High pressure and deep vacuum electrical feedthrough

Abstract

A detection system is configured for a target material reservoir. The detection system includes: a feedthrough housing associated with a wall of the target material reservoir, the feedthrough housing defining a seal surface; an electrically-conductive member extending through the feedthrough housing; and a compressible element that is electrically insulating. The electrically-conductive member is inside the compressible element. The compressible element contacts the feedthrough housing at the seal surface of the feedthrough housing. The interface between the feedthrough housing seal surface and a surface of the compressible element forms a hermetic seal when the compressible element is compressed.

Description

HIGH PRESSURE AND DEEP VACUUM ELECTRICAL FEEDTHROUGHCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Application No. 63 / 612,447, filed December 20, 2023 which is incorporated herein in its entirety by reference.TECHNICAL FIELD

[0002] The disclosed subject matter relates to an apparatus and method for providing an electrical feedthrough for a target material reservoir in an Extreme Ultraviolet (“EUV”) light system.BACKGROUND

[0003] Extreme ultraviolet (“EUV”) light, for example, electromagnetic radiation having wavelengths of around 50 nanometers (nm) or less (also sometimes referred to as soft x-rays), and including light at a wavelength of about 13 nm, is used in photolithography processes to produce extremely small features in and on substrates, for example, silicon wafers, that are used to produce integrated circuits and various other microelectronic devices.

[0004] Methods for generating EUV light include, but are not limited to, altering the physical state of a source material to a plasma state. The source material includes a compound or an element, for example, xenon, lithium, or tin, with an emission line in the EUV range. In one such method, often termed laser produced plasma (“LPP”), the required plasma is produced by irradiating a source material, for example, in the form of a droplet, stream, or cluster of source material, with an amplified light beam that can be referred to as a drive laser. For this process, the plasma is typically produced in a sealed vessel, for example, a vacuum chamber, and monitored using various types of metrology equipment. The source material, such as xenon, lithium, or tin, which emit in the EUV range when in the plasma state, are commonly referred to as target material since they are targeted and irradiated by the drive laser.SUMMARY

[0005] In some general aspects, a detection system is configured for a target material reservoir. The detection system includes: a feedthrough housing associated with a wall of the target material reservoir, the feedthrough housing defining a seal surface; an electrically-conductive member extending through the feedthrough housing; and a compressible element that is electrically insulating. The electrically- conductive member is inside the compressible element. The compressible element contacts the feedthrough housing at the seal surface of the feedthrough housing. The interface between the feedthrough housing seal surface and a surface of the compressible element forms a hermetic seal when the compressible element is compressed.

[0006] Implementations can include one or more of the following features. For example, the feedthrough housing can define a connecting surface. The detection system can further include a compression device including a connecting surface that mates with the connecting surface of the feedthrough housing. The compression device can compress the compressible element when its connecting surface is engaged with the connecting surface of the feedthrough housing. The detection system can also include an electrical insulator between the compression device and the electrically- conductive member. The connecting surface of the feedthrough housing and the connecting surface of the compression device can be threaded mating surfaces.

[0007] The seal surface of the feedthrough housing can be tapered toward an interior of the target material reservoir and the compressible element can be tapered toward the interior of the target material reservoir when seated in the feedthrough housing.

[0008] The electrically-conductive member can be a rod or a wire having a larger diameter portion facing an interior of the target material reservoir such that a shoulder of the wire abuts an end of the compressible element facing the target material reservoir.

[0009] The seal surface of the feedthrough housing can be a face seal and the compressible element can be a gasket seated between the seal surface and a flange of the wall. The detection system can also include a seal stop positioned between the seal surface and the flange of the wall, the seal stop configured to limit compression of the compressible element. The seal stop can include an insulating material. The compressible element can include polybenzimidazole, polyimide, or polyamide-imide.

[0010] The detection system can further include an electrical insulator between the wall and the electrically-conductive member.

[0011] The electrically-conductive member can include a refractory metal. The electrically-conductive member can include molybdenum, tantalum, rhenium, or tungsten, and the target material in the target material reservoir can include tin. The feedthrough housing can be associated with a removable cap that forms the wall of the target material reservoir. The feedthrough housing can be associated with or mounted at or within a side wall of the target material reservoir. The feedthrough housing can be inside of and demountable from the wall of the target material reservoir. The feedthrough housing can be or form the wall of the target material reservoir.

[0012] The compressible element can be made of a material that: maintains compressibility at temperatures exceeding 200 °C, 250 °C, 300 °C, or within a range of 250 °C - 350 °C, and maintains a hermetic seal at a pressure differential of at least 6,000 kilopascals, at least 10,000 kilopascals, at least 25,000 kilopascals, or within a range of 6,000 kilopascals - 60,000 kilopascals.

[0013] The detection system can further include circuitry electrically connected to the electrically- conductive member and configured to measure a presence of target material in the target material reservoir. The detection system can also include a control system in communication with the circuitry, the control system configured to adjust an amount of target material within the target material reservoir based on the measurement from the circuitry. The control system can be configured to determine oneor more of: whether an amount of target material in the target material reservoir is greater than a maximum threshold and whether an amount of target material in the target material reservoir is less than a minimum threshold.

[0014] The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.DRAWING DESCRIPTION

[0015] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable a person skilled in the relevant art(s) to make and use implementations described herein.

[0016] FIG. 1 is a schematic illustration of an implementation of a target material supply apparatus including a detection system that includes an electrical feedthrough and a feedthrough housing for a reservoir;

[0017] FIG. 2A is a schematic illustration of an implementation of a detection system including an electrical feedthrough and a feedthrough housing for a reservoir;

[0018] FIG. 2B is a close-up view of the schematic illustration of FIG. 2A showing details of the detection system;

[0019] FIG. 2C is a close-up view of a schematic illustration of FIG. 2A showing details of another implementation of the detection system;

[0020] FIGS. 3A-3D are schematic illustrations of different implementations of a detection system including an electrical feedthrough and a feedthrough housing for a reservoir;

[0021] FIG. 4A is a schematic illustration of an implementation of a detection system including an electrical feedthrough and a feedthrough housing for a reservoir;

[0022] FIG. 4B is a close-up view of the schematic illustration of FIG. 4A showing details of the detection system;

[0023] FIG. 5A is a schematic illustration of an implementation of a detection system including an electrical feedthrough and a feedthrough housing for a reservoir;

[0024] FIG. 5B is a close-up view of the schematic illustration of FIG. 5A showing details of the detection system;

[0025] FIG. 5C is a perspective cutaway view of an implementation of a detection system including an electrical feedthrough and a feedthrough housing for a reservoir;

[0026] FIG. 6 is a close-up view of the schematic illustration of FIG. 5B ;

[0027] FIG. 7 A is a schematic illustration of an implementation of a detection system including an electrical feedthrough and a feedthrough housing for a reservoir;

[0028] FIG. 7B is a close-up view of the schematic illustration of FIG. 7 A showing details of the detection system;

[0029] FIG. 8 is a cross-sectional view taken along line 8-8 of the feedthrough housing of FIG. 7B;

[0030] FIG. 9A is a schematic illustration of an implementation of a detection system including an electrical feedthrough and a feedthrough housing for a reservoir; and

[0031] FIG. 9B is a close-up view of the schematic illustration of FIG. 9A showing details of the detection system.

[0032] The features of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and / or structurally similar elements. Additionally, generally, the leftmost digit(s) of a reference number identifies the drawing in which the reference number first appears. Unless otherwise indicated, the drawings provided throughout the disclosure should not be interpreted as to-scale drawings.DESCRIPTION

[0033] Referring to FIG. 1, a detection system 101 includes an electrical feedthrough 164 and a feedthrough housing 160 for a reservoir 113 in target material supply apparatus 100. In some embodiments, the electrical feedthrough 164 is provided to transmit a signal to perform a cleaning process. In some embodiments, the electrical feedthrough 164 is provided to measure an amount of target material 120 in any of the reservoirs that are used to hold target material 120. The target material 120 is a target material that can be in a fluid state (such as a liquid state). In some implementations, the target material 120 can be in a solid state. In the example of FIG. 1, the reservoir 113 is a second reservoir of the apparatus 100 that also includes a first reservoir 112 and a priming tank 114 and the second reservoir 113 is maintained at a high pressure during operation. In other implementations, an electrical feedthrough having the same design as the electrical feedthrough 164 is implemented for other containers within the apparatus 100, such as, for example, the first reservoir 112 or the priming tank 114. The first reservoir 112 and the second reservoir 113 can be configured to hold the target material 120, which can be in a fluid state such as during operation of the target material supply apparatus 120, or in a solid state such as during service operation. The priming tank 114 can hold the target material 120 in either a fluid state or a solid state. A description of the electrical feedthrough 164 in the second reservoir 113 follows and this same description is extended to an electrical feedthrough in other target material containers within the apparatus 100.

[0034] The electrical feedthrough 164 is held securely within the feedthrough housing 160. The electrical feedthrough 164 can allow for high pressure to be maintained in the second reservoir 113. In other implementations, the electrical feedthrough 164 is provided for a reservoir that is held at a low pressure such as at a deep vacuum. The electrical feedthrough 164 includes at least one electrically-conductive member 150 and a compressible element 170, which will be discussed in detail below. For example, the electrically-conductive member 150 can be or can be a part of a conduction-based level sensor that can measure the characteristics, such as the level or temperature of the target material 120 in the second reservoir 113. The compressible element 170 contacts the feedthrough housing 160 at a seal surface (shown and discussed in more detail below). When compressed, the compressible element 170 thereby seals the electrically-conductive member 150 in the feedthrough housing 160 of the second reservoir 113 to allow for a pressure differential to be maintained between an interior of the second reservoir 113 and an exterior of the second reservoir 113 and to prevent material from entering and / or overfilling the second reservoir 113. That is, the interface between the seal surface of the feedthrough housing 160 and a surface of the compressible element 170 forms a hermetic seal when the compressible element 170 is compressed. For example, the compressible element 170 can allow for a high pressure to be maintained within the interior of the second reservoir 113 relative to the exterior of the second reservoir 113.

[0035] In some implementations, the target material 120 is liquid tin, and in this case, the target material 120 is provided to, for example, an output system 124 for use by the output system 124. The level of the tin at various locations (such as the second reservoir 113, the first reservoir 112, or the priming tank 114) within the apparatus 100 can be monitored using the electrical feedthrough 164 without the use of an optical viewport. As such, the electrical feedthrough 164 is not susceptible to issues associated with tin splashing and overfill of tin in the target material container or tin blocking transmission of the electrical signal. Thus, the electrical feedthrough 164 enables measurement and control of the tin in the target material container with an acceptable accuracy.

[0036] The apparatus 100 is configured to supply the target material 120 as a stream of targets 121 (which can be in a fluid state) to the output system 124 by way of a nozzle supply system 140. In order for the output system 124 to function properly or efficiently, a continuous or steady supply of target material is needed. The detection system 101 enables the measurement, monitoring, and maintenance within the second reservoir 113 (or any other fluid container as noted above) to ensure this continuous or steady supply of target material 120 to the output system 124.

[0037] The design of the apparatus 100 is discussed next with reference to FIG. 1. The apparatus 100 includes a first reservoir system 102, a second reservoir system 103, a priming system 104, a target material control system 190, and the nozzle supply system 140. The target material control system 190 is fluidly connected to the priming system 104, the first reservoir system 102, the second reservoir system 103, and the nozzle supply system 140. In some implementations, the target material control system 190 includes a communication apparatus 116 and a controller 106 operable to adjust one or more aspects of the communication apparatus 116. The first reservoir system 102 includes the first reservoir 112 and the second reservoir system 103 includes the second reservoir 113. The priming system 104 includes the priming tank 114, which is a vessel configured to contain the target material 120 (that is produced from solid matter 122). The priming tank 114 is in fluid communication with one or more ofthe first reservoir system 102 and the second reservoir system 103 for at least part of the time during operation of the nozzle supply system 140. The priming system 104 is configured to produce the target material 120 from the solid matter 122. The priming system 104 can fluidly communicate with one or more of the second reservoir system 103 and the first reservoir system 102 to refill the second reservoir system 103 with the target material 120 and to refill the first reservoir system 102 with target material 120, as needed. The priming system 104 can also include a priming chamber 130 configured to receive the solid matter 122 that contains the target material. The priming chamber 130 can include, for example, a removable cover such that the solid matter 122 can be replaced inside the priming chamber 130.

[0038] Because the apparatus 100 includes two reservoir systems 102, 103 in addition to the priming system 104 (which enables refill of the target material into the entire apparatus 100), the target material 120 in the form of a fluid can be transferred between the first and second reservoir system 102, 103 while solid matter 122 of the target material is being added to the priming system 104.

[0039] During operation of the nozzle supply system 140 to supply the stream of targets 121, the target material control system 190 controls the fluid communication between and among the first reservoir system 102, the second reservoir system 103, and the priming system 104 to maintain a continuous supply of the target material 120 to the nozzle supply system 140 so that the stream of targets 121 supplied to the output system 124 is not interrupted.

[0040] The communication apparatus 116 is an adjustable fluid flow path that is able to be in fluid communication with the first reservoir system 102, the second reservoir system 103, the priming system 104, and the nozzle supply system 140. For example, the communication apparatus 116 includes fluid transmission lines 115 and one or more regulation devices 117, 118, 119 configured to regulate, direct, or control the flow of a fluid through the fluid transmission lines 115 by, for example, opening, closing, or partially obstructing various passageways within the fluid transmission lines 115.

[0041] Additionally, the actions that take place within the apparatus 100 do not adversely impact performance of the nozzle supply system 140 that could otherwise arise due to disturbances in fluid pressure. Moreover, in some implementations, the first reservoir system 102 is at a pressure that is the same as a pressure of the nozzle supply system 140 during operation of the nozzle supply system 140, and the first reservoir system 102 can provide a primary source of target material 120 to the nozzle supply system 140.

[0042] Fluid control between and among each of the first reservoir system 102, the second reservoir system 103, the priming system 104, and the nozzle supply system 140 can be independently controlled by the target material control system 190, and in this way, at least one of the reservoir systems 102 or 103, which is in fluid communication with the nozzle supply system 140, can provide a source of target material 120 to the nozzle supply system 140 at all times during operation of the nozzle supply system 140.

[0043] As discussed above, the communication apparatus 116 includes the fluid transmission lines 115 and the one or more regulation devices 117, 118, 119 configured to regulate, direct, or control the flow of a fluid through the fluid transmission lines 115 by, for example, opening, closing, or partially obstructing various passageways within the fluid transmission lines 115. The communication apparatus 116 can include other various fluid control devices not shown that are configured to provide a controllable fluid flow path between the various parts of an apparatus 100. The communication apparatus 116 can include (in addition to the noted fluid transmission lines 115 and one or more regulation devices 117, 118, 119) one or more valves, tubes, fluid flow regulation apparatuses, and tanks.

[0044] Each of the regulation devices 117, 118, 119 can include a valve control apparatus. In this way, fluid flow through a particular regulation device 117, 118, 119 can be adjusted by opening or closing the valve within its valve control apparatus. Each valve control apparatus can include a fluid valve, which can be, for example, hydraulic, pneumatic, manual, solenoid, and / or motor. In some implementations discussed herein, the valve control apparatus within regulation devices 118, 119 includes a freeze valve.

[0045] The first reservoir 112 is maintained at a first pressure Pm, which, in some implementations, is adjustable by an environment control apparatus during operation of the nozzle supply system 140. At some times during operation, the first pressure Pm can be, for example, at from about 6000 kilopascals to about 80,000 kilopascals. During operation of the nozzle supply system 140, the first reservoir 112 is supplying the target material 120 to the nozzle supply system 140.

[0046] The second reservoir system 103 includes the second reservoir 113 that is a vessel configured to contain the target material 120. The second reservoir 113 is in fluid communication with the first reservoir system 102 for at least part of the time during operation of the nozzle supply system 140. The second reservoir 113 is a volume that is defined by a structure that can be formed, lined, or reinforced with molybdenum (Mo), forged Mo, or any material that remains stable and solid above the melting point of the target material 120 and is also not chemically reactive with the target material 120. The second reservoir 113 is in fluid communication with the first reservoir system 102 via the communication apparatus 116 and under control of the controller 106.

[0047] In some implementations, the volume within the structure of the second reservoir 113 is the same size as the volume within the structure of the first reservoir 112; so that the first and second reservoirs 112, 113 can hold / retain the same amount of target material 120. In other implementations, the volume within the structure of the second reservoir 113 can be greater than the volume within the structure of the first reservoir 112. In these implementations, the second reservoir 113 would be able to hold / retain a larger amount of target material 120 than the first reservoir 112. As the second reservoir 113 can hold / retain a larger amount of target material 120, the level of target material 120 in the second reservoir 113 can be critical, and thus the measurement using the electrical feedthrough 164 is desirable.

[0048] The second reservoir 113 is maintained at a second pressure Pm, which can be adjustable by the environment control apparatus during operation of the nozzle supply system 140. The value of the second pressure Pm at any one moment can depend on the current operation of the apparatus 100. For example, at some times, the second pressure Pm of the second reservoir 113 can be the same as a priming pressure Piu at which the priming system 104 is maintained. As another example, at other times, the second pressure P of the second reservoir 113 can be the same as the first pressure Pm at which the first reservoir 112 is maintained. And, still at other times, the second pressure P of the second reservoir 113 can be atmospheric pressure when the second reservoir 113 is in fluid communication with the priming system 104, which is also maintained at atmospheric pressure.

[0049] The electrical feedthrough 164 can utilize the compressible element 170 to maintain the high pressure in the second reservoir 113 while still measuring the level of the target material 120 using the electrically-conductive element 150. As mentioned above, the characteristics of the target material 120 in the second reservoir system 103, and specifically, in the second reservoir 113 of the second reservoir system 103, can be measured by the electrical feedthrough 164. For example, the electrical feedthrough 164 can monitor whether the liquid level of the target material 120 in the second reservoir 113 is high or low, for example, by measuring an electrical signal from the electrically-conductive member 150 of the electrical feedthrough 164 in the second reservoir 113. Another example is to utilize the electrically- conductive member 150 to measure the temperature of the target material 120.

[0050] FIG. 2A illustrates a detection system 201 that includes an electrical feedthrough 264. The detection system 201 can be configured to operate under high pressures for those containers that maintain a pressure differential. Moreover, the detection system 201 is compatible with and non- reactive with target material 220, in some instances. In FIG. 2A, the detection system 201 is configured in a target material reservoir 213, which can correspond to the first reservoir, the second reservoir, or another target material container of an refill apparatus. The target material reservoir 213 is a vessel or a body configured to contain the target material 220 and is in fluid communication with other portions of the refill apparatus.

[0051] As illustrated in FIG. 2A, the detection system 201 includes a feedthrough housing 260, the electrical feedthrough 264, and a compressible element 270. A close-up view 205 is shown in FIG. 2B.

[0052] In this implementation, the feedthrough housing 260 is associated with a wall of the target material reservoir 213. Examples of the placement and design of the feedthrough housing 260 and the design of the target material container (the target material reservoir 213) in which it is mounted are discussed with reference to FIGS. 3A-3D. Referring to FIG. 3A, in some implementations, the feedthrough housing 260 A (in an implementation 201 A of the detection system 201) is a part or portion of a removable cap or lid 213L that forms a top wall of the target material reservoir 213. In other implementations, as shown in FIG. 3B, the feedthrough housing 260B (in an implementation 201B of the detection system 201) is a part or portion of or is associated with a side wall 213W of the target material reservoir 213. In still other implementations, with reference to FIG. 3C, the feedthroughhousing 260C (in an implementation 201C of the detection system 201) is distinct from the removable cap 213L but is mounted within and fixed to the removable cap 213L by way of a sealing system 361C. In these implementations, the feedthrough housing 260C is demountable from the cap 213L by way of the sealing system 361C. In other implementations, as shown in FIG. 3D, the feedthrough housing 260D (in an implementation 20 ID of the detection system 201) is distinct from the side wall 213W of the target material reservoir 213 but mounted within and fixed to the side wall 213W by way of a sealing system 361D. In these implementations, the feedthrough housing 260D is demountable from the side wall 213W by way of the sealing system 361D. An example of the sealing system 361C (or 361D) is discussed below with reference to FIGS. 9 A and 9B.

[0053] The feedthrough housing 260 (or any of 260A-D) can be sized and shaped to fit in the target material reservoir 213. For example, as shown in FIG. 3 A, the feedthrough housing 260 can be the portion of the cap 213L, which is shaped and sized to fit into or onto the target material reservoir 213.

[0054] Referring again to FIGS. 2 A and 2B, the electrical feedthrough 264 is sized and shaped to be inserted into the feedthrough housing 260. The electrical feedthrough 264 is provided to measure the amount of target material 220 in the target material reservoir 213. A portion 205 of FIG. 2 A is shown in more detail in FIG. 2B. As illustrated in FIG. 2B, the electrical feedthrough 264 includes an electrically-conductive member 250 for measuring the amount of target material 220, and the compressible element 270 for maintaining a pressure differential between the external environment and the interior of the reservoir 213 that houses the target material 220. The feedthrough housing 260 defines a seal surface 262 and the compressible element 270 contacts the feedthrough housing 260 at the seal surface 262 such that the interface between the seal surface 262 and the surface of the compressible element 270 forms a hermetic seal when the compressible element 270 is compressed.

[0055] Specifically, the electrically-conductive member 250 can be a part of a conduction-based level sensor that measures the level of the target material 220 in the target material reservoir 213. For example, if the target material 220 is tin in a fluid state, then the electrically-conductive member 250 is a part of a liquid tin sensor for the detection system 201. The electrically-conductive member 250 extends generally along an axial direction 250a.

[0056] The compressible element 270 is made of a material that maintains its compressibility in the environment in which it is placed. For example, the material of the compressible element 270 can be configured to withstand temperatures that exceed 200 °C and maintain a hermetic seal at the pressure differentials noted above. If the target material is tin that is held in a fluid state, then the compressible element 270 is configured to withstand temperatures exceeding the melting point (about 231 °C) of tin. The material of the compressible element 270 is not reactive to the target material 220. For example, the compressible element 270 can be made of a compressible polymer such as polybenzimidazole, polyimide, polyamide-imide, polyetheretheketone, liquid crystal polymers, polyphenylene sulfides, orany suitable combinations thereof. Another example is that the compressible element 270 includes ceramics.

[0057] The feedthrough housing 260 defines the seal surface 262. The seal surface 262 is shaped along an interior surface of the feedthrough housing 260 where the compressible element 270 is in contact and compressed against the feedthrough housing 260. The seal surface 262 can be any conformation or shape based upon the shape of the feedthrough housing 260 and the shape of the compressible element 270. For example, the seal surface 262 can be flat, tapered, curved, conical, stepped, etc. based upon the shape of the surface of the feedthrough housing 260 and the compressible element 270.

[0058] The electrically-conductive member 250 can be a single piece, such as a continuous wire, as shown in FIG. 2B. The electrically-conductive member 250 can be made of a refractory metal that is not reactive to the liquid target material 220 that it can contact. Suitable refractory metals that can be used include, for example, molybdenum, tantalum, rhenium, or tungsten.

[0059] In other implementations, the electrically-conductive member 250 includes a plurality of pieces that are assembled and connected to be electrically conductive, as shown and discussed with reference to FIG. 7B.

[0060] In some implementations, the electrically-conductive member 250 is a wire that is electrically connected to circuitry 245 configured to measure the amount of or presence of target material 220 in the target material reservoir 213. A sensor is thereby formed from the member 250 and the circuitry 245. To this end, the detection system 201 includes a control system 247 in communication with the circuitry 245. In this implementation, the circuitry 245 can be triggered when the level of the target material 220 is above or below a predetermined level. For example, a closed circuit status can be monitored (when the member 250 makes contact with the target material 220 in the target material reservoir 213) and an open circuit can indicate that the member 250 is no longer making contact with the target material 220.

[0061] The control system 247 can be configured to determine one or more of: whether an amount of target material 220 in the target material reservoir 213 is greater than a maximum threshold and whether an amount of target material 220 in the target material reservoir 213 is less than a minimum threshold. Additionally, the control system 247 can be in communication with the target material control system to instruct the target material control system to adjust an amount of target material 220 within the target material reservoir 213 based on the measurement from the sensor (the member 250 and the circuitry 245). Such control can then occur between and among each of the first reservoir system, the second reservoir system, the priming system, and the nozzle supply system by the target material control system.

[0062] In other implementations, the electrically-conductive member 250 is a piezo-electric element configured to provide cleaning to the interior of the target material reservoir 213. In some implementations, the electrically-conductive member 250 is connected to the piezo-electric element. Inother implementations, the electrically-conductive member 250 is a thermocouple or a heat source configured to provide heat to the target material reservoir 213.

[0063] The compressible element 270 is adjacent the electrically-conductive member 250. The compressible element 270 is electrically insulating, which prevents current from flowing between the feedthrough housing 260 and the electrically-conductive member 250. The compressible element 270 is compressible, which means that its volume changes or deforms when pressure is applied to it. The compressible element 270 is shaped to be cooperative with the seal surface 262 of the feedthrough housing 260 such that the compressible element 270 fits within the area defined by the seal surface 262 and the feedthrough housing 260. The compressible element 270 is able to maintain a pressure differential between the target material reservoir 213 and an exterior of the target material reservoir 213. In some implementations, the compressible element 270 is provided in an unfilled state or with strength promoting fillers.

[0064] The compressible element 270 can be rotationally symmetric about the axial direction 250a of the electrically-conductive member 250. In this way, the electrically-conductive member 250 is received in the compressible element 270. The electrically-conductive member 250 can contact the compressible element 270 (as shown in FIG. 2B). Or, there can be a gap or space between the member 250 and the compressible element 270.

[0065] When the electrically-conductive member 250 is located within the interior of the compressible element 270, the electrically-conductive member 250 is electrically insulated from the feedthrough housing 260 by the compressible element 270. This electrical insulation is provided by the compressible element 270 being electrically isolating and located between the member 250 and the feedthrough housing 260.

[0066] By providing compression along the axial direction 250a to the compressible element 270 that fits within the feedthrough housing 260, the interface between the seal surface 262 of the feedthrough housing 260 and a surface of the compressible element 270 forms a hermetic seal when the compressible element 270 is compressed at the seal surface 262.

[0067] The detection system 201 also includes a compression device 272. The compression device 272 is an annular element having an opening through which the electrically-conductive member 250 can pass. The compression device 272 is received in the opening of the feedthrough housing 260 and is adjacent to the compressible element 270. In particular, the compression device 272 defines a connecting surface 273 and the feedthrough housing 260 defines a connecting surface 274, the connecting surface 273 mating with the connecting surface 274 when the compression device 272 is inserted. The compression device 272 compresses the compressible element 270 when the connecting surfaces 273 and 274 are engaged. The connecting surface 273 and the connecting surface 274 can be threaded mating surfaces.

[0068] The detection system 201 can also include an electrical insulator (or isolator) 254 positioned between the compression device 272 and the electrically-conductive member 250. The insulator 254can be made of a plastic, ceramic, or a polymer such as polyimide. In some implementations, the electrically-conductive member 250 can be provided with an insulating coating or sheath that can be provided along the surface of the electrically-conductive member 250 to assist in further electrical insulation between the electrically-conductive member 250 and the feedthrough housing 260.

[0069] Referring to FIG. 2C, the electrically-conductive member 250C includes a shoulder or stop 276 that abuts the end of the compressible element 270 facing the target material reservoir. In this way, the electrically-conductive member 250C is shaped to oppose the force provided by the compression device 272 along the axial direction 250a and also to oppose the force provided by the pressure differential between the interior of the target material reservoir and the exterior.

[0070] Referring to FIGS. 4A and 4B, an implementation 401 of the detection system is described. The target material reservoir 413 is a vessel configured to contain the target material 420 and is in fluid communication with other portions of the refill apparatus. Features discussed above concerning FIGS. 2A and 2B are intended to also apply to FIGS. 4A and 4B where possible.

[0071] As illustrated in FIGS. 4 A and 4B, the detection system 401 includes a feedthrough housing 460, and an electrical feedthrough 464 secured in the feedthrough housing 460.

[0072] A portion 405 of FIG. 4A is shown in more detail in FIG. 4B. As illustrated in FIG. 4B, the electrical feedthrough 464 includes an electrically-conductive member 450 that can be for measuring the amount of target material 420, a compression device 472 to provide compression to seal the electrical feedthrough 464, and a compressible element 470. The compressible element 470 contacts the feedthrough housing 460 at a seal surface 462, and when compressed, the compressible element 470 thereby seals the electrically-conductive member 450 in the feedthrough housing 460 to allow for high pressure to be maintained and to prevent material from entering and / or exiting the second reservoir 413 in which the detection system 401 is placed (FIG. 4A). The interface between the seal surface 462 of the feedthrough housing 460 and a surface of the compressible element 470 forms a hermetic seal when the compressible element 470 is compressed.

[0073] In FIG. 4B, the feedthrough housing 460 defines an opening having a connecting surface 474 and the compression device 472 defines a connecting surface 473. The connecting surfaces 473, 474 mate when the compression device 472 is seated in the opening of the feedthrough housing 460. The compression device 472 is located or seated on one side of the compressible element 470 that faces aware from the target material reservoir. The compression device 472 provides an opposing force along the axial direction 450a to the compressible element 470 from the feedthrough housing 460 as it is inserted through the opening of the feedthrough housing 460. The opening of the feedthrough housing 460 is shaped to cooperate with the compression device 472 and the compressible element 470.

[0074] For example, in the implementation shown in FIG. 4B, the compression device 472 is threaded into the opening defined by the interior connecting surface 474 of the feedthrough housing 460 so that the compression device 472 is inserted into the wall of the feedthrough housing 460 and the threads are mated. The force provided by the compression device 472 along an axial direction 450a compresses thecompressible element 470 to form a seal surface 462 between the compressible element 470 and the electrically conductive member 450.

[0075] The compression device 472 can be any structurally solid material. The compression device 472 can be an electrically-conductive material, such as stainless steel. In the implementation shown in FIG. 4B, the compression device 472 includes a nut 472n that is axially provided on a threaded bolt 472b. The compression device 472 can be formed form a single piece, such as a bolt with a head in the shape of a nut. A gap is defined between the interior of the compression device 472 and the member 450, such gap being large enough to prevent arcing between the compression device 472 and the member 450.

[0076] As also illustrated in FIG. 4B, in this implementation, the compressible element 470 is tapered away from the compression device 472. Thus, the compressible element 470 is wider at the portion facing the compression device 472. This tapered shape facilitates the formation of the hermetic seal at the seal surface 462 when the compression device 472 applies force to the compressible element 470 along the axial direction 450a.

[0077] In the implementation of FIG. 4B, the electrically-conductive member 450 is a wire having a larger diameter portion facing or extending toward an interior of the target material reservoir 413. A shoulder or stop 476 of the member 450 abuts the tapered end of the compressible element 470 facing the target material reservoir 413. In this way, the electrically-conductive member 450 is shaped to oppose the force provided by the compression device 472 along the axial direction 450a and also to oppose the force provided by the pressure differential between the interior of the target material reservoir 413 and the exterior.

[0078] The feedthrough housing 460 is shaped to house and provide stability to the electrically- conductive member 450, the compression device 472, and the compressible element 470 by providing a stop surface 475 for the compressible element 470, and one or more compression device stops 477, 478. By providing these stops 475, 477, 478 in the feedthrough housing 460, the parts of the system 401 can be secured and not slip even under applied pressure.

[0079] The feedthrough housing 460 defines the seal surface 462. The seal surface 462 is shaped along an interior surface of the feedthrough housing 460 where the compressible element 470 is compressed against the feedthrough housing 460. The seal surface 462 can be any conformation or shape based upon the shape of the compressible element 470. In FIG. 4B, the seal surface 462 is a taper based upon the tapered shape of the compressible element 470.

[0080] Similar to FIG. 2A and FIG. 4A, FIGS. 5A-5C illustrate a detection system 501 that includes an electrical feedthrough 564 configured relative to a target material reservoir 513. Features discussed above concerning FIGS. 2A, 2B, 4A, and 4B are intended to also apply to FIGS. 5A-5C where possible. The target material reservoir 513 is a vessel configured to contain target material 520 and is in fluid communication with other portions of the refill apparatus.

[0081] A close-up view 505 (FIG. 5A) is shown in cross section in FIG. 5B and in perspective view in FIG. 5C. In this implementation, the detection system 501 includes a compression device 572 that fits within an opening of a feedthrough housing 560 and a compressible element 570. The compressible element 570 is formed as a gasket or annular ring around an electrically-conductive member 550. The feedthrough housing 560 defines a seal surface 562 and the compressible element 570 contacts the feedthrough housing 560 at the seal surface 562 such that the interface between the seal surface 562 and the surface of the compressible element 570 forms a hermetic seal when the compressible element 570 is compressed.

[0082] The hermetic seal formed at the seal surface 562 can be a face seal, which is a seal that is formed along an annular surface of the feedthrough housing 560. In this case, the compressible element 570 (a gasket) is seated between the seal surface 562 and the electrically-conductive member 550.

[0083] The compression device 572 provides compression along the axial direction 550a to the compressible element 570. The compression device 572 defines a contact surface 573 and the opening of the feedthrough housing 560 defines a contact surface 574. The contact surfaces 573, 574 mate when the compression device 572 is inserted into the opening of the feedthrough housing 560. Similar to FIG. 4B, the contact surface 573 of the compression device 572 can be threaded, flat, or smooth, or any combination of shapes. Moreover, if the contact surface 573 is threaded, then the contact surface 574 includes mating threads. As illustrated, the compression device 572 is an annular-shaped fitting that fits radially around the electrically-conductive member 550 and within the feedthrough housing 560. An electrical insulator 554 can be provided radially between the electrically-conductive member 550 and the compression device 572 if the compression device 572 is made of an electrical conductor. The compression device 572 provides axial compression (along the axial direction 550a) to the compressible element 570 by applying axial pressure via the insulator 554.

[0084] The compression device 572 can be any structural material including electrically-conductive materials, such as stainless steel. For example, the compression device 572 can include a nut 572n that can be axially provided on a threaded bolt 572b such that compression can be provided to the compressible element 570. The compression device 572 can be a single piece, such as a bolt, or can be multiple pieces like a bolt and a nut.

[0085] In FIG. 5B, a ring 580 is located on an outer radial portion of the compressible element 570, between the compressible element 570 and the feedthrough housing 560. The ring 580 acts as an end stop for the compressible element 570 to prevent the compressible element 570 from being pushed or squeezed radially away from the electrically-conductive member 550. The addition of the ring 580 can therefore allow for increasing the seal force with increased pressure along the axial direction 550a. The ring 580 can be a metal, polymer, or ceramic material. For example, the ring 580 can be made of a nickel-cobalt ferrous alloy. The ring 580 can be coated with an insulation material, such as, for example, a polyimide film that can provide electrical insulation.

[0086] In this particular implementation, the electrically-conductive member 550 is electrically insulated from the feedthrough housing 560 by the electrically insulating properties of the compressible element 570, the ring 580, and the insulator 554.

[0087] The insulator 554 is provided to electrically insulate the compression device 572, the feedthrough housing 560, or both from the electrically-conductive member 550. The shape and size of the insulator 554 can vary depending on how much insulation is needed, the size and shape of the electrical feedthrough 554, the compression device 572, the feedthrough housing 560, or the ring 580, or the overall size requirement of the system 501. For example, the insulator 554 can be less than the entire height of the compression device 572, as illustrated in FIG. 5B, or can be extended to be between the electrically-conductive member 550 and the compression device 572. As another example, the insulator 554 can be located between a wall of the feedthrough housing 560 and the electrically- conductive member 550, and can be to the scale as illustrated in FIG. 5B, or can be shaped differently as desired.

[0088] The insulator 554 can be provided as a coating rather than a structural element. For example, the electrically-conductive member 550 can be coated with an electrically insulating coating or barrier to electrically insulate the electrically-conductive member 550 within the feedthrough housing 560.

[0089] FIG. 6 is an alternative implementation of a magnified portion 607 of FIG. 5B. In the implementation of FIG. 6, a ring 680, a compressible element 670, a feedthrough housing 660, an insulator 654, and an electrically-conductive member 650 are illustrated. The feedthrough housing 660 defines a seal surface 662 and the compressible element 670 contacts the feedthrough housing 660 at the seal surface 662 such that the interface between the seal surface 662 and the surface of the compressible element 670 forms a hermetic seal when the compressible element 670 is compressed.

[0090] In this implementation, the feedthrough housing 660, the ring 680, the compressible element 680, and the insulator 654 are cylindrically shaped and surround the electrically-conductive member 650, similar to the implementation illustrated in FIG. 7. By providing these elements as annular elements around the electrically-conductive member 650, the compressible element 680 can be specifically fit to seal the system 501 and allow pressure in the system 501 to be maintained.

[0091] Similar to the ring 580, the ring 680 functions as a radial stop for the compressible element 670. The ring 680 can be a metal, polymer, or ceramic material. For example, the ring 680 can be made of a nickel-cobalt ferrous alloy. The ring 680 can be coated with an insulation material, such as, for example, a polyimide film that can provide electrical insulation. The ring 680 is elongated axially and can therefore provide additional isolation between the electrically-conductive member 650 and the feedthrough housing 660. The ring 680 can be shaped as a monolithic annular ring with a rectangular cross-section, like in FIG. 5B, or it can be shaped as a tapered, contoured ring, as shown in FIG. 6, or it can have a different shape or size than either FIG. 5B or 6.

[0092] The ring 680 assists in the fitting of the compressible element 670 into or onto the electrically- conductive member 650 with the feedthrough housing 660. The ring 680 also provides support for andconstrains the compressible element 670 radially when the compressible element 670 is pressed along the axial direction 550a.

[0093] The compressible element 670 can be polymer, such as a polybenzimidazole (PBI), polyimide (PI), or polyamide-imide (PAI) and can be provided in an unfilled state or with strength promoting fillers. The compressible element 670 is in the form of a gasket that is not electrically conductive, and thus provides electrical isolation between the electrically-conductive member 650 and the feedthrough housing 660.

[0094] Similar to FIGS. 2A, 5A, and 5A, FIG. 7A illustrates a detection system 701 that is in fluid communication with other portions of the system 100 illustrated in FIG. 1. The detection system 701 is configured relative to a target material reservoir 713, which is a vessel configured to contain target material 720 and is in fluid communication with other portions of the refill apparatus. Moreover, FIGS. 7A and 8 show details of the detection system 701. Features discussed above concerning are intended to also apply to FIGS. 7A, 7B, and 8, where possible.

[0095] A portion 705 of FIG. 7A is shown in more detail in FIG. 7B and in cross section in FIG. 8. The detection system 701 includes a feedthrough housing 760 (which is a part of the vessel), an electrically-conductive member 750, which includes a rod or a wire 751 and a fitting 752, a compression device 772, a compressible element 770, a ring 780, a thermal expansion compensation washer 758, an insulator 754, and an anti-rotation washer 756. Descriptions of other implementations are intended to apply to this implementation as well. The feedthrough housing 760 defines a seal surface 762 and the compressible element 770 contacts the feedthrough housing 760 at the seal surface 762 such that the interface between the seal surface 762 and the surface of the compressible element 770 forms a hermetic seal when the compressible element 770 is compressed.

[0096] The feedthrough housing 760 is a removable gas cap that has cut-out areas to fit and contain the electrically-conductive member 750, the wire 751, the fitting 752, the compression device 772, the compressible element 770, the ring 780, the thermal expansion compensation washer 758, the insulation cup 754, and the anti-rotation washer 756 as a single, compound piece of the detection system 701.

[0097] As illustrated on the left side of the anti-rotation washer 756, the feedthrough housing 760 can be shaped to allow the anti-rotation washer 756 to be inserted into a wall of the feedthrough housing 760 such that the anti-rotation washer 756 is locked into place to prevent rotation of the anti-rotation washer 756 about the axial direction 750a. The feedthrough housing 760 can be shaped to allow the compression device 772 to extend into the feedthrough housing 760 to allow the compression device 772 to provide compression to the elements between the compression device 772 and the feedthrough housing 760. In particular, the compression device 772 defines a contact surface 773 and the interior opening of the feedthrough housing 760 defines a contact surface 774. The contact surfaces 773, 774 mate when the compression device 772 is inserted into the opening of the feedthrough housing 760.

[0098] The feedthrough housing 760 can be shaped to allow an outer portion of the ring 780 to be shaped at an angle to fit and allow the compression from the feedthrough housing 760 to the compressible element 770.

[0099] The electrically-conductive member 550 from FIG. 5B is replaced in this implementation illustrated in FIG. 7B by the member 750, which includes two or more pieces, such as the wire 751 and the fitting 752. Different electrically-conductive materials can be used for the wire 751 and the fitting 752. For example, in general, the electrically-conductive member 750 can have portions that are made of refractory metals (such as those noted above), and portions that are electrically conductive, but not made of a refractory metal. A suitable non-refractory metal can include stainless steel.

[0100] For example, the refractory metal portions can be provided where exposure to the target material 720 is more prevalent. The electrically-conductive member 750 can have refractory metal in the portions where the target material 720 is present, such as within the target material reservoir 713 and external to the feedthrough housing 760 or within the target material 720. The electrically conductive, non-refractory metal portions of the electrically-conductive member 750 can be present within the feedthrough housing 760, within the compressible element 770, or external to the target material reservoir 713. Thus, in this example, the wire 751 can be made of a refractory metal because it is exposed to the target material 720 while the fitting 752 can be made of a non-refractory metal.

[0101] Additionally, by using the wire 751 separate from the fitting 752, electrical conductivity can still be provided, but the shapes or materials can be substituted for efficiency, cost, or conformational purposes.

[0102] Different shapes for the fitting 752 can be provided for structural purposes. For example, the fitting 752 here is used in conjunction with the feedthrough housing 760 to oppose the compression force provided by the compression device 772 along the axial direction 750a to provide compression on the compressible element 770. By providing a wider and thicker fitting 752, the fitting 752 can be more secure within the feedthrough housing 760. Additionally, the material of the fitting752 can be an electrically-conductive material that does not need to be a refractory metal, such as stainless steel (because the fitting 752 does not come in contact with the target material 720), while the wire 751 can still be a refractory metal (because the wire 751 comes in contact with the target material 720). By providing the wire 751 that is resistive to the properties of the target material 720, the structural integrity can be maintained while not having to incur the cost to make the fitting 752 of the refractory metal.

[0103] The compression device 772 can have a flat surface, which is depicted, or can have a textured, tapered, threaded, or other surface.

[0104] The compressible element 770 is a gasket that is not electrically conductive, and provides electrical isolation between the electrically-conductive member 750 and the feedthrough housing 760. The compressible element 770 fits between the fitting 752, the ring 780, the wire 751, and the feedthrough housing 760 to provide a seal at the seal surface 762 between the feedthrough housing 760and the compressible element 770 when the compressible element 770 is compressed by the compression device 772.

[0105] In FIG. 7B, the ring 780 is made of non-conductive material such as a ceramic. In this illustration, the ring 780 is tapered to be wider at the portion facing the electrically-conductive body part 752 to allow for a wider contact with the fitting 752 to transfer the force from the compression device 772, and can be a narrower at a portion facing the feedthrough housing 760. This shape allows the ring 780 to provide a stop or constraint along the radial direction adjacent the compressible element 770. In other implementations, the ring 780 is cylindrical or annular (and not tapered).

[0106] The thermal expansion compensation washer 758 is provided to compensate for any thermal expansion in the parts of the system 701. As the system 701 varies in temperature, the elements can expand or contract and the thermal expansion compensation washer 758 can maintain the pressure required to maintain the seal surface 762.

[0107] The insulator 754 in FIG. 7B is an insulation cup provided to electrically insulate the compression device 772, the feedthrough housing 760, or both from the wire 751. Similar to the insulator 454 of FIG. 4B, the shape and size of the insulator 754 can vary depending on how much insulation is needed. For example, the insulator 754 can be less than the entire height of the compression device 772, as illustrated in FIG. 7B, or can be extended to be between the wire 751 and the compression device 772. Also, the insulator 754 can be provided as a coating rather than a structural element. For example, the wire 751 can be coated with an electrically insulating coating or barrier to electrically insulate the wire 751. The insulator 754 is a compressed polyimide, but the material can vary as needed.

[0108] The anti-rotation washer 756 is provided to prevent rotation of and damage to any part of the system 701 by being locked into place in the feedthrough housing 760.

[0109] Referring to FIGS. 9A and 9B, a detection system 901 is shown in which an electrical feedthrough 964 is secured in a feedthrough housing 960 relative to a body 913 that houses target material 920. In this implementation, the feedthrough housing 960 is designed similarly to the feedthrough housing 260C in that it is distinct from a body 913 of the target material reservoir but is mounted within and fixed to the body 913 by way of a sealing system 961. In these implementations, the feedthrough housing 960 is demountable from the body 913 by way of the sealing system 961.

[0110] A portion 905 of FIG. 9 A is shown in more detail in FIG. 9B. As illustrated in FIG. 9B, the electrical feedthrough 964 includes an electrically-conductive member 950 that can be for measuring the amount of target material, a compression device 972 to provide compression to seal the electrical feedthrough 964, and a compressible element 970. The compressible element 970 provides several functions, as discussed above with reference to the compressible element 470. For example, the compressible element 970 contacts the feedthrough housing 960 at a seal surface 962, and when compressed, the compressible element 970 thereby seals the electrically-conductive member 950 in the feedthrough housing 960 to allow for high pressure to be maintained and to prevent material from entering and / or exiting the second reservoir 913 in which the detection system 901 is placed. Theinterface between the seal surface 962 of the feedthrough housing 960 and a surface of the compressible element 970 forms a hermetic seal when the compressible element 970 is compressed.

[0111] In FIG. 9B, the feedthrough housing 960 defines an opening having a connecting surface 974 and the compression device 972 defines a connecting surface 973. The connecting surfaces 973, 974 mate when the compression device 972 is seated in the opening of the feedthrough housing 960. The compression device 972 is located or seated on one side of the compressible element 970 that faces away from the target material reservoir 913 (such as the second reservoir 113). The compression device 972 provides an opposing force along the axial direction 950a to the compressible element 970 from the feedthrough housing 960 as it is inserted through the opening of the feedthrough housing 960. The opening of the feedthrough housing 960 is shaped to cooperate with the compression device 972 and the compressible element 970.

[0112] For example, in the implementation shown in FIG. 9B, the compression device 972 is threaded into the opening defined by the interior connecting surface 974 of the feedthrough housing 960 so that the compression device 972 is inserted into the wall of the feedthrough housing 960 and the threads are mated. The force provided by the compression device 972 along an axial direction 950a compresses the compressible element 970 to form a seal surface 962 between the compressible element 970 and the electrically conductive member 950.

[0113] The compression device 972 can be any structurally solid material. The compression device 972 can be an electrically-conductive material, such as stainless steel. In the implementation shown in FIG. 9B, the compression device 972 includes a nut 972n that is axially provided on a threaded bolt 972b. The compression device 972 can be formed form a single piece, such as a bolt with a head in the shape of a nut.

[0114] As also illustrated in FIG. 9B, in this implementation, the compressible element 970 is tapered away from the compression device 972. Thus, the compressible element 970 is wider at the portion facing the compression device 972. This tapered shape facilitates the formation of the hermetic seal at the seal surface 962 when the compression device 972 applies force to the compressible element 970 along the axial direction 950a.

[0115] The electrically-conductive member 950 is a wire having a larger diameter portion facing or extending toward an interior of the target material reservoir 913. A shoulder or stop 976 of the member 950 abuts the tapered end of the compressible element 970 facing the interior of the target material reservoir 913. In this way, the electrically-conductive member 950 is shaped to oppose the force provided by the compression device 972 along the axial direction 450a and also to oppose the force provided by the pressure differential between the interior of the target material reservoir 913 and the exterior.

[0116] The feedthrough housing 960 is shaped to house and provide stability to the electrically- conductive member 950, the compression device 972, and the compressible element 970 by providing a stop surface 975 for the compressible element 970, and one or more compression device stops 977,978. By providing these stops 975, 977, 978 in the feedthrough housing 960, the parts of the system 901 can be secured and not slip even under applied pressure.

[0117] The feedthrough housing 960 defines the seal surface 962. The seal surface 962 is shaped along an interior surface of the feedthrough housing 960 where the compressible element 970 is compressed against the feedthrough housing 960. The seal surface 962 can be any conformation or shape based upon the shape of the compressible element 970. The seal surface 962 is a taper based upon the tapered shape of the compressible element 970.

[0118] In other implementations, as mentioned above, the electrical feedthrough 164 is provided for a reservoir that is held at a low pressure such as at a deep vacuum or a pressure that is below atmospheric pressure.

[0119] The above description includes examples of one or more implementations. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned embodiments, but one of ordinary skill in the art after being supplied with this disclosure will recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the described embodiments are intended to embrace all such alterations, modifications, and variations that fall within the spirit and scope of the appended claims.

[0120] The implementations can be further described using the following clauses:1. A detection system for a target material reservoir, the detection system comprising: a feedthrough housing associated with a wall of the target material reservoir, the feedthrough housing defining a seal surface; an electrically-conductive member extending through the feedthrough housing; and a compressible element that is electrically insulating, the electrically-conductive member being inside the compressible element, the compressible element contacting the feedthrough housing at the seal surface of the feedthrough housing, the interface between the feedthrough housing seal surface and a surface of the compressible element forming a hermetic seal when the compressible element is compressed.2. The detection system of clause 1, wherein the feedthrough housing defines a connecting surface.3. The detection system of clause 2, further comprising a compression device including a connecting surface that mates with the connecting surface of the feedthrough housing, wherein the compression device compresses the compressible element when its connecting surface is engaged with the connecting surface of the feedthrough housing.4. The detection system of clause 3, further comprising an electrical insulator between the compression device and the electrically-conductive member.5. The detection system of clause 3, wherein the connecting surface of the feedthrough housing and the connecting surface of the compression device are threaded mating surfaces.6. The detection system of clause 1, wherein the seal surface of the feedthrough housing is tapered toward an interior of the target material reservoir and the compressible element is tapered toward the interior of the target material reservoir when seated in the feedthrough housing.7. The detection system of clause 1, wherein the electrically-conductive member is a wire having a larger diameter portion facing an interior of the target material reservoir such that a shoulder of the wire abuts an end of the compressible element facing the target material reservoir.8. The detection system of clause 1, wherein the seal surface of the feedthrough housing is a face seal and the compressible element is a gasket seated between the seal surface and a flange of the wall.9. The detection system of clause 8, further comprising a seal stop positioned between the seal surface and the flange of the wall, the seal stop configured to limit compression of the compressible element.10. The detection system of clause 9, wherein the seal stop includes an insulating material.11. The detection system of clause 1, wherein the compressible element includes polybenzimidazole, polyimide, polyamide-imide, or combinations thereof.12. The detection system of clause 1, further comprising an electrical insulator between the wall and the electrically-conductive member.13. The detection system of clause 1, wherein the electrically-conductive member includes a refractory metal.14. The detection system of clause 13, wherein the electrically-conductive member includes molybdenum, tantalum, rhenium, or tungsten, and the target material in the target material reservoir includes tin.15. The detection system of clause 1, wherein the feedthrough housing is associated with a removable cap that forms the wall of the target material reservoir.16. The detection system of clause 1, wherein the feedthrough housing is associated with a side wall of the target material reservoir.17. The detection system of clause 1, wherein the compressible element is made of a material that: maintains compressibility at temperatures exceeding 200 °C, 250 °C, 300 °C, or within a range of 250 °C - 350 °C, and maintains a hermetic seal at a pressure differential of at least 6,000 kilopascals, at least 10,000 kilopascals, at least 25,000 kilopascals, or within a range of 6,000 kilopascals - 60,000 kilopascals.18. The detection system of clause 1, further comprising circuitry electrically connected to the electrically-conductive member and configured to measure a presence of target material in the target material reservoir.19. The detection system of clause 18, further comprising a control system in communication with the circuitry, the control system configured to adjust an amount of target material within the target material reservoir based on the measurement from the circuitry.20. The detection system of clause 19, wherein the control system is configured to determine one or more of: whether an amount of target material in the target material reservoir is greater than a maximum threshold and whether an amount of target material in the target material reservoir is less than a minimum threshold. 21. The detection system of clause 1, wherein the feedthrough housing is inside of and demountable from the wall of the target material reservoir.22. The detection system of clause 1, wherein the feedthrough housing is the wall of the target material reservoir.

[0121] The above-described implementations and other implementations are within the scope of the following claims.

Claims

CLAIMS1. A detection system for a target material reservoir, the detection system comprising: a feedthrough housing associated with a wall of the target material reservoir, the feedthrough housing defining a seal surface; an electrically-conductive member extending through the feedthrough housing; and a compressible element that is electrically insulating, the electrically-conductive member being inside the compressible element, the compressible element contacting the feedthrough housing at the seal surface of the feedthrough housing, the interface between the feedthrough housing seal surface and a surface of the compressible element forming a hermetic seal when the compressible element is compressed.

2. The detection system of claim 1, wherein the feedthrough housing defines a connecting surface.

3. The detection system of claim 2, further comprising a compression device including a connecting surface that mates with the connecting surface of the feedthrough housing, wherein the compression device compresses the compressible element when its connecting surface is engaged with the connecting surface of the feedthrough housing.

4. The detection system of claim 3, further comprising an electrical insulator between the compression device and the electrically-conductive member.

5. The detection system of claim 3, wherein the connecting surface of the feedthrough housing and the connecting surface of the compression device are threaded mating surfaces.

6. The detection system of claim 1 , wherein the seal surface of the feedthrough housing is tapered toward an interior of the target material reservoir and the compressible element is tapered toward the interior of the target material reservoir when seated in the feedthrough housing.

7. The detection system of claim 1, wherein the electrically-conductive member is a wire having a larger diameter portion facing an interior of the target material reservoir such that a shoulder of the wire abuts an end of the compressible element facing the target material reservoir.

8. The detection system of claim 1, wherein the seal surface of the feedthrough housing is a face seal and the compressible element is a gasket seated between the seal surface and a flange of the wall.

9. The detection system of claim 8, further comprising a seal stop positioned between the seal surface and the flange of the wall, the seal stop configured to limit compression of the compressible element.

10. The detection system of claim 9, wherein the seal stop includes an insulating material.

11. The detection system of claim 1 , wherein the compressible element includes polybenzimidazole, polyimide, polyamide-imide, or combinations thereof.

12. The detection system of claim 1, further comprising an electrical insulator between the wall and the electrically-conductive member.

13. The detection system of claim 1, wherein the electrically-conductive member includes a refractory metal.

14. The detection system of claim 13, wherein the electrically-conductive member includes molybdenum, tantalum, rhenium, or tungsten, and the target material in the target material reservoir includes tin.

15. The detection system of claim 1, wherein the feedthrough housing is associated with a removable cap that forms the wall of the target material reservoir.

16. The detection system of claim 1, wherein the feedthrough housing is associated with a side wall of the target material reservoir.

17. The detection system of claim 1, wherein the compressible element is made of a material that: maintains compressibility at temperatures exceeding 200 °C, 250 °C, 300 °C, or within a range of 250 °C - 350 °C, and maintains a hermetic seal at a pressure differential of at least 6,000 kilopascals, at least 10,000 kilopascals, at least 25,000 kilopascals, or within a range of 6,000 kilopascals - 60,000 kilopascals.

18. The detection system of claim 1, further comprising circuitry electrically connected to the electrically-conductive member and configured to measure a presence of target material in the target material reservoir.

19. The detection system of claim 18, further comprising a control system in communication with the circuitry, the control system configured to adjust an amount of target material within the target material reservoir based on the measurement from the circuitry.

20. The detection system of claim 19, wherein the control system is configured to determine one or more of: whether an amount of target material in the target material reservoir is greater than a maximum threshold and whether an amount of target material in the target material reservoir is less than a minimum threshold.

21. The detection system of claim 1, wherein the feedthrough housing is inside of and demountable from the wall of the target material reservoir.

22. The detection system of claim 1 , wherein the feedthrough housing is the wall of the target material reservoir.

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