics of the plasma process occurring in the reactor. Generally, the existence of a large gradient like TB will become a large source of free energy for the system, thereby driving various instabilities, thereby reducing or eliminating the gradient. However, as described above, TB can be formed in a magnetically confined plasma when turbulent processes are suppressed. The main constraint that allows the suppression of turbulent processes is that the turbulent transport is bipolar, so the net charge flux caused by turbulence in the plasma is zero (i.e., the turbulent process does not produce an ion flux that is unbalanced with the electron flux). Since steep density gradients tend to drive ion charge fluxes rather than electron charge fluxes, flux constraints can prevent strong instabilities from occurring, because the transport generated by such instabilities cannot meet the conditions of bipolar transport. If the necessary conditions for bipolar transport are not met, instability will not occur. If the bipolar constraint cannot be met, the free energy in the steep gradients of density and temperature cannot be used for instability. Turbulence is thus suppressed. This observation, combined with the formation of specific regions of confined magnetic geometry, allows the injected particles to form both sustainable temperature and density gradients at specific regions, thereby forming TBs with beneficial properties for large-scale fusion reactions.

[0037] The present technology has many advantages over the methods known in the prior art. By controlling the generation of characteristic regions of magnetic geometric structures, characteristic regions can be formed at suitable locations to allow particles to be injected into the region. This position can allow TB to form farther from the center of the confinement region, thereby forming a larger and more stable core plasma region, where fusion reactions can occur, thereby improving fusion output power and better confining larger-scale reactors. The characteristic region can also be formed at an appropriate distance from the inner wall of the reactor vessel, thereby allowing TB to form farther away from the edge region, and limiting or eliminating the existence of other modes that strongly interact with the physical equipment (e.g., walls, diverters, limiters, probes, etc.) of the reactor vessel. Since the generated TB is farther from the center of the confinement region, additional particles can be injected into the region outside the TB to maintain the TB (e.g., maintain a density gradient) without degrading or destroying the TB.

[0038] Now turning to the attached figure, Figure 1A 1 is a schematic cross-sectional view of an example plasma confinement system 100 according to at least one embodiment. The plasma confinement system 100 may include a plasma confinement device 101. The plasma confinement device 101 may be an annular device that is axially symmetric about a central axis 112. Figure 1AAs depicted, plasma confinement device 101 may have a D-shaped cross-section, similar to many tokamak designs. Other cross-sectional shapes may also be employed, including circular, elliptical, etc. In addition, other configurations of toroidal confinement devices are contemplated, including stellarators, spherical magnets, toroidal pinch devices (e.g., reverse field pinches), etc.

[0039] The plasma confinement device 101 may have a wall 110 to provide a physical boundary for the interior of the device. The interior volume may be a vacuum chamber suitable for supporting the ionized gas or plasma required for fusion. The plasma confinement device 101 may have a major radius 114 defined from a central axis 112 to the center of the interior of the annulus. Similarly, the interior may have a minor radius 116 defined from the center of the interior to the inner surface of the wall 110.

[0040] An appropriate magnetic field may be generated within the volume to suspend and confine the plasma within the plasma confinement device 101. The magnetic field may be generated by one or more external coils ( Figure 1A The plasma confinement device 101 is provided with an external coil (not shown) including a central solenoid, one or more toroidal field coils, one or more poloidal field coils and / or one or more additional coils to generate a magnetic field inside the plasma confinement device 101. In some embodiments, one or more of the external coils may be configured to inductively couple with the suspended plasma to drive a current within the plasma. The plasma current may then generate a corresponding magnetic field within the plasma confinement device 101. For example, a central solenoid may be used to generate a varying external field that couples to the toroidal confined plasma and generates a toroidal current in the plasma. The toroidal current may then generate a poloidal magnetic field within the plasma confinement device. The poloidal magnetic field may then be the poloidal component of the resulting magnetic field that suspends and confines the plasma. The following is about Figure 2 and 3 More details are provided about the magnetic geometry in the toroidal confinement device.In other embodiments, the external coil can generate a resonant magnetic disturbance, ie, a magnetic disturbance that resonates in the plasma.

[0041] For the plasma confinement device 101 having a toroidal configuration, the magnetic field generated inside the confinement device 101 can be divided into two regions corresponding to the properties of the magnetic flux. The two regions can be separated by a dividing line 104, which defines a boundary between a closed magnetic flux region (e.g., a closed magnetic field line) surrounded by the dividing line 104 and an open magnetic flux region (e.g., an open magnetic field line) outside the dividing line 104. Figure 2 Provides more details on the internal magnetic field geometry.

[0042] The interior of the closed field region defined by the dividing line 104 may be the core plasma region 102, where the temperature and pressure may reach sufficiently high values ​​to initiate fusion reactions. The surface formed by the closed magnetic field lines is called a magnetic surface. The heating of the core plasma region 102 may be achieved using ohmic heating (e.g., induced currents in the plasma), RF discharges, microwave discharges, adiabatic compression (e.g., compressing confined magnetic fields), neutral beam injection, and other similar methods. Since particles and energy may diffuse across the field lines via transport processes (e.g., turbulent transport), it may be necessary to maintain strong confinement by limiting the transport processes so that the plasma remains at a sufficiently high temperature to maintain a fusion reaction for a long time.

[0043] In order to improve the plasma confinement in the core plasma region 102, the plasma confinement system 100 can generate a transport barrier (TB). The particle injector 106 can be configured to inject a certain number of particles into the confined plasma at or inside the characteristic region 108. The characteristic region 108 can be a magnetic field region of confined plasma, which has a geometric structure or other characteristic parameters suitable for establishing a TB. In some embodiments, the characteristic region 108 can be a region with low magnetic shear or a region with negative magnetic shear in the magnetic field. In other embodiments, the characteristic region 108 can be a region of strong Shafranov shift. In other embodiments, the characteristic region can be a region where the magnetic surface of the magnetic field has a specific shape, which is conducive to the formation of a transport barrier. In other embodiments, the characteristic region can be a place where the magnetic disturbance resonates. Although in Figure 1A Although depicted as a rectangle in FIG. 1 , the characteristic region 108 may be radially defined to form a radial layer substantially aligned with the flux surface of the confining magnetic field. In some embodiments, the characteristic region 108 may be located outside the core plasma region 102 (eg, farther from the central axis 112).

[0044] Figure 1B Another example of a plasma confinement system 100 is depicted. The feature region 108 can be located inside the plasma confinement device 101 (eg, closer to the central axis 112). Similarly, the particle injector 106 can also be located inside the plasma confinement device.

[0045] Establishing the characteristic region 108 may include generating a current within the confined plasma. The current may be parallel to the magnetic field at the location where the current is generated, thereby generating a magnetic shear region (e.g., negative magnetic shear, reduced magnetic shear, etc.) at the characteristic region 108. In some embodiments, the current that forms the characteristic region 108 may not pass through the characteristic region (e.g., the current density generated in the characteristic region is very small). The current may be generated by one or more external coils, which may change the shape of the magnetic surface. In other embodiments, the characteristic region may have a strong Shafranov shift.

[0046] Once the characteristic region 108 is established, a certain number of particles can be injected at or inside the characteristic region using the particle injector 106. The "inside" of the characteristic region 108 refers to being located deeper inside the core plasma 102, closer to the center of the core plasma, where the minor radius 116 is smaller. This number of particles can increase the density at and / or inside the characteristic region and form a density gradient within the characteristic region 108. As described above, the density gradient can form a TB via physical confinement in the confined plasma system. In some embodiments, the particle injector 106 can be configured to inject a second number of particles into the characteristic region 108 after the TB is established. The second number of particles can maintain the duration of the transport barrier longer than the duration usually allowed by the self-organization process of the confined plasma. In various embodiments, the particle injector 106 can be configured to inject the number of particles with particles (e.g., cryogenically frozen particles), particle beams, compact magnetic confinement plasma (e.g., a small spherical plasma gun), gas flow or other similar delivery methods. The particles used to induce the TB may be different from the particles used to maintain the TB. For example, the particles used to initiate the TB may include a certain proportion of "impurity" particles, while the particles used to sustain the TB may be entirely fusion fuel particles, or only a smaller proportion of impurity particles. Impurity particles with higher atomic numbers (higher Z values) can increase the density gradient and create stronger confinement for diffusion within the confined plasma, and thus may be more effective in initiating the TB.

[0047] For nuclear fusion reactors, fusion fuel is mainly deuterium and / or tritium, which may be the main component of confined plasma. Sometimes, as in the case of the fusion device ITER, there is an operational test phase in which the plasma is mainly composed of helium or protons. Strictly speaking, they are not fusion fuels; however, they are intended to play the role of fusion fuels to test plasma dynamics. Therefore, as used in this disclosure, helium and protons can also be regarded as fusion fuels because they play the same role as fusion fuels in testing plasma behavior, and TB formation is an important aspect of plasma behavior that can be tested in this operational phase. Impurity particles can be any other kind of ions other than fusion fuels, or ions that act as fusion fuels, including but not limited to lithium, neon, carbon, nitrogen, silicon, and other elements with atomic numbers Z=3 or Z>3. The number of particles injected by the particle injector 106 can include fusion fuel particles, impurity particles, or any combination of fusion fuel particles and impurity particles. In some embodiments, the composition of this number of particles may change over time depending on the type of particles desired at or within the characteristic region to maintain the TB and assist in the confinement fusion process.

[0048] Figure 2 FIG. 2 is a cross-sectional view of a confined plasma in a plasma confinement device 200 having a feature region 208 for forming a transport barrier according to at least one embodiment. The plasma confinement device 200 may be Figure 1A An example of a plasma confinement device 101 of the invention is shown in FIG. The plasma confinement device 200 may have an inner wall 204 defining an interior volume of the device in which a confining magnetic field may be established.

[0049] As described above, the magnetic field can be represented by the dividing line 202 ( Figure 1A The open magnetic field lines (e.g., Figure 2 The dashed lines in the demarcation (e.g., the dashed lines in the demarcation) may terminate on the surface of the plasma confinement device 200, which may include an inner wall 204, a diverter, a restrictor, or other device. The closed field lines inside the demarcation may form a circularly nested constant magnetic flux surface, referred to as a magnetic surface. The magnetic surface (e.g., the solid lines inside the demarcation 202) has field lines that typically "twist" the polar direction as they are transported along the inner ring of the plasma confinement device. As the plasma particles are ionized, the particles will tend to be bound ("stick") to the closed field lines in small gyroscopic orbits, allowing the particles to move relatively freely along the field lines, but move relatively slowly when crossing the field lines.

[0050] A characteristic region 208 of a magnetic field may be generated at a certain location inside the plasma confinement device 200. The characteristic region 208 may be Figure 1AAn example of a characteristic region 108 described herein. As with characteristic region 108, characteristic region 208 may have a radial orientation and shape such that characteristic region 208 is approximately aligned with a magnetic flux surface in a closed field region. In some embodiments, characteristic region 208 may be an area of ​​low magnetic shear, reduced magnetic shear, or negative magnetic shear. Generating characteristic region 208 may include generating a current parallel to a magnetic field in a plasma at or near characteristic region 208. In some other embodiments, the characteristic region may have a large Shafranov shift. In other embodiments, the characteristic region may be an area of ​​a magnetic field magnetic surface having a particular shape that facilitates the formation of a transport barrier. In other embodiments, characteristic region 108 may be a place where a magnetic disturbance resonates.

[0051] The characteristic region 208 may be created at a distance 206 from the boundary line 202 of the plasma confinement device 200. In some embodiments, the distance 206 may be a radial distance from the center of the annular cross-section of the plasma confinement device 200 (e.g., Figure 1A 10% of the minor radius 116 of the plasma confinement region). Thus, the feature region 208 may be formed at a location close to the boundary 202, but not close enough to form a final transport barrier, thereby causing instabilities near the edge of the plasma confinement region (e.g., edge localized modes). The 10% distance value from the boundary 202 is provided only as an example; other locations of the feature region 208 are also contemplated that would provide locations suitable for forming a transport barrier according to the present disclosure.

[0052] Figure 3 is a simplified diagram of a toroidal magnetic configuration 300 having a characteristic region 308 for forming a transport barrier according to at least one embodiment. The characteristic region 308 may be Figure 2 The characteristic area 208 or Figure 1A An example of a feature region 108 .

[0053] exist Figure 3 In the simplified geometry of FIG. 3 , the magnetic confinement region 302 includes a poloidal magnetic field 304 along a toroidal surface and a toroidal magnetic field 306. Therefore, the resulting total magnetic field includes spiral magnetic field lines that twist along the direction of the poloidal field 304 while following the toroidal magnetic field 306. The poloidal magnetic field 304 can be generated by an induced current in the plasma that is parallel to the toroidal magnetic field 306.

[0054] To generate the feature region 308, a current 310 may be generated in the magnetic confinement region 302. The current 310 may be parallel or substantially parallel to the magnetic field in the feature region 308. The current 310 may generate another contributing component (e.g., an additional poloidal field) to the magnetic field at the feature region. For example, the current 310 may generate an additional poloidal field, causing the gradient of the rotational transformation to become larger and causing the magnetic shear in the feature region to become negative.

[0055] Figure 4 4 is a simplified diagram of a plasma confinement system 400 for generating a transport barrier at a characteristic region 408 of a confining magnetic field according to at least one embodiment. The plasma confinement system 400 may be a plasma confinement system 400 as described above with respect to FIG. Figure 1A 1. The plasma confinement system 400 may include a plasma confinement device 404, shown here in cross-section. The plasma confinement system 400 may also include a particle injector 406 and a controller 410. The particle injector 406 may be Figure 1A An example of a particle injector 106 .

[0056] and Figure 2 Similarly, the magnetically confined plasma in the plasma confinement device 404 can be suspended in a closed magnetic flux region defined by the boundary 402, thereby creating a confinement region, which can in turn include a core plasma region (e.g., Figure 1A The core plasma region 102 of the confinement region. A characteristic region 408 of a confined magnetic field can be generated at an appropriate position within the confinement region. The characteristic region 408 can be formed close enough to the particle injector to allow a certain number of particles to be deposited at or inside the characteristic region 408 and to generate a sufficient density gradient to support the formation of a transport barrier (TB). This deposition can be achieved by ionizing a large number of neutral particles from the injector at the location of the characteristic region or inside the characteristic region. Again, the "inside" of the characteristic region can refer to a region closer to the plasma core, and secondly, a smaller radius than the characteristic region 408.

[0057] The controller 410 may be any suitable controller or control system configured to operate the particle injector 406. The controller 410 may include one or more processors and one or more memories configured to store computer executable instructions that may cause the particle injector 406 to inject a large number of particles into a confinement region (e.g., a feature region 408 or its interior) of a confined plasma in the plasma confinement device 404. The controller 410 may be configured to perform any suitable number of operations to perform the techniques of the present disclosure. In some embodiments, the controller 410 may be configured to receive one or more signals from one or more other components (e.g., sensors, probes, detectors, power supplies, etc.) of the plasma confinement system 400. The controller 410 may be configured to use the received signals to modify one or more operations under its control. For example, the controller 410 may receive a signal corresponding to a gradient (e.g., a temperature gradient) measured at a certain location (e.g., a feature region 408). The signal may indicate that the formed TB is weakening and that additional particles need to be injected to maintain the TB. Based on the signal, the controller 410 may respond and inject an additional number of particles to maintain the TB. Other parameters (eg, type of particles to be injected, duration between injections, etc.) may be similarly modified based on the received signal.

[0058] In some embodiments, controller 410 may also be configured to output control signals to one or more other components of plasma confinement system 400. For example, controller 410 may send signals to control current used to create a feature region (eg, feature region 408).

[0059] 5 is a plot 500 depicting an example operating mode of a plasma confinement device. The plot depicts arbitrary plasma pressure versus normalized radius r / a, where r is the radial coordinate from the center of the annular section of the plasma confinement device and a is the minor radius (e.g., Figure 1A 116 in the secondary radius). As previously described, the tokamak can be operated in a high confinement mode (H mode) 504, resulting in an internal transport barrier (ITB) 508 and an edge TB 510. The H mode can be distinguished from the low confinement mode 506 (L mode) that exists before the confined plasma is strongly heated. It is generally believed that the transition from L mode to H mode is caused by the suppression of turbulence in the plasma. The ITB in the H mode can define the inner "core" region 502 of the plasma, where sufficient temperature and density are achieved to support the fusion process. The edge TB 510 in the H mode is generally close to the inner wall of the reactor, where the magnetic field lines are open and the particle flux is unconstrained and may hit the walls and other structures.

[0060] As depicted in FIG5 , ITB 508 may be present in an interior region relatively far from the walls of the plasma confinement device (denoted as r / a=1). The location of ITB 508 limits the size of core region 502. In addition, if the core region 502 is to be located in a characteristic region of the magnetic field (e.g., Figure 1A If an ITB 508 is generated in a feature region 108 , the location of the ITB 508 may be too far from the particle injector, so that the particles cannot reach the location intact.

[0061] Figure 6 600 is another plot depicting an example temperature gradient for a confined plasma exhibiting a generated transport barrier 608, according to at least one embodiment. Plot 600 depicts ion temperature 602 (in arbitrary units) versus normalized radius. Typical values ​​for ion temperature and electron temperature for current confinement schemes are approximately 17 keV and 7 keV, respectively; higher values, particularly ion temperature, may be achieved in devices with improved confinement according to embodiments of the present disclosure.

[0062] The gradient of ion temperature 602 may occur in a region corresponding to transport barrier 608. Transport barrier 608 may occur at a characteristic region of the magnetic field that confines the plasma, which region may be similar to the characteristic regions described herein. Transport barrier 608 may be located at a distance 606 from the inner wall of the plasma confinement device. Distance 606 may be such that the gradient is formed at an appropriate location so as to be maintained by the injection of particles.

[0063] Figure 7 is a simplified diagram of an example method 700 for creating a feature region in a magnetic field that confines a plasma according to at least one embodiment. The method 700 may be performed by a plasma confinement system (e.g., Figure 1A The plasma confinement system 100, Figure 4 The method 700 is performed by one or more components of the plasma confinement system 400 of the present invention. The method 700 is illustrated as a logical flow diagram, where each operation represents a series of operations that can be implemented by hardware, computer instructions, or a combination thereof. In the context of computer instructions, an operation represents a computer executable instruction stored on one or more computer readable storage media, which when executed by one or more processors performs the operation. For example, Figure 4 The controller 410 or a similar computing system within the plasma confinement system. In general, computer executable instructions include routines, programs, objects, components, data structures, etc. that perform specific functions or implement specific data types. The order in which the operations are described should not be construed as a limitation, and any number of the described operations may be omitted or combined in any order and / or in parallel to implement the process.

[0064] Some or all of method 700 (or any other process described herein, or variations thereof, and / or combinations thereof, e.g., Figure 8 Method 800, Fig. 9 The method 900 may be performed on one or more computer systems (e.g., Figure 4 The computer system may be configured with executable instructions and implemented as code (e.g., executable instructions, one or more computer programs, or one or more applications) that is executed together on one or more processors, by hardware, or a combination thereof. The code may be stored on a computer-readable storage medium (e.g., one or more memories of a computer system), for example in the form of a computer program including multiple instructions executable by one or more processors. The computer-readable storage medium may be non-transitory.

[0065] Method 700 may begin at block 702, where a feature region may be created in a magnetic field that confines a plasma. The magnetic field may be in a plasma confinement device (e.g., Figure 1A The characteristic region may be characterized by negative magnetic shear, reduced magnetic shear, large Shafranov shift, a specific flux surface shape, or other similar features of the magnetic field or a combination of these features. The characteristic region may be generated by generating an electric current in a plasma confined by a magnetic field. The electric current may be parallel or substantially parallel to the magnetic field at the location of the characteristic region. The electric current may be generated by one or more external coils that may be inductively coupled to the plasma, or by radio waves generated outside the plasma and absorbed in the characteristic region, or by a neutral particle beam, or by other means known in the art.

[0066] In block 704, a certain number of particles may be injected at or within the feature region created in block 702. The particles may be injected by one or more particle injectors (e.g., Figure 1A The number of particles may be injected by a particle injector 106 in the plasma confinement device. These particles may include fusion fuel particles (e.g., deuterium, tritium), impurity particles (e.g., neon, other rare gases, carbon, silicon, etc.), or a combination of fuel particles and impurity particles. The number of particles may be in the form of particles (e.g., cryogenic particles) and may include more than one particle. In some embodiments, the number of particles may include particles confined in a compact annular body (e.g., a compact magnetic confinement plasma), which may be injected into the confined plasma of the plasma confinement device.

[0067] In some embodiments, injecting this number of particles may create a transport barrier (TB). The TB may be created at the location of the characteristic region. The combination of the increased density gradient due to the injected particles and the magnetic geometry at the characteristic region (e.g., magnetic shear, Shafranov shift, etc.) may sufficiently suppress turbulent transport processes to allow the formation of the TB. The TB may be characterized by large and stable gradients in plasma parameters (including pressure, temperature, and density). The TB may be created at a sub-radial distance (e.g., Figure 1A In other words, the TB may be formed at about 90% of the distance from the center of the confined plasma to the inner wall of the plasma confinement device. In other embodiments, the TB may be formed at different locations suitable for injecting particles to initiate and maintain the TB. For example, the TB may be formed at about 70% of the sub-radial distance or at about 80% of the sub-radial distance.

[0068] As described above, TB can be characterized by a large and stable gradient of plasma pressure. For example, when particles are injected or injected into a characteristic region, the pressure gradient Exceeding the threshold value may indicate the generation of TB. For example, TB may be defined as , where p is the plasma pressure, r is the radial coordinate, and a is the minor radius of the plasma confinement. A factor of 5 may be characteristic of a sufficiently "large" pressure gradient to indicate TB, although other values ​​for this factor are also contemplated. Prior to injecting this number of particles, the pressure gradient may be below a threshold value (e.g., ). After the particles are injected, the pressure gradient can exceed a threshold value (e.g., ), thereby generating TB at or inside the feature area.

[0069] It should be understood that Figure 7 The specific steps shown in provide a specific method for generating a characteristic region of a magnetic field that confines a plasma according to an embodiment of the present invention. Figure 7 The various steps shown in the above-mentioned embodiments may include multiple sub-steps, which may be suitable for various sequential executions of the various steps. In addition, additional steps may be added or removed depending on the specific application. Those of ordinary skill in the art will recognize many variations, modifications, and substitutions.

[0070] Figure 8 is another simplified diagram of an example method 800 for inducing a transport barrier with a first number of particles and maintaining the transport barrier with a second number of particles according to at least one embodiment. Figure 7 Similar to method 700, method 800 may be performed by a plasma confinement system (e.g., Figure 1A The plasma confinement system 100, Figure 4The method may be performed by one or more components of a plasma confinement system 400.

[0071] Method 800 may begin at block 802, where a characteristic region of a magnetic field that confines a plasma is generated. The operations of block 802 may be similar to Figure 7 The operation of box 702.

[0072] At block 804, a first number of particles may be injected into the plasma and deposited at or within a characteristic region of the plasma. The particles may be injected by a particle injector (e.g., Figure 1A The particles may be injected by a particle injector 106 in the confinement region, which may include a particle injector, a neutral beam injector, a small spherical plasma gun or other compact annular plasma injector, or a similar device. The first number of particles may be impurity particles to induce the formation of a transport barrier (TB) at or inside a characteristic region. Since impurity particles (e.g., particles with a high Z number) may more easily induce a TB, the first number of particles injected may include all or part of the impurity particles. The first number of particles may be injected at a first time and for a first duration. The first number of particles may be injected within a first duration (e.g., injecting several particles at one location and injecting particles at different annular locations along the confinement region). Injecting particles within the first duration may limit a time-averaged rate of injection for the first number of particles. In some embodiments, the time-averaged rate of injection may be based on an average value for a time period different from the first duration.

[0073] In block 806, a second number of particles may be injected into the plasma and deposited at or inside the characteristic region of the plasma. Similar to block 804, the second number of particles may be injected by a particle injector. The second number of particles may include fusion fuel particles (e.g., deuterium, tritium). The injection of the second number of particles may occur after the TB is formed (e.g., the TB formed by injecting the first number of particles). The second number of particles may be greater than, less than, or equal to the first number of particles, depending on the desired density to be enhanced at the characteristic region. For example, the first number of particles may be a relatively large number of impurity particles (e.g., large particles) to induce TB, while the second number of particles may be a relatively small number of fusion fuels to maintain TB. The second number of particles may be injected within a second duration, which may define a time average rate of injection for the second number of particles. In some embodiments, the second duration may be greater than the first duration. For example, injecting the second number of fusion fuel particles to maintain TB may take longer than injecting the first number of particles to induce TB. The time average rate of particle injection for the second injection may be significantly less than the time average rate of particle injection for the first injection.

[0074] In some embodiments, both the first number of particles and the second number of particles may include impurity particles, fusion fuel particles, or any suitable combination of particles. For example, the first number of particles may include impurity particles, and the second number of particles may include a mixture of impurity particles and fusion fuel particles. The first number of particles may be the same type of particles as the second number of particles. In some embodiments, the first number of particles may include a first portion of fusion fuel particles (e.g., a portion of the total amount of the first number of particles), and the second number of particles may include a second portion of fusion fuel particles. The second portion may be larger than the first portion.

[0075] In some embodiments, this number of particles may be injected by more than one particle injector.For example, for an annular confinement device, particle injection may occur at multiple locations around the annulus of the device to form TBs along the annular direction of the confined plasma.

[0076] It should be understood that Figure 8 The specific steps shown in provide a specific method for injecting two numbers of particles into a characteristic region of a magnetic field that confines a plasma according to an embodiment of the present invention. According to alternative embodiments, other sequences of steps may also be performed. For example, alternative embodiments of the present invention may perform the steps outlined above in a different order. In addition, Figure 8 The various steps shown in the embodiment may include multiple sub-steps, which may be performed in various orders according to the needs of the various steps. In addition, additional steps may be added or removed depending on the specific application. Those of ordinary skill in the art will recognize many variations, modifications, and substitutions.

[0077] Fig. 9 9 is another simplified diagram of an example method 900 for creating a transport barrier at a characteristic region of a magnetically confined plasma in accordance with at least one embodiment. The method 900 may be performed by a plasma confinement system (e.g., Figure 1A The plasma confinement system 100, Figure 4 The method 900 may be performed by one or more components of a plasma confinement system 400. The plasma confinement system may include a plasma confinement device (e.g., a tokamak), a particle injector (or multiple particle injectors), and a controller, the controller including one or more processors and one or more memories, the one or more memories may store and execute instructions to perform the method 900.

[0078] Method 900 may begin at block 902, where a current in a plasma is adjusted to produce a characteristic region of a magnetic field. The plasma may be confined by a magnetic field within a plasma confinement device. The current may be adjusted by one or more control signals from a controller. The adjustment of the current may produce a current parallel or substantially parallel to the magnetic field at the characteristic region.

[0079] Once the characteristic region is generated, particles may be injected into the plasma of the characteristic region according to block 904. The particle injection into the characteristic region may form a transport barrier at the characteristic region. The operation of block 904 may be similar to that described above for Figure 7 and 8 The operations described by blocks 704 and 804 are described below.

[0080] It should be understood that Fig. 9 The specific steps shown in provide a specific method for generating a transport barrier at a characteristic region of a magnetic field that confines a plasma according to an embodiment of the present invention. Fig. 9 The various steps shown in the embodiment may include multiple sub-steps, which may be performed in various orders according to the needs of the various steps. In addition, additional steps may be added or removed depending on the specific application. Those of ordinary skill in the art will recognize many variations, modifications, and substitutions.

[0081] The computing device can be incorporated as part of the previously described system, such as a system plasma confinement system (e.g., plasma confinement system 100), for generating a characteristic region in a magnetic field and injecting a certain number of particles into the characteristic region. The computing device can be useful for performing aspects of the previously described method. For example, the computing device can be used to control the particle injection rate, injection time, injection duration, for selecting particles (e.g., fusion fuel particles, impurity particles), for controlling the current in the plasma that generates the characteristic region, for receiving signals corresponding to plasma parameter (e.g., temperature, pressure, etc.) measurements, and the like. The example computing device includes hardware elements that can be electrically coupled via a bus (or can communicate in other ways). The hardware elements can include one or more processors, including but not limited to one or more general-purpose processors and / or one or more special-purpose processors (e.g., digital signal processing chips, graphics acceleration processors, video decoders, and / or the like); one or more input devices, which can include but are not limited to a mouse, a touch screen, a keyboard, a remote control, voice input, and / or the like; and one or more output devices, which can include but are not limited to a display device, a printer, a speaker, a servo, a linear actuator, a rotary actuator, and the like.

[0082] The computing device may also include (and / or communicate with) one or more non-transitory storage devices, which may include, but are not limited to, local and / or network accessible storage devices, and / or may include, but are not limited to, disk drives, drive arrays, optical storage devices, solid-state storage devices (such as solid-state drives ("SSDs")), random access memory ("RAM"), and / or read-only memory ("ROM"), which may be programmable, flash-updatable, and / or the like. Such storage devices may be configured to implement any suitable data storage, including, but not limited to, various file systems, database structures, and / or the like.

[0083] The computing device may also include a communication subsystem, which may include, but is not limited to, a modem, a network card (wireless or wired), an infrared communication device, a wireless communication device and / or a chipset (such as a Bluetooth device, a low-power Bluetooth or BLE device, an 802.11 device, an 802.15.4 device, a WiFi device, a WiMax device, a cellular communication device, etc.), a G.hn device, and / or the like. The communication subsystem may allow data to be exchanged with a network, other computer systems, and / or any other device described herein. In many embodiments, the computing device will also include a working memory, which may include a RAM or ROM device, as described above.

[0084] The computing device may also include software elements, such as software elements located in a working memory, including an operating system, device drivers, executable libraries, and / or other code, such as one or more applications, which may include computer programs provided by various embodiments, and / or may be designed to implement methods, and / or configure systems provided by other embodiments, as described herein. Merely as an example, one or more programs described with respect to the above methods may be implemented as codes and / or instructions executable by a computer (and / or a processor within a computer); then, in one aspect, such codes and / or instructions may be used to configure and / or adjust a computer (or other device) to perform one or more operations according to the method.

[0085] A set of these instructions and / or codes can be stored on a non-transient computer-readable storage medium, such as the non-transient storage device described above. In some cases, the storage medium can be incorporated into a computer system, such as the computing device described above. In other embodiments, the storage medium can be separated from the computer system (e.g., removable media, such as optical disks, or cloud or network-based storage systems), and / or provided in the form of an installation package, so that the storage medium can be used to program, configure and / or adjust the computer using the instructions / codes stored thereon. These instructions can be in the form of executable code, which can be executed by a computing device or its components, and / or can be in the form of source and / or installable code, compiled and / or installed on a computing device (e.g., using various commonly available compilers, installers, compression / decompression utilities, etc.), and then in the form of executable code.

[0086] It will be apparent to those skilled in the art that substantial changes may be made according to specific requirements. For example, customized hardware may also be used, and / or specific elements may be implemented in hardware, software (including portable software, such as applets, etc.), or both. In addition, connections to other computing devices (e.g., network input / output devices) may also be employed.

[0087] As described above, in one aspect, some embodiments may employ a computing device to perform methods according to various embodiments. According to one set of embodiments, some or all of the procedures of such methods are performed by a computing device in response to a processor executing one or more sequences of one or more instructions (which may be incorporated into an operating system and / or other code, such as an application) contained in a working memory (e.g., one or more memories). Such instructions may be read into the working memory from another computer-readable medium (e.g., one or more non-transitory storage devices). As an example only, executing a sequence of instructions contained in the working memory may cause the processor to execute one or more procedures of the methods described herein.

[0088] As used herein, the terms "machine-readable medium," "computer-readable storage medium," and "computer-readable medium" refer to any medium that participates in providing data that causes a machine to operate in a particular manner. These media may be non-transitory. In embodiments implemented using a computing device, various computer-readable media may be used to provide instructions / codes to a processor for execution and / or may be used to store and / or carry such instructions / codes. In many specific implementations, computer-readable media are physical and / or tangible storage media. Such media may take the form of non-volatile media or volatile media. Non-volatile media include, for example, optical disks and / or magnetic disks, such as non-transitory storage devices. Volatile media include, but are not limited to, dynamic memory, such as working memory.

[0089] Common forms of physical and / or tangible computer readable media include, for example, floppy disks, foldable disks, hard disks, magnetic tapes or any other magnetic media, CD-ROMs, any other optical media, any other physical media with marking patterns, RAM, PROMs, EPROMs, FLASH-EPROMs, any other memory chips or cassettes, or any other medium from which a computer can read instructions and / or code. Network-based and cloud-based storage systems may also be useful forms of computer readable media.

[0090] Various forms of computer-readable media may be used to transmit one or more sequences of one or more instructions to a processor for execution. By way of example only, the instructions may initially be carried on a magnetic disk and / or optical disk of a remote computer. The remote computer may load the instructions into its dynamic memory and send the instructions as a signal over a transmission medium for receipt and / or execution by a computing device.

[0091] The communication subsystem (and / or its components) typically receives the signal, and the bus can then transfer the signal (and / or the data, instructions, etc. carried by the signal) to the working memory, from which the processor retrieves and executes the instructions. The instructions received by the working memory may optionally be stored on a non-transitory storage device before or after execution by the processor.

[0092] It should also be understood that the components of the computing device can be distributed. For example, certain processing can be performed using a first processor in one location, while other processing can be performed by another processor away from the first processor. Optionally, the system described herein can include multiple independent processors that can exchange instructions or issue commands or provide data to each other. Other components of the computing device can be distributed similarly. Therefore, the computing device can be interpreted as a distributed computing system that performs processing at multiple locations. In some cases, depending on the context, the computing device can be interpreted as a single computing device, such as different laptops, desktop computers, etc.

[0093] Although examples and features of the disclosed principles are described herein, modifications, adjustments, and other implementations may be made without departing from the spirit and scope of the disclosed embodiments. In addition, the words "comprise," "have," "contain," and "include," and other similar forms are intended to be equivalent in meaning and open-ended, i.e., one or more items following any of these words are not meant to be an exhaustive list of the one or more items, or to be limited to the listed one or more items. It must also be noted that, as used herein, the singular forms "a," "an," and "the / said" include multiple referents unless the context clearly dictates otherwise.

[0094] It should also be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes thereof will be suggested to those skilled in the art and are to be included within the spirit and metes and bounds of the present application and the scope of the appended claims.

Claims

1. A method comprising: A characteristic region in a plasma confinement device that produces a magnetic field that confines the plasma; as well as A number of particles are injected into the plasma at or within the feature region, thereby creating a transport barrier at or within the feature region.

2. The method of claim 1, wherein the characteristic region is defined by a region of negative magnetic shear in the magnetic field confining the plasma.

3. The method of claim 1, wherein the characteristic region is defined by a region of low magnetic shear in the magnetic field confining the plasma.

4. The method of claim 1, wherein the characteristic region is defined by a large Shafranov shift.

5. The method of claim 1, wherein the characteristic region is defined by a specific shape of a magnetic surface of the magnetic field that confines the plasma.

6. The method of claim 1, wherein the characteristic region is defined by a resonant magnetic perturbation of the magnetic field that confines the plasma.

7. The method of claim 1, wherein the characteristic region is defined by a combination of magnetic shear, Shafranov shift, the shape of a magnetic surface that confines the magnetic field of the plasma, and resonant magnetic perturbations of the magnetic field.

8. The method of claim 1, wherein creating the characteristic region comprises creating a current in the plasma, the current being parallel to the magnetic field at the characteristic region.

9. The method of claim 1, wherein the transport barrier is characterized by a pressure gradient dp / dr of the plasma exceeding a threshold value.

10. The method of claim 9, wherein the threshold is 5 x p / a, where p is the plasma pressure, and where a is the minor radius of the plasma confinement device.

11. The method of claim 1, wherein the transport barrier is created at a location approximately 70% of a minor radius of the plasma confinement device.

12. The method of claim 1, wherein the transport barrier is created at a location approximately 80% of a minor radius of the plasma confinement device.

13. The method of claim 1, wherein the transport barrier is created at a location approximately 90% of a minor radius of the plasma confinement device.

14. The method of claim 1, wherein the number of particles comprises fusion fuel particles.

15. The method of claim 14, wherein the fusion fuel particles comprise deuterium or tritium.

16. The method of claim 1, wherein the number of particles comprises contaminant particles. 17 . The method according to claim 16 , wherein the impurity particles include at least one of the following substances: carbon, silicon, a rare gas, or an element with an atomic number Z less than 21.

18. A method comprising: A characteristic region that produces a magnetic field that confines the plasma; injecting a first number of particles into the plasma at or within the characteristic region at a first time and for a first duration, thereby creating a transport barrier at or within the characteristic region; as well as A second number of particles are injected into the plasma at or within the characteristic region at a second time and for a second duration.

19. The method of claim 18, wherein the characteristic region is defined by a region of negative magnetic shear in the magnetic field confining the plasma.

20. The method of claim 18, wherein the characteristic region is defined by a region of reduced magnetic shear in the magnetic field confining the plasma.

21. The method of claim 18, wherein the characteristic region is defined by a large Shafranov shift.

22. The method of claim 18, wherein the characteristic region is defined by a particular shape of a magnetic surface of the magnetic field that confines the plasma.

23. The method of claim 18, wherein the characteristic region is defined by a resonant magnetic perturbation of the magnetic field that confines the plasma.

24. The method of claim 18, wherein the characteristic region is defined by a combination of magnetic shear, Shafranov shift, shape of a magnetic surface confining the magnetic field of the plasma, and resonant magnetic perturbations of the magnetic field.

25. The method of claim 18, wherein the first number of particles includes at least a portion of contaminant particles.

26. The method of claim 25, wherein the second number of particles comprises foreign particles.

27. The method of claim 25, wherein the second quantity of particles comprises fusion fuel particles.

28. The method of claim 25, wherein the second quantity of particles comprises a mixture of impurity particles and fusion fuel particles.

29. The method of claim 25, wherein a time-averaged rate of particle implantation for the second number of particles is less than a time-averaged rate of implantation for the first number of particles.

30. The method of claim 18, wherein the first number of particles comprises a first portion of fusion fuel particles and the second number of particles comprises a second portion of fusion fuel particles, and wherein the second portion is greater than the first portion.

31. The method of claim 18, wherein the second duration is greater than the first duration.

32. A system comprising: Plasma confinement device; Particle injector; and A controller comprising: one or more processors; and one or more memories storing computer-executable instructions that, when executed by the one or more processors, cause the system to at least: adjusting the current of the plasma confined by the magnetic field in the plasma confinement device to produce a characteristic region of the magnetic field; and A certain number of particles are injected into the plasma at or within the feature region using the particle injector, thereby forming a transport barrier at or within the feature region.

33. The system of claim 32, wherein the plasma confinement device is one of a tokamak, a stellarator, or a torus pinch device.

34. The system of claim 32, wherein the particle injector is configured to inject the number of particles at a high velocity particle rate.

35. The system of claim 33, wherein the number of particles comprises a portion of cryogenically frozen particles.

36. The system of claim 32, wherein the particle injector is configured to inject the number of particles in a magnetically confined plasma.

37. The system of claim 36, wherein the magnetically confined plasma comprises a compact toroid.

38. The system of claim 32, wherein the number of particles is a first number of particles, wherein the first number of particles is injected at a first time and for a first duration, and wherein the one or more memories store additional computer executable instructions that, when executed with the one or more processors, cause the system to further use the particle injector to inject a second number of particles at a second time and for a second duration, the second number of particles maintaining the transport barrier for the second duration.

39. The system of claim 38, wherein the first number of particles comprises impurity particles and the second number of particles comprises fusion fuel particles.

40. The system of claim 38, wherein the first number of particles comprises impurity particles and the second number of particles comprises a mixture of fusion fuel particles and impurity particles.

41. The system of claim 38, wherein the first number of particles comprises a first portion of fusion fuel particles and the second number of particles comprises a second portion of fusion fuel particles, and wherein the second portion is greater than the first portion.

42. The system of claim 38, wherein a time-averaged rate of implantation of the second number of particles is less than a time-averaged rate of implantation of the first number of particles.

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