Material conveying system

Abstract

The present invention provides a material delivery system for a plasma system, the delivery system comprising: a receiver assembly comprising a plurality of receivers and apertures through which material is delivered to the plasma system; and a material feeder assembly for providing material to the receiver assembly wherein the receiver assembly is operable to move between a material transport configuration in which the aperture is aligned with the material feeder assembly to allow material to pass through the receiver assembly and a plurality of material collection configurations in which the aperture is aligned with the material feeder assembly to allow material to pass through the receiver assembly. In the plurality of material collection configurations, a respective one of the receivers obstructs material from passing through the receiver assembly to allow material to be collected by the receiver.

Description

[0001] This invention was made jointly by Tokamak Energy Limited, UT-Battelle, LLC, the management and operating contractor for the U.S. Department of Energy's Oak Ridge National Laboratory, and The Trustees of Princeton University, the management and operating contractor for the U.S. Department of Energy's Princeton Plasma Physics Laboratory, under CRADA No. NFE-19-07769. The U.S. Government has certain rights in this invention. Technical Field

[0002] The present invention relates to a material delivery system for a plasma system and an operating method thereof. Background Art

[0003] Impurity implantation is the process of introducing so-called "impurities"—in the form of powders (e.g., particles <250 μm) or granules (e.g., particles >250 μm to several millimeters)—into the plasma vessel of a magnetically confined plasma system before and / or during plasma operation. Example impurities include lithium, boron, boron nitride, and carbon. Impurity implantation advantageously allows for real-time conditioning of the plasma and plasma vessel walls. For example, impurity implantation has been shown to effectively mitigate damage to plasma vessel walls during disruption events and facilitate high-confinement plasma operation. Furthermore, as plasma systems move toward longer pulse durations, real-time control of plasma vessel wall conditioning via impurity implantation during the pulse will be necessary, as traditional methods (e.g., glow discharge cleaning) cannot be used in plasma systems with permanently active magnetic fields.

[0004] Figure 1A and 1B A known powder drop system 100 for a magnetically confined plasma system is shown. The powder drop system includes: a primary powder reservoir 102; a secondary powder reservoir 104; a horizontal trough 106 for receiving powder from reservoirs 102 and 104; a drop tube 108 through which powder can pass into a plasma vessel (not shown); two piezoelectric actuators 110 operable to oscillate the trough 106 and secondary reservoir 104, thereby driving powder from the trough into the drop tube 108; and a powder diverter 112 comprising a side tube 112a extending from the drop tube, an arm 112b, and a receiver 112c. FIG1A shows the powder drop system in an open configuration, wherein the diverter arm 112b does not obstruct the passage 114 of powder through the drop tube into the plasma vessel. Figure 1BThe powder drop system 100 is shown in a closed configuration, wherein the diverter arm 112b has been moved into the drop tube, directing a channel 116 of powder to a receptacle for waste disposal.

[0005] Figure 1A and 1B The powder drop system 100 shown has a single set of powder reservoirs 102, 104 and is configured to drop only a single type of powder source. However, other known systems are capable of dropping up to four different types of powder in total by adding additional powder reservoirs 102, 104, troughs 106, and piezoelectric actuators 110 for each additional powder type.

[0006] However, plasmas are highly sensitive to these injected impurities. For example, Bodner et al., in their article "Initial results from boron powder injection experiments in WEST lower single null L-mode plasmas," published in HAL Open Science on June 15, 2022, report that boron powder mass injection rates greater than approximately 17 mg / s can lead to plasma disruption (i.e., instability). Therefore, proper calibration and commissioning of the powder drop system is crucial.

[0007] Calibrating each set of piezoelectric actuators 110 in powder drop system 100 involves determining the relationship between the mass flow rate of the powder drop and the sinusoidal voltage profile that excites the set of actuators. For example, the mass flow rate can be determined using an optical flow meter, which is known to those skilled in the art. One method for calibrating a powder drop system is described, for example, in Section 5 of "A Multi-Species PowderDropper for Magnetic Fusion Applications" by Nagy et al., published on May 16, 2018.

[0008] It is of course important that powder does not enter the plasma vessel during calibration and / or commissioning of the powder drop system 100. For this reason, the prior art system shown in Figures 1A and 1B includes a powder diverter 112 for diverting the powder flow from the drop tube 108 into a receiver 112c.

[0009] One problem with existing systems is that different types of powder (e.g., particle size, material) end up mixed together in receiver 112c. These mixed powder types cannot be easily separated and are often discarded, which is both wasteful and expensive. For example, mixed powders containing lithium require careful handling and disposal because lithium powder reacts with ambient moisture.

[0010] There is a need for an improved powder drop system for a magnetically confined plasma system. Summary of the Invention

[0011] According to a first aspect of the present invention, a material delivery system for a plasma system is provided. The material delivery system includes a receiver assembly having a plurality of receptacles and an orifice through which material is delivered to the plasma system, and a material feeder assembly for providing material to the receiver assembly. The receiver assembly is operable to move between a material delivery configuration, in which the orifice is aligned with the material feeder assembly to allow material to pass through the receiver assembly, and a plurality of material collection configurations, in which a respective one of the receptacles blocks material from passing through the receiver assembly to allow material to be collected by the receptacle. This system advantageously allows different forms of material (e.g., different powder size ranges, shapes, etc.) to be collected in different receptacles, thereby preventing the mixing of different material forms. This system also advantageously allows for the collection of larger quantities of material compared to a system having only a single receptacle.

[0012] Optionally, the material feeder assembly includes a material selection mechanism for selectively providing one or more of a plurality of different materials to the receiver assembly. The materials may differ in physical and / or chemical properties. For example, the different materials may have the same or substantially the same chemical composition, but may have particles of different sizes or shapes, or may have different physical states (e.g., in some cases, the material(s) may be provided in liquid form). Alternatively, or in addition, the different materials may have different chemical compositions; for example, the different materials may be powdered or granular lithium, boron, and carbon, respectively. Such a system can then collect the different materials in separate receivers, thereby at least partially avoiding the mixing of the different materials. Separate collection of the different materials can significantly reduce costs. In one specific example, a first receiver is used to collect lithium, a second receiver is used to collect carbon, and a third receiver is used to collect boron. In this specific example, the steps required to extract lithium from the mixed powders can be avoided without losing lithium.

[0013] Preferably, although not necessarily, the number of receptacles in the receptacle assembly is equal to or greater than the number of different material types that the material feeder assembly is capable of (e.g., configured to) provide. For example, there may be a one-to-one correspondence between different materials that can be provided and receptacles. This ensures that there is at least one receptacle for each different material, thereby preventing mixing of different materials.

[0014] The material conveying system may further include a controller configured to control the configuration of the receiver assembly based on determining that the material feeder assembly next requires calibration and / or commissioning of the material. For example, if the material feeder assembly next requires calibration for material "A," the controller is configured to modify the configuration of the receiver assembly to the corresponding configuration "A." If the material feeder assembly subsequently requires calibration for material "B," the controller is configured to modify the configuration of the receiver to the corresponding configuration "B." In this manner, the system provides the desired functionality for collecting different materials "A" and "B" in separate receivers, thereby avoiding mixing. As described above, material "A" and material "B" may differ in physical and / or chemical properties.

[0015] In some embodiments, the receiver assembly can be operable to simultaneously move the aperture and the receiver. For example, the aperture can be disposed in a mount that supports the receiver (e.g., a plate having a plurality of apertures with receivers disposed therein, wherein at least one aperture does not have a receiver). The receiver assembly can then be operable to move the mount (e.g., rotate the plate) to achieve each of the material delivery and material collection configurations.

[0016] Optionally, the plurality of receivers and the aperture are arranged or disposed co-linearly with respect to each other.

[0017] Alternatively, the plurality of receivers and the apertures are arranged or disposed circumferentially relative to each other (i.e., spaced apart from each other around the periphery of a circle or polygon). This arrangement can be more compact than a linear arrangement, saving space in the material conveying system (at least in one direction).

[0018] The material conveying system may include one or more linear actuators operable to move each receiver along a linear path, for example, between a first position in which the corresponding receiver is positioned to collect material entering the receiver assembly and a second position in which the corresponding receiver allows material to pass through the receiver assembly.

[0019] The material conveying system may alternatively include one or more rotary actuators operable to move each receiver along a curved path, for example, between a first position in which the corresponding receiver is positioned to collect material entering the receiver assembly and a second position in which the corresponding receiver allows material to pass through the receiver assembly.

[0020] The or each linear actuator or the or each rotary actuator may be pneumatic or hydraulic, i.e., configured to operate pneumatically or hydraulically. Pneumatics and hydraulics are not affected by the high magnetic fields present in some plasma systems. In contrast, the proper operation of other types of actuators (e.g., electromagnetic actuators) may be adversely affected by these fields. Therefore, pneumatically or hydraulically operated actuators advantageously provide improved control of the system.

[0021] Optionally, the material delivery system includes a conduit assembly having a first conduit extending from the material feeder assembly to the receiver assembly; and a second conduit extending from the receiver assembly, through which material can pass. An end portion of the second conduit distal from the material feeder assembly can be configured to couple to a vessel wall of the plasma system. The conduit assembly can facilitate coupling between the material delivery system and the plasma system, thereby enabling material to be delivered from the material feeder assembly to the plasma system.

[0022] The material feeder assembly can be arranged relative to the receiver assembly such that, during use, material provided by the feeder assembly enters the receiver assembly by gravity. Advantageously, no mechanism for pushing the material (against gravity) is required, saving energy costs and simplifying the system design. In this case, the material feeder assembly can be a conventional drip system, such as shown in FIG1 .

[0023] The material may include any one or more of the following in powdered or granular form: lithium, boron, boron nitride, and carbon. Other elements with low atomic numbers (e.g., Z < 20) may also be used in powdered or granular form. The powder may comprise particles having an average diameter (or other characteristic maximum dimension) of less than 250 μm. The average diameter (or other characteristic maximum dimension) of the particles may range from 250 μm to 5 mm. Each group of powdered or granular lithium, boron, or carbon may include powders / particles having different physical properties. For example, powders / particles of varying sizes, size distributions (i.e., mean size and standard deviation), and / or shapes (e.g., spherical, cubic, etc.).

[0024] The material delivery system may further include a material flow meter for calibrating the material feeder assembly. The material flow meter is positioned relative to the material feeder assembly and the receiver assembly so as to measure the flow rate (eg, mass flow rate) of the material provided to the receiver assembly.

[0025] In a specific example, the material flow meter includes: (i) a calibrated LED or other light-emitting device configured to emit a collimated light beam along a path across a material flow entering a receiver assembly; and (ii) a detector arranged to measure the light intensity of the collimated light beam reaching the detector. As material is supplied to the receiver assembly, particles of the supplied material obstruct the collimated light beam, and the measured light intensity decreases. By monitoring this change in light intensity, the flow rate (e.g., mass flow rate) and the total mass of the material supplied to the receiver assembly can be calculated in a known manner.

[0026] During calibration, one of the plurality of receptacles can be positioned to collect material entering the receptacle assembly so that the material does not reach the plasma system. This avoids injecting an uncontrolled (eg, excessive) or inaccurate amount of material into the plasma system.

[0027] The calibration process itself involves measuring the material flow rate using a material flow meter and adjusting the control parameters for the material feeder assembly based on the measured flow rate. For example, this can be done by adjusting the amplitude and / or frequency of the sinusoidal potential of the piezoelectric actuator 110 until the desired material flow rate (e.g., 10 mg / s) is achieved. These control parameters can then be used to precisely deliver the desired amount of material. For example, by operating the material feeder assembly for a period of 1 second using these determined control parameters, the material feeder assembly can deliver 10 mg.

[0028] According to a second aspect of the present invention, a plasma system is provided, comprising the material delivery system as described above in conjunction with the first aspect.

[0029] According to a third aspect of the present invention, a method for operating a material delivery system installed in a plasma system is provided. The material delivery system comprises: a plurality of receivers; and a material feeder assembly for providing material to the plasma system. The material delivery system may also be as described in conjunction with the first aspect. The method comprises: selecting a first receiver from the plurality of receivers, and moving the first receiver to a position that allows material provided by the material feeder assembly to be collected in the first receiver. Advantageously, operation of the material delivery system allows material to be collected in different receivers.

[0030] The method may further include selecting a first material from a plurality of different materials to be provided to the plasma system by the material feeder assembly, and collecting the first material in the first receptacle. Advantageously, the material delivery system operates to selectively collect different materials in different receptacles. For example, receptacle "A" may be used to collect material "A," receptacle "B" may be used to collect material "B," receptacle "C" may be used to collect a mixture of materials "C," and so on.

[0031] Optionally, the method is performed during calibration and / or commissioning of the material feeder assembly for the first material and / or other materials that the material feeder assembly can provide. The calibration process has been described above in conjunction with the first aspect and will not be repeated in full here. The calibration process is described as comprising: (i) measuring the material flow rate when the receiver is in the position; and (ii) adjusting control parameters for the material feeder assembly based on the measured material flow rate. Commissioning of the material feeder assembly is performed in substantially the same manner.

[0032] The calibration process can be repeated for one or more additional materials. For example, after completing calibration and / or commissioning for a first material, a second receptacle from the plurality of receptacles can be selected and moved to a position where it can collect a second material from the material feeder assembly. The first receptacle is moved away from the material collection position of the first receptacle to make room for the second receptacle. The material feeder assembly can then be selected to provide a second material from a plurality of different materials to the plasma system and collect the second material in the second receptacle.

[0033] Optionally, the material delivery system further comprises an orifice, and after completing calibration and / or debugging of the first material and / or the second material, the method further comprises: moving the orifice to a position allowing the material provided by the material feeder assembly to pass through and enter the plasma chamber of the plasma system; and operating the material feeder assembly to inject the first material and / or the second material into the plasma chamber.

[0034] In some cases, the receiver assembly can be provided (e.g., sold) separately from the material feeder assembly. For example, a receiver assembly for use in a material delivery system of a plasma system can be provided, the receiver assembly comprising a plurality of receivers and an orifice through which material can pass. The receiver assembly is operable to move between a material delivery configuration, in which the orifice is arranged to allow material to pass through the receiver assembly, and a plurality of material collection configurations, in which a respective one of the receivers blocks material from passing through the receiver assembly to allow the material to be collected by the receiver. Further details of the receiver assembly are described above in conjunction with the first aspect and, for the sake of brevity, are not repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG1 is a known powder dropping system;

[0036] 2A and 2B are cross-sectional views of exemplary receiver assemblies;

[0037] Figure 3 is a schematic diagram of a plan view of a receiver assembly;

[0038] Figure 4 is a method flow chart; and

[0039] Figure 5 is a cross-sectional view of an exemplary receiver. DETAILED DESCRIPTION

[0040] The present disclosure provides a material delivery system for a plasma system. In use, the delivery system delivers material into a plasma of the plasma system or into a plasma confined by the plasma system. The delivery system includes a receiver assembly having a plurality of receivers and an orifice through which material is delivered to the plasma system; and a material feeder assembly for providing material to the receiver assembly.

[0041] The material feeder assembly can be capable of providing one or more of a plurality of different materials to the plasma system. Materials can be categorized into different classes based on their physical properties and / or their chemical properties. Two materials are classified into different classes (i.e., are different) if they differ (significantly) in any of these properties. For example, two materials with the same chemical composition can be different if they have different physical forms. For example, if one of the materials is a liquid and the other is a solid, if the materials are allotropes (e.g., different carbon allotropes), or if the materials have particles of different sizes, shapes, etc.

[0042] Example materials include elemental (i.e., >99% purity) powders or granules of lithium, boron, boron nitride, or carbon, or their alloys. Other example materials include other powders or granules of low atomic number elements (e.g., Z < 20) and their alloys.

[0043] The proposed receiver assembly is capable of moving between various configurations. For example, from a material delivery configuration, in which the aperture aligns with the material feeder assembly to allow material to pass through the receiver assembly, to a material collection configuration in which a different receiver blocks material from passing through the receiver assembly. Because each receiver is capable of receiving material when positioned to block material from passing through, the proposed material delivery system is capable of using different receivers to collect different materials. Thus, the proposed material delivery system advantageously alleviates at least the problem of intermixing of different materials.

[0044] Figure 2A and Figure 2B A cross-sectional view of a material delivery system 200 is shown. The material delivery system 200 includes a receiver assembly 202 and a material feeder assembly (not shown). An exemplary material feeder assembly that can be used with the receiver assembly 202 is the powder drop system 100 from FIG. 1 , which is capable of providing a variety of different materials to the receiver assembly 202. However, other known material feeder assemblies can be substituted for this system, depending on the operational requirements of the plasma system.

[0045] Receiver assembly 202 includes a plurality of receivers 206 and apertures 208 arranged or disposed circumferentially on a mount 210. Receivers 206 are secured to the mount using suitable mechanical fasteners, such as shoulder screws. However, other types of mechanical fasteners may be used. The mount is mechanically coupled to a shaft 214 via a rotary bearing 212. The shaft 214 is in turn mechanically coupled to a rotary actuator assembly 216 for providing rotational power to the mount.

[0046] Rotary actuator assembly 216 includes a stepper motor 216a and a belt drive 216b for amplifying the rotational speed of stepper motor 216a. Rotary stepper motor 216a is operable to move each of receivers 206 along a curved path (e.g., along an arc on mount 210). Shaft 214 is centrally positioned relative to the receivers such that, when stepper motor 216a is activated, mount 210, and therefore receivers 206 and aperture 208, rotate about an axis defined by shaft 214. In the illustrated example, a through-funnel 218 is provided in aperture 208, but this is not required.

[0047] The material delivery system 200 also includes a conduit assembly 204 through which material can be transferred from the material feeder assembly 202 to the plasma system (not shown). Figure 2Adenoted by the arrows in FIG. The conduit assembly includes a first conduit extending from the material feeder assembly to the plasma system and a second conduit extending from the receiver assembly 202 to the plasma system (not shown). Thus, by appropriately positioning the receiver and orifice 208 (and funnel 218), the receiver assembly 202 can selectively allow or prevent material from passing from the material feeder assembly to the plasma system. The end portion of the second conduit closest to the plasma system is provided with a coupling mechanism for attaching or otherwise securing the conduit to the plasma system vessel wall.

[0048] The material delivery system 200 further includes a controller (not shown) for controlling the configuration of the receiver assembly via the rotary actuator assembly 216, such that any particular one of the receivers 206 can be positioned to obstruct material being transferred from the material feeder assembly to the plasma system. The configuration of the receiver assembly can be controlled based on a determination of the material for which the material feeder assembly requires subsequent calibration. Limit switches are used to enable the controller to determine the current configuration of the receiver assembly, although other methods of determining the current configuration of the receiver assembly may also be used.

[0049] For example, if the material feeder assembly is next required to be calibrated for material of type or form "A," the controller modifies the configuration of the receiver assembly to the corresponding configuration "A." In configuration "A," receiver "A" is moved to a position that enables it to collect material provided from the material feeder assembly during the calibration process. If the material feeder assembly is subsequently required to be calibrated for material of type or form "B," the controller modifies the configuration of the receiver assembly to the corresponding configuration "B." In configuration "B," receiver "B" (different from receiver "A") is moved to a position that enables it to collect material provided from the material feeder assembly during the calibration process. When receiver "B" is moved to this position, receiver "A" is moved away from its collection position. After the material feeder assembly is properly calibrated, the controller can modify the configuration of the receiver assembly so that the orifice 208 and the funnel 218 are positioned to allow material to pass through the receiver assembly and enter the plasma system. In this way, the material delivery system has the required functionality to: (i) collect material "A" and material "B" in separate receivers to avoid mixing of the materials, such as during calibration; and (ii) deliver the materials to the plasma system, such as after calibration.

[0050] When used with a plasma system, the interior of receiver assembly 202, including lower portion 202a and upper portion 202b, can be under a partial vacuum, while stepper motor 216a is at a higher pressure, such as ambient pressure. Therefore, to facilitate rotation of mount 210, a bellows-sealed rotary feedthrough 220 is used to connect stepper motor 216a to mount 210. The receiver assembly may also include an electrical feedthrough (not shown) for a limit switch cable (not shown).

[0051] In the example shown, stepper motor 216a is a pneumatic stepper motor. A hydraulic stepper motor is a suitable alternative. Pneumatically or hydraulically operated actuators are unaffected by magnetic fields, whereas electromagnetic actuators can be susceptible to interference issues in magnetic fields greater than 0.03 T (without magnetic shielding). Magnetic field strengths in typical plasma systems far exceed this value. Therefore, pneumatic or hydraulic stepper motors can provide improved control and stability compared to other stepper motors. In a specific example, the pneumatic stepper motor is configured to rotate 3 degrees per valve actuation, and the belt drive 216b amplifies the rotational speed by a factor of 3. More generally, the rotational angle per valve actuation and the speed multiplication factor of the belt drive can be varied for different implementations depending on the desired step size and speed. Optionally, a belt tensioning block (not shown) can be provided to assist the belt drive.

[0052] In the example shown, the rotary bearing 212 is made of ceramic (e.g., ) and has a cage made of PEEK (or any other vacuum compatible polymer known to those skilled in the art). However, other rotary bearings comprising different materials may also be used.

[0053] The material delivery system may also include a material flow meter (not shown) for calibrating the material feeder assembly. The material flow meter is positioned relative to the material feeder assembly and the receiver assembly so that it can measure the flow rate (eg, mass flow rate) of the material provided to the receiver assembly.

[0054] In some embodiments, the material flow meter can be an optical flow meter. In a specific example, the material flow meter includes: (i) a calibrated LED or other light-emitting device configured to emit a (preferably collimated) light beam along a path across the flow of material entering the receiver assembly; and (ii) a detector arranged to measure the light intensity of the light beam reaching the detector. As material is supplied to the receiver assembly, the supplied material obscures the light beam, and the measured light intensity decreases. By monitoring this change in light intensity, the flow rate (e.g., mass flow rate) and the total mass of material supplied to the receiver assembly can be calculated in a known manner.

[0055] Figure 3 Is from Figure 2A and 2B Schematic diagram of a plan view of a receiver assembly 202. As shown, the mounting base 210 of the receiver assembly 202 includes three receivers 306a, 306b, and 306c and an orifice 208 having a funnel 218 therethrough. The particular receiver assembly shown is suitable for use with a material feeder assembly capable of providing two or three different materials, for example, powdered lithium and carbon and / or boron.

[0056] In the specific example shown, a first receiver 306a is configured to receive a first material from the feeder assembly, and a second receiver 306b is configured to receive a second material, different from the first material, from the feeder assembly. A third receiver 306c is configured to receive either or both of the first and second materials from the feeder assembly, for example, when the feeder assembly is operated to simultaneously provide a mixture of the first and second materials. The controller described above then controls the configuration of the receiver assemblies to ensure that the corresponding receivers are moved into position to collect their corresponding material(s) (e.g., during calibration).

[0057] More generally, the number of receptacles in the receptacle assembly may be equal to or greater than the number of different materials that the material feeder assembly is capable of providing (ie, individually providing), as this ensures that a separate receptacle is provided for each different material.

[0058] Now refer to Figure 4 The method flow chart 400 is shown to describe Figure 2A 、 2B and 3 show the operation of the material conveying system.

[0059] In step 402 , a first receiver is selected from a plurality of receivers in a material conveying system, for example, during calibration of the material conveying system.

[0060] In step 404, the first receptacle is moved to a position that allows material provided by the material feeder assembly to be collected in the first receptacle.

[0061] Optionally, in step 406 , a first material is selected from a plurality of different materials that the material feeder assembly is capable of providing to the plasma system.

[0062] Optionally, in step 408 , the first material is collected in a first receiver.

[0063] Optionally, in step 410 (not shown), the first receptacle is moved from its collection position and the orifice of the receptacle assembly is moved to a position that allows material provided by the material feeder assembly to enter the plasma system.

[0064] Figure 4 The method is performed during calibration and / or commissioning of the material feeder assembly. The calibration / commissioning (referred to interchangeably herein) may be performed for any one or a combination of a variety of different materials that the material feeder assembly can provide. For example, specific reference is made to Figure 3 The system described herein may be calibrated to a first material only, a second material only, or a mixture of the first material and the second material in any volume fraction or mass fraction ratio. Those skilled in the art will appreciate that the material to be calibrated for the material feeder assembly depends on the operational requirements of the plasma system (and in particular, its plasma).

[0065] During calibration, one of the plurality of receivers is positioned to collect material entering the receiver assembly to prevent the material from reaching the plasma system. Thus, the introduction of uncontrolled or inaccurate amounts of material into the plasma system can be avoided.

[0066] Calibration involves measuring the material flow rate using a material flow meter while the receiver is in the collection position. Control parameters of the material feeder assembly can be adjusted based on the measured material flow rate. In a specific example, by adjusting the amplitude and / or frequency of the sinusoidal potential of the piezoelectric actuator until a desired material flow rate (e.g., 10 mg / s) is achieved, those control parameters can then be used to precisely deliver the desired amount of material. For example, by operating the material feeder assembly for a period of 1 second using those determined control parameters, the material feeder assembly can deliver 10 mg.

[0067] Steps 402 to 408 can then be repeated for any one or combination of the multiple different materials that the material feeder assembly can provide until calibration for each different material has been completed, or until the material delivery system needs to deliver a corresponding one of those materials to the plasma system. Steps 402 to 408 can also be repeated for the same material if recalibration is required.

[0068] Figure 4 The order in which the method steps are presented is not intended to be limiting. For example, step 406 may be performed before step 402 and / or step 404. When steps 402 to 408 are repeated for different materials and / or receivers, step 410 may be performed while the first receiver is being moved from its collection position.

[0069] Figure 5 shows the Figure 2A 2B and 2C are close-up cross-sectional views of the receiver 206 of the material delivery system 200.

[0070] As shown, receiver 206 defines a cover portion 206a having a tapered inner surface, a base portion 206b, and a sidewall portion 206c extending between cover portion 206a and base portion 206b. The interior volume defined by these portions is suitable for receiving material. In a specific example, the interior volume of receiver 206 is 80 cm³. Larger or smaller volumes for the receiver are also possible.

[0071] exist Figure 5 , a removable pin 222 is shown for removing the receiver 206 from the lower portion 202a of the receiver assembly to the upper portion 202b. Pin 222 includes a latch mechanism 224 at one end, which engages the tapered inner surface of the cover portion 206a for this purpose. A handle is provided at the opposite end to facilitate easy removal of the receiver by an operator. In this particular example, pin 222 is a detent pin, but other mechanisms for removing the receiver are also possible. In this manner, after pressurizing the receiver assembly 202 to ambient pressure, the filled receiver 206 can be removed. To maintain the interior of the assembly 202 clean between replacements of the receiver 206, the assembly 202 can be backfilled with dry nitrogen. Once pressurized, the receiver 206 can be easily removed (e.g., by hand or using a robotic operator), emptied, and replaced in the receiver assembly.

[0072] While the specific material delivery system described above provides powdered lithium, carbon, and / or boron, it is also suitable for providing other and additional materials. For example, powders or granules of other elements (i.e., >99% purity) with low atomic number elements (e.g., Z < 20) and alloys thereof (e.g., boron nitride).

[0073] It will be clear to those skilled in the art that various modifications can be made within the scope of the invention. At least the following variations are possible.

[0074] The receiver assembly may have multiple apertures 208 , thereby reducing the rotation angle required to move the aperture 208 (and optionally, the funnel 218 ) into a position that is in line with the tube assembly 204 .

[0075] The number of receivers may be greater than three, for example there may be four, five, six, seven, eight, nine or ten receivers.

[0076] One or more of these receiver assemblies 202 can be stacked on top of each other so that the material passes through multiple receiver assemblies 202 before entering the plasma system. Then, in addition to the first conduit extending from the material feeder assembly to the plasma system and the second conduit extending from the receiver assembly 202 to the plasma system, the conduit assembly 204 can also include additional conduits extending between adjacent receiver assemblies 202 in the stack.

[0077] The plurality of receivers and orifices can be arranged colinearly relative to one another (rather than circumferentially) and substantially orthogonal to the longitudinal axis defined by the conduit assembly 204. The rotary actuator assembly 216 in FIG. 2 can then be replaced by one or more linear actuators. The one or more linear actuators are capable of moving each receiver along a linear path between a position in which the receiver obstructs passage of material through the receiver assembly and a position in which passage of material through the receiver assembly is unimpeded by the receiver. Such a linear actuator can be provided for each receiver so that each receiver can be linearly actuated independently of the other receivers. Alternatively, the linear actuators can act on the receivers in concert so that the receivers are linearly actuated together, for example, the linear actuators can act on a mounting that supports the receivers.

[0078] Multiple receivers can be arranged along a circumference, with the orifice centrally located relative to those receivers. The rotary actuator assembly 216 in FIG. 2 is then replaced by a plurality of linear actuators, each of which is configured to move a corresponding receiver to and from a circumferential and central position. The central position corresponds to the receiver being co-located with the orifice, such that material entering the receiver assembly is collected by the receiver rather than entering the plasma system through the orifice.

[0079] The linear actuator or actuators may also be pneumatically or hydraulically operated.

[0080] In some examples (e.g., where multiple linear actuators are used), the aperture of the receiver assembly does not move when the receiver assembly 202 changes configuration. Instead, to block material from passing through the receiver assembly, one of the receivers is moved to a position that blocks material from passing through the aperture (i.e., immediately upstream).

[0081] The material feeder assembly of the material delivery system of Figures 2A and 2B can be a drip-type system, wherein the material is provided to the plasma system by the feeder assembly by gravity. Alternatively, the material feeder assembly can include a mechanism for propelling the material into the plasma system, allowing the system to be arranged in any given orientation.

[0082] The material delivery system described above and variations thereof may form part of a plasma system, including a magnetic confinement chamber (or plasma vessel). The plasma system may include, or be part of, any suitable apparatus for confining plasma, such as a tokamak or stellarator.

Claims

1. A material delivery system for a plasma system, the delivery system comprising: a receiver assembly comprising a plurality of receivers and an orifice for delivering material to the plasma system through the orifice; as well as a material feeder assembly, the material feeder assembly being used to provide material to the receiver assembly, wherein the receiver assembly is operable to move between a material delivery configuration in which the aperture is aligned with the material feeder assembly to allow material to pass through the receiver assembly and a plurality of material collection configurations in which a respective one of the receivers obstructs material from passing through the receiver assembly to allow material to be collected by the receiver.

2. The material conveying system according to claim 1, wherein: The material feeder assembly includes a material selection mechanism for selectively providing one or more of a plurality of different materials to the receiver assembly.

3. The material conveying system according to claim 2, wherein: The number of receivers in the receiver assembly is equal to or greater than the number of different material types that the material feeder assembly can provide.

4. The material conveying system according to any one of claims 2 or 3, further comprising a controller configured to control the configuration of the receiver assembly based on determining that the material feeder assembly is the next material that requires calibration and / or debugging.

5. A material conveying system according to any one of the preceding claims, wherein: The plurality of receivers and the aperture are collinearly arranged or disposed relative to one another.

6. The material conveying system according to any one of claims 1 to 4, wherein: The plurality of receivers and the apertures are circumferentially aligned or arranged relative to each other.

7. The material delivery system of claim 5 or 6, further comprising one or more linear actuators operable to move each receiver along a linear path.

8. The material delivery system of claim 6, further comprising one or more rotary actuators operable to move each receiver along a curved path.

9. The material conveying system according to claim 7 or 8, wherein: The or each linear actuator or the or each rotary actuator may be pneumatic or hydraulic.

10. The material delivery system of any preceding claim, further comprising a conduit assembly having a first conduit extending from the material feeder assembly to the receiver assembly and a second conduit extending from the receiver assembly, through which material can pass.

11. The material delivery system according to claim 10, wherein: An end portion of the second conduit distal from the material feeder assembly is configured to be coupled to a vessel wall of a plasma system.

12. A material handling system according to any one of the preceding claims, wherein: The material feeder assembly is arranged relative to the receiver assembly such that material provided by the material feeder assembly enters the receiver assembly by gravity.

13. A material handling system according to any one of the preceding claims, wherein: The material comprises a powdered or granular element with an atomic number lower than 20, in particular any one or more of the following: lithium, boron, boron nitride and carbon.

14. The material delivery system of any preceding claim, further comprising a material flow meter for calibrating the material feeder assembly.

15. A plasma system comprising the material delivery system according to any one of claims 1 to 14.

16. A method of operating a material delivery system installed in a plasma system, the material delivery system comprising: a plurality of receivers, and a material feeder assembly for providing material to the plasma system, the method comprising: selecting a first receiver from the plurality of receivers; and The first receptacle is moved to a position that allows material provided by the material feeder assembly to be collected in the first receptacle.

17. The method according to claim 16, further comprising: selecting a first material from a plurality of different materials to be provided by the material feeder assembly to the plasma system; as well as The first material is collected in the first receiver.

18. The method of claim 17, wherein the method is performed during calibration and / or commissioning of the material feeder assembly for the first material.

19. The method of claim 16 or 17, wherein calibrating the material feeder assembly comprises measuring material flow when the first receiver is in the position.

20. The method of claim 19, further comprising adjusting a control parameter of the material feeder assembly based on the measured material flow rate.

21. The method according to any one of claims 18 to 20, wherein After completing the calibration and / or debugging of the first material, the method further includes: (i) selecting a second receiver from a plurality of receivers; (ii) moving the first receiver away from the material collection position of the first receiver; and (iii) moving the second receiver to a position where second material from the material feeder assembly can be collected.

22. The method according to claim 21, further comprising: operating the material feeder assembly to provide the second material from a plurality of different materials to the plasma system; as well as The second material is collected in the second receiver.

23. The method according to any one of claims 18 to 22, wherein the material delivery system further comprises an orifice, and after completing calibration and / or commissioning of the first material and / or the second material, the method further comprises: moving the orifice to a position allowing material provided by the material feeder assembly to pass through and into a plasma chamber of the plasma system; as well as The material feeder assembly is operated to inject the first material and / or the second material into the plasma chamber.

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