A dual liquid metal piston cylinder pressurized flow device for liquid metal target x-ray source

Abstract

The application relates to a double-liquid-metal-piston-cylinder pressurized flow supply device for a liquid-metal-target X-ray source, and belongs to the technical field of high-pressure flow supply of a liquid-metal-anode-target X-ray source. The technical problem to be solved is that reciprocating pressurized flow supply has flow gaps and pressure pulsations in a commutation neighborhood, leading to jet target line diameter fluctuation and unstable focal spots. Technical solution points are as follows: hydraulic piston cylinders are connected with first and second liquid-metal-piston cylinders through force transmission on the two sides of the axial direction, the liquid suction ports and the liquid discharge ports of the two cylinders are connected with a low-pressure supply side and a common high-pressure pipe through a liquid suction side and a liquid discharge side one-way valve group, and an energy accumulator is connected downstream of a liquid discharge convergence position; when the hydraulic piston reciprocates, the volumes of the two cylinders are complementary and alternately suction and discharge, the energy accumulator absorbs or releases medium volume in the commutation neighborhood, and bidirectional reciprocating motion is converted into unidirectional continuous high-pressure flow supply; the application also discloses a pre-charging, alternating pressurizing and controlled pressure releasing method. The application is mainly used for continuous and stable flow supply of a liquid-metal-jet-anode-target X-ray source.

Description

Technical Field

[0001] This invention relates to high-pressure power supply technology for liquid metal anode targets in X-ray sources, specifically to a booster power supply device and its operation method that uses common hydraulic power to form two liquid metal piston cylinders with complementary volumes and performs energy storage compensation after merging. Background Technology

[0002] Liquid metal jet anode targets need to be formed within a vacuum chamber with a small diameter, stable velocity, and continuous recovery capability. Compared to solid rotating anodes, liquid metal targets are constantly being updated, and the electron beam heat load is no longer concentrated on a fixed target surface. However, this also requires the upstream supply system to be able to continuously deliver liquid metal to the nozzle at higher pressures.

[0003] The stability of the supply pressure directly affects the jet diameter, jet centerline, and focal spot intensity. If the booster pump generates significant pulsation during reversal, the liquid metal at the nozzle outlet will exhibit periodic contraction or oscillation, which may manifest as brightness ripple, reconstruction artifacts, or decreased spatial resolution in the projected image.

[0004] For X-ray sources using free liquid metal jets as the anode target, the nozzle inlet needs to simultaneously meet the requirements of high static pressure and low flow ripple. The former determines whether the liquid metal can pass through the micropores to form a continuous liquid column with sufficient velocity, while the latter determines whether the jet diameter and center position within the electron beam's active region can remain stable during continuous exposure. Simply increasing the average pressure cannot eliminate the liquid supply gap at the moment of reversal; on the contrary, it may amplify valve impact and sealing load.

[0005] Liquid metals typically have high density, strong wettability, and pose a risk of corrosion to some metallic materials. If ordinary hydraulic pumps, gear pumps, or piston pumps come into direct contact with liquid metal, the lifespan of their seals, particle wear, and contamination control will be insufficient to meet the long-term operational requirements of X-ray sources.

[0006] Reviewing the development of liquid metal target supply technology, existing solutions have generally evolved along the following paths:

[0007] The first type of solution uses ordinary hydraulic pumps, gear pumps, or plunger pumps to directly pump liquid metal. This type of solution has a simple structure and low cost, but the pump body seals, bearings, and gears are directly exposed to the high-density, strongly wetted, and corrosive target medium. Wear particles can also enter the micro-orifice nozzle with the medium and cause blockage. Currently, this type of solution is only used in short-term experimental devices and is difficult to support continuous industrial-grade operation.

[0008] The second approach uses hydraulic oil to drive a single liquid metal piston cylinder, isolating the power medium from the target medium. This approach solves the medium compatibility problem, but the single-cylinder structure has an inherent interval between the liquid suction and discharge strokes: each discharge stroke is inevitably followed by a liquid suction stroke, and the nozzle end can only rely on the downstream reservoir to span the entire liquid suction cycle.

[0009] The third approach involves increasing the volume of the high-pressure reservoir on the basis of a single cylinder to mitigate intermittent flow. An excessively large reservoir volume will prolong the time for cold filling, pressure building, and shutdown depressurization, and increase the amount of high-pressure liquid metal and the risk of leakage; an excessively small volume will not be able to maintain continuous flow from the nozzle, and the filling and discharging process of the reservoir and the impact of valve opening and closing will still be transmitted to the nozzle inlet, forming a secondary source of pulsation.

[0010] The fourth type of solution uses two liquid metal piston cylinders controlled by independent actuators to work alternately. Because the stroke error and commutation phase of the two actuators accumulate during operation, there may be a supply gap where neither cylinder discharges liquid, or there may be pressure superposition where both cylinders discharge liquid simultaneously. Complex closed-loop synchronous control is required to barely maintain the connection, and the system cost and the number of failure points increase simultaneously.

[0011] However, for the engineering application of liquid metal target X-ray sources, the above-mentioned existing technical solutions have revealed the following technical defects that urgently need to be addressed:

[0012] (1) The inherent supply gap and reversing pulsation of reciprocating booster. In a single-cylinder reciprocating structure, the suction stroke accounts for about 30% to 50% of the complete cycle. At the moment of reversal, the nozzle inlet loses active liquid supply, and the pressure drop can reach 10% to 30% of the average supply pressure. The fluctuation of the supply pressure directly changes the jet diameter and jet centerline, which manifests as brightness ripple, reconstruction artifacts or decreased spatial resolution in the projected image. Simply increasing the average pressure or pump speed cannot eliminate the supply gap at the moment of reversal, but will instead amplify the valve impact and sealing load.

[0013] (2) The contradiction between energy storage compensation and system inertia. The scheme that relies on a large-capacity liquid storage tank to cross the liquid suction cycle has a significantly longer cold-state filling, pressure building and shutdown pressure relief time as the volume increases, and the high-pressure liquid metal storage and leakage risk increase simultaneously; the opening and closing impact of the liquid storage tank and valve group will also form a secondary pulsation source at the nozzle inlet, and the continuity of the flow supply is not truly obtained by the pump body. Once the liquid storage tank deteriorates, the overall flow supply quality deteriorates and is difficult to predict.

[0014] (3) Phase mismatch of independent dual-cylinder drive. If the two liquid metal piston cylinders are controlled by independent drivers, the stroke error and reversal phase accumulate with operation, and the supply gap and pressure superposition alternate. If there is no mechanical displacement constraint, it is difficult to maintain a repeatable minimum instantaneous flow rate in each reversal by relying solely on electronic control synchronization. Any drift in the synchronization sensing and execution links will be directly reflected as the periodic oscillation of the focal spot position.

[0015] (4) The separation boundary between the power medium and the target medium is unclear. Hydraulic oil can provide mature reversing, cooling and pressure regulation capabilities, but it should not enter the wetted cavity; gallium-based and other liquid metals have high density and pose a risk of corrosion to some metals and elastomers, so they should also not enter the hydraulic reversing valve. If the transmission components, dynamic seals and leakage inspection locations are not clearly defined, cross failures such as hydraulic oil mixing with the target medium, backflow of liquid metal corroding hydraulic components or valve core jamming will occur during long-term operation.

[0016] (5) Lack of continuity evaluation and fault location methods. The continuity evaluation of existing reciprocating pumps is mostly for conventional hydraulic media, and only the average pressure is considered; while liquid metal jet sources are also subject to the combined constraints of medium density, temperature, material compatibility and micro-orifice nozzle load. Two pumps with the same average pressure may be completely different in terms of minimum flow rate at reversal, valve backflow and residual gas compression. Operators cannot distinguish the three typical degradations of valve hysteresis, insufficient fluid replenishment and energy storage decay based on this, and maintenance can only rely on experience-based whole machine disassembly and inspection.

[0017] Therefore, the following technical challenges urgently need to be addressed in this field: how to use the same driving displacement to constrain two liquid metal piston cylinders to form a volume-complementary alternating pressurization under the premise of strict isolation between the power medium and the liquid metal, cut off the crosstalk between high and low pressure with a directional unidirectional flow distribution, and cover the instantaneous gap in the commutation neighborhood with common energy storage after the two discharge flows converge, so as to obtain a low-pulsation, diagnosable, and acceptable continuous flow supply under MPa-level supply pressure. Summary of the Invention

[0018] To address the aforementioned technical deficiencies, the present invention aims to provide a dual liquid metal piston cylinder pressurization and supply device and method for a liquid metal target X-ray source: two liquid metal piston cylinders are formed by complementary and alternating pressurization through common hydraulic drive, and the flow is unidirectionally distributed into a common high-pressure pipe through suction and discharge. The accumulator after the flow convergence reduces the commutation pulsation, so that the supply pressure covers 25MPa to 80MPa, the pressure pulsation rate is reduced to less than 3%, the minimum instantaneous flow rate in the commutation neighborhood is not less than 90% of the average flow rate, and reliable isolation between the hydraulic oil and the liquid metal medium is ensured during long-term operation.

[0019] This invention does not address liquid pressurization in the general sense, but rather the problem of high-density, potentially corrosive liquid metal being simultaneously affected by volumetric discontinuities and directional pressure waves during reciprocating pressurization. The supply gap that occurs at the end of single-cylinder discharge is directly transmitted to the micro-orifice nozzle, and simply increasing the pump speed will amplify the valve assembly impact. Therefore, it is necessary to establish a synergistic relationship at three levels: mechanical displacement, unidirectional flow distribution, and common energy storage.

[0020] Another problem to be solved is the unclear boundary between low-pressure replenishment and high-pressure discharge. If the suction side is connected to the high-pressure pipe during the half-cycle of discharge, or if the discharge side is opened in reverse during the half-cycle of suction, the high-pressure liquid metal will flow back to the supply end; if the piston cylinder is not fully filled with liquid before reversing the pressure, the mechanical stroke is mainly used to compress the residual gas and cannot form a repeatable discharge volume.

[0021] Therefore, this invention defines the force transmission relationship between the two liquid metal piston cylinders and the hydraulic piston, the directional relationship between the two sets of second check valves, and the positional relationship between the accumulator and the confluence point as the same technical concept, and evaluates the flow supply effect by the complete reciprocating cycle rather than a single steady-state pressure.

[0022] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0023] On one hand, the present invention provides a dual liquid metal piston cylinder pressurization and flow supply device for a liquid metal target X-ray source, including a hydraulic piston cylinder 101, a first liquid metal piston cylinder 102 and a second liquid metal piston cylinder 103 respectively disposed on both axial sides of the hydraulic piston cylinder 101 and connected to the piston for force transmission, a liquid suction side check valve group respectively connected to the liquid suction port of the two liquid metal piston cylinders, a liquid discharge side check valve group respectively connected to the liquid discharge port of the two liquid metal piston cylinders, a common high pressure pipe 503 connected to the two liquid discharge ports, and an accumulator 504 connected downstream of the confluence position; when the hydraulic piston moves in a first direction, one cylinder discharges liquid and the other cylinder draws liquid; when the hydraulic piston moves in a second direction, the two cylinders exchange the suction and discharge states, so that the liquid discharged from both cylinders is output unidirectionally to the jet system through the common high pressure pipe 503.

[0024] Optionally, the first liquid metal piston cylinder 102 and the second liquid metal piston cylinder 103 are located at opposite ends of the hydraulic piston cylinder 101, and the two ends of the common hydraulic piston are respectively connected to the two liquid metal pistons through the first piston rod 104 and the second piston rod 105. The central axes of the three cylinders are collinear, and they can also be arranged in parallel on a common load-bearing frame and connected by an equal displacement force transmission mechanism, so that the two liquid metal pistons can obtain effective volume changes in opposite directions under the same hydraulic piston displacement, without the need for separate synchronization between the two independent drives.

[0025] Optionally, the suction-side check valve group (i.e., the second suction-side check valve group 201) limits the liquid metal to flow into the two liquid metal piston cylinders only from the low-pressure supply side where the medium pump 603 is located, and the discharge-side check valve group (i.e., the second discharge-side check valve group 202) limits the liquid metal to flow into the common high-pressure pipe 503 only from the two liquid metal piston cylinders; each check valve is passively opened and closed by the pressure difference before and after the valve, without the need for the control system to issue synchronous commands to each of the four check valves one by one, and the valve component corresponding to each liquid metal piston cylinder can be disassembled and inspected individually, so that the decrease in unilateral discharge can be located to the corresponding suction resistance, discharge leakage or effective stroke.

[0026] Optionally, the accumulator 504 is a piston-type, diaphragm-type, or pneumatic accumulator, connected to the common high-pressure pipe 503 after the two drainage branches merge; its usable medium volume is estimated by the gap volume being equal to the product of the average flow rate of the jet system and the reversing gap time, and combined with the compressibility of liquid metal, the compliance of isolation elements, and the elasticity of pipeline, in engineering, it is taken as 0.5% to 20% of the theoretical discharge volume of a single drainage half-cycle, and the preload pressure is taken as 40% to 90% of the target minimum supply pressure, so that it releases the previously stored medium volume at the end of one half-cycle and reabsorbs the medium volume after drainage is established in the next half-cycle.

[0027] Optionally, the hydraulic piston cylinder 101 is connected to the oil supply circuit formed by the hydraulic oil pump 301, the first check valve 302 and the reversing valve 303, and to the oil return circuit formed by the second cooler 305 and the oil tank 306; the oil supply circuit can be connected to the oil return circuit through a solenoid valve for hydraulic oil pressure compensation or pressure relief during shutdown; the hydraulic oil circuit is responsible for changing the direction of the common piston movement and controlling the oil temperature, and does not directly participate in the flow direction selection of liquid metal, and the two circuits are completely isolated in terms of medium.

[0028] Optionally, the suction sides of the two liquid metal piston cylinders are connected to a medium pump 603. The medium pump 603 is connected to the medium container 601 via a coarse filter 602, providing the two liquid metal piston cylinders with low-pressure liquid metal required to overcome the pressure difference when the suction valve is opened and the resistance of the suction line. The coarse filter 602 intercepts larger particles before the liquid metal enters the precision valve port and piston cylinder. The pre-stage replenishment pressure is lower than the discharge pressure, and the two are naturally separated by a check valve.

[0029] Optionally, the hydraulic piston cylinder 101, the first liquid metal piston cylinder 102, and the second liquid metal piston cylinder 103 are located on a vibration isolation platform separate from the jet system and are connected to the jet system through a flexible high-pressure pipe, so that the reversing impact is not directly transmitted to the nozzle and scorch area; the booster flow assembly can complete the three acceptance tests of alternating liquid discharge, reverse sealing, and common energy storage independently before the whole machine, providing a clear boundary for the whole machine commissioning.

[0030] On the other hand, the present invention provides a method for supplying liquid metal jet system using the above-mentioned pressurization and flow supply device, comprising: a pre-charging step, wherein when the discharge side is in a low-pressure state, the medium pump pre-charges liquid metal into two liquid metal piston cylinders through the liquid suction side check valve group and confirms the effective filling volume; an alternating pressurization step, wherein the common hydraulic piston is driven to reciprocate, so that the two cylinders exchange suction and discharge states and the discharged liquid enters the common high-pressure pipe through the discharge side check valve; a confluence energy storage step, wherein the accumulator connected downstream of the confluence position receives or releases liquid metal in the reversing neighborhood to compensate for the difference between the instantaneous discharge volume and the flow consumption of the jet system; and a controlled shutdown step, wherein the electron beam permission of the jet system is first revoked, then the hydraulic oil supply pressure is reduced, the reversing is stopped, and the medium pump is stopped after controlled depressurization is completed in the common high-pressure pipe.

[0031] Compared to ordinary dual-cylinder parallel pumps, the key to this design lies not in the number of cylinders, but in the complementary volume changes in the two liquid metal chambers caused by a single hydraulic piston, the use of second one-way valve assemblies with opposite directions on both the suction and discharge sides, and the installation of an accumulator after the two discharge streams converge. Without any one of these three elements, the same unidirectional alternating pressurization and reversing volume compensation relationship cannot be achieved.

[0032] This forms a complete path from initial pressure supply, volumetric complementarity, unidirectional flow distribution to common energy storage. Claim 1 retains the common piston, two liquid metal cylinders, two-sided check valve groups, common high-pressure pipe and accumulator required to realize this path, while other oil circuits and vibration isolation structures are written into subordinate items step by step.

[0033] The beneficial effects of the technical solution provided by this invention include at least the following:

[0034] 1. Continuous flow supply with complementary volume under the same common driving displacement constraint. The common hydraulic piston constrains the volume changes of the two liquid metal piston cylinders to opposite directions under the same displacement. Continuous flow supply is first obtained by mechanical displacement complementarity: the liquid supply gap in the reversing neighborhood is compressed from the entire liquid suction stroke (about 30% to 50% of the cycle) of the single cylinder scheme to a narrow window of about 20ms to 80ms formed by the superposition of reversing valve switching and valve response; combined with the prototype test, the pressure pulsation rate of the common high pressure pipe under the rated 45MPa condition is reduced from about 25% of the single cylinder plus reservoir scheme to less than 3%, and the jet target diameter fluctuation is less than ±3%.

[0035] 2. Two-stage hydraulic-liquid metal pressurization and strict media isolation. The supply pressure on the liquid metal side is equal to the product of the hydraulic oil side pressure and the piston area ratio. When the area ratio is about 6.25, the hydraulic oil side only needs a conventional industrial pressure of 4MPa to 13MPa to obtain a high pressure of 25MPa to 80MPa on the liquid metal side. The directional, cooling and pressure regulation capabilities of the hydraulic oil are fully utilized, while the isolation boundary formed by the force transmission piston rod, dynamic seal and leakage observation space ensures that the hydraulic oil does not come into contact with the target medium and the liquid metal does not enter the directional valve, thus balancing pressurization capability and material compatibility.

[0036] 3. Directional compensation of the reversing gap by the common energy storage after the confluence. The accumulator is connected to the common pipe section after the two drainage flows converge. The same energy storage element covers two half cycles, avoiding the asymmetry between branches caused by connecting to a single branch. Its usable volume is estimated based on the gap volume being equal to the product of the average flow rate and the gap time. In the prototype, the compensation volume of about 5 mL will maintain the lowest instantaneous flow rate within the reversing valley value duration of about 45 ms at more than 90% of the average flow rate, and the reversing valley value pressure will not be lower than 95% of the average pressure.

[0037] 4. Diagnostic and Acceptable Functionality Based on Pressure Waveform Zoning. Liquid intake and discharge are defined by one-way valve assemblies in opposite directions. A fault on one side can be traced to a specific half-cycle. The pressure plateau, reversal trough, and symmetry of discharge on both sides indicate valve hysteresis, insufficient liquid replenishment, and energy storage attenuation, respectively. Combined with half-cycle tag records, a drop in discharge on one side exceeding 5% can pinpoint specific problems with liquid intake resistance, liquid discharge leakage, or effective stroke, avoiding the use of average pressure to mask instability within a cycle.

[0038] 5. Sub-assembly integration and overall focal spot stability. The pressurized power supply sub-assembly can independently complete the three acceptance tests of alternating liquid drainage, reverse sealing and common energy storage before the whole machine, and then connect to the jet system via a flexible high-pressure pipe for vibration isolation; with continuous exposure for 30 minutes at focal spot diameter ranges of 20μm to 100μm, the center position of the focal spot drifts by less than ±3μm, providing a unified continuous high-pressure power supply platform for continuous exposure in industrial CT and intermittent exposure in laboratory micro-CT. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the following description of the embodiments are briefly introduced; obviously, the accompanying drawings described below are only embodiments of the present invention, and those skilled in the art can obtain other related drawings based on these drawings without creative effort.

[0040] Figure 1This is a coaxial force transmission cross-sectional view of the hydraulic piston cylinder and the two liquid metal piston cylinders provided in the embodiment of the present invention. The figure shows the hydraulic piston cylinder 101, the first liquid metal piston cylinder 102, the second liquid metal piston cylinder 103, the first piston rod 104, and the second piston rod 105.

[0041] Figure 2 This is a flow distribution diagram of the second one-way valve group on the liquid suction side and the liquid discharge side provided in the embodiment of the present invention. The diagram shows the second one-way valve group 201 on the liquid suction side, the second one-way valve group 202 on the liquid discharge side, the first liquid suction port 203, the second liquid suction port 204, the first liquid discharge port 205, and the second liquid discharge port 206.

[0042] Figure 3 This is a hydraulic oil supply reversing and cooling return circuit diagram provided in an embodiment of the present invention. The diagram shows a hydraulic oil pump 301, a first check valve 302, a reversing valve 303, a hydraulic piston cylinder 304, a second cooler 305, and an oil tank 306.

[0043] Figure 4 This is a volume change comparison diagram of the dual liquid metal piston cylinder in opposite half cycles provided in the embodiment of the present invention. The diagram shows the first liquid discharge half cycle 401, the second liquid suction half cycle 402, the second liquid discharge half cycle 403, the first liquid suction half cycle 404, and the reversal position 405.

[0044] Figure 5 This is a structural diagram of two drain lines flowing into a high-pressure pipe and connected to an accumulator according to an embodiment of the present invention. The diagram shows the first drain line 501, the second drain line 502, the common high-pressure pipe 503, the accumulator 504, and the jet system interface 505.

[0045] Figure 6 This is a connection diagram of the medium container provided in the embodiment of the present invention, which is replenished by the coarse filter and the medium pump. The diagram shows the medium container 601, the coarse filter 602, the medium pump 603, the second one-way valve group 604 on the suction side, and two liquid metal piston cylinders 605. Detailed Implementation

[0046] The implementation method is described below from three observation levels: mechanical force transmission, unidirectional flow distribution, and common energy storage. The parameters in the examples are determined by material compatibility, design calculations, and prototype testing; unverified fixed values ​​are not considered universally necessary conditions.

[0047] Example 1: Assembly, clearance and low-pressure acceptance of the coaxial three-cylinder load-bearing body

[0048] This embodiment presents a structural configuration of a counter-rotating dual-cylinder booster pump. The hydraulic piston cylinders are arranged along a horizontal axis, with two liquid metal piston cylinders connected to their left and right ends respectively. The low-pressure pipe on the medium container side is connected to the second suction check valve assembly, and the high-pressure pipe side is connected to the second discharge check valve assembly.

[0049] Taking a prototype of a liquid metal jet anode target for industrial CT as an example, such as Figure 1 As shown, the inner diameter of hydraulic piston cylinder 101 is 50mm, and the effective stroke of the common hydraulic piston is 80mm; the inner diameters of the first liquid metal piston cylinder 102 and the second liquid metal piston cylinder 103 are both 20mm. The ratio of the effective area of ​​the liquid metal piston to the effective area of ​​the hydraulic piston is approximately 1:6.25. After the working pressure of 4MPa to 13MPa on the hydraulic oil side is amplified by the area ratio, a supply pressure of approximately 25MPa to 80MPa is formed on the liquid metal side. The theoretical discharge volume of a single half-cycle is approximately 25mL, and the reciprocating frequency is adjustable in the range of 0.1Hz to 2Hz, corresponding to an average supply flow rate of approximately 5mL / s to 100mL / s. The actual operating frequency is adjusted according to the nozzle flow consumption closed-loop, and it usually operates in the 0.2Hz to 1Hz range. The high-frequency range is used for rapid pressure building and pipeline flushing, which can cover the nozzle flow consumption requirements of target line diameters of 50μm to 500μm and jet velocities of 30m / s to 120m / s.

[0050] Example 1 employs a coaxial in-line structure. A hydraulic piston cylinder is located in the middle, with two liquid metal piston cylinders located at its axial ends. The three cylinders are kept aligned axially via end flanges or a shared load-bearing frame. The two ends of the common hydraulic piston are connected to the first and second piston rods, which extend into their respective liquid metal piston cylinders and drive the liquid metal pistons to move.

[0051] This embodiment uses a centrally located hydraulic piston cylinder and two end-capped liquid metal piston cylinders to form a coaxial assembly. The assembly datum is first established on the inner bore axis of the hydraulic cylinder and the positioning stops of the end caps at both ends. The two metal cylinders are pressed together by a common tie rod or a load-bearing frame. The piston rod is installed after measuring the axis deviation of the three cylinders to avoid forcibly absorbing the misalignment using the elasticity of the seals.

[0052] During assembly and acceptance, using the inner bore axis of hydraulic piston cylinder 101 as a reference, the coaxiality of the three cylinders along their entire length is measured using a dial indicator. The acceptance criterion is no greater than 0.05mm. The radial offset of the first piston rod 104 and the second piston rod 105 relative to their respective cylinder bores is no greater than 0.02mm. The common tie rod is pre-tightened in stages according to the hot-state dimensions, with a total axial deformation of no more than 0.1mm at room temperature and a relative deflection of no more than 0.02mm at both end caps, to prevent structural elastic deformation from being mistakenly identified as one-way valve leakage or piston jamming.

[0053] The effective stroke of the two liquid metal piston cylinders is defined by the piston end position and the dead chamber of the cylinder. While the two sides do not need to be of the same absolute size, they should achieve similar effective displacement under the same hydraulic piston displacement to prevent one half of the cycle from bearing a high output for an extended period.

[0054] The first and second piston rods are detachably connected to the common hydraulic piston. The connection transmits axial tensile and compressive forces but limits radial additional loads. The piston rods pass through the isolation end caps into the corresponding liquid metal cylinders. A leakage observation space is provided between the hydraulic chamber and the receiving chamber; if the seal on either side fails, the leaking medium first enters the observation space without directly entering the other medium circuit.

[0055] The clearance between the liquid metal piston and the cylinder wall is determined based on the thermal expansion at operating temperature, the viscosity of the medium, and the allowable internal leakage. After cold assembly, a temperature rise and no-stroke test is performed first to confirm that the piston does not jam during the process of rising from ambient temperature to operating temperature. Then, a dynamic seal or gap seal compatible with the target liquid metal is installed.

[0056] When the liquid metal piston and cylinder wall are sealed with a clearance, the single-sided clearance is set to 8μm to 15μm according to the thermal expansion difference at the operating temperature. In the prototype with gallium indium tin alloy as the working fluid and an operating temperature of 40℃ to 80℃, the measured internal leakage of a single cylinder corresponding to this clearance is less than 0.5% of the rated displacement. After assembly, a temperature rise and empty stroke reciprocating test of 20 cycles from 25℃ to 120℃ is performed first to confirm that there is no jamming or abnormal friction noise throughout the entire stroke before filling with liquid metal.

[0057] The hydraulic chamber and the liquid metal chamber are kept media-isolated. During assembly, first check that the two piston rods do not jam throughout their full stroke. Then, inject a test medium compatible with the working medium into each liquid metal chamber to confirm that piston movement will not allow the test medium to enter the hydraulic oil side. This check verifies the force transmission relationship and does not limit the specific sealing material to an essential feature of the independent claim.

[0058] The media isolation acceptance test is conducted in two stages: First, the receiving chamber is sealed, and the hydraulic chamber is pressurized to 21 MPa for 30 minutes, with a pressure drop not exceeding 2% and no oil traces in the leakage observation space. Then, while maintaining a low pressure in the hydraulic chamber, a test medium compatible with gallium-based alloys is introduced, and the pressure is gradually increased to 1.25 times the rated supply pressure, with each pressure stage held for 10 minutes. No test medium should appear in the observation space or on the exposed section of the piston rod. If any medium enters the observation space, the contaminated seals must be replaced; operation should not continue even after wiping away any traces of contamination.

[0059] Leakage checks were performed separately on the hydraulic oil side and the liquid metal side. For the hydraulic oil circuit, the directional valve, return oil passage, and second cooler were checked; for the liquid metal circuit, the two second check valve assemblies, high-pressure pipe, and accumulator were checked. The pressure holding results of one side were not used to replace the checks on the other side.

[0060] The second check valve assembly on the suction side is located near the low-pressure ports of the two piston cylinders, and its common inlet is connected to the medium pump; the second check valve assembly on the discharge side is located near the two high-pressure ports, and its two outlets converge into the common high-pressure pipe. Figure 2The arrows of the four valve elements point towards the piston cylinder or high-pressure pipe respectively. After assembly, each branch is used for forward flow and reverse pressure holding.

[0061] Two suction valves are positioned near the low-pressure ports of their respective cylinder chambers, while two discharge valves are positioned near the high-pressure ports. The valve core opening direction is verified on the assembly fixture using a physical arrow. After completion, a low-pressure inert test medium is passed through each of the four ports to check the forward opening and reverse pressure holding, avoiding the need to judge the direction solely based on the valve body's appearance.

[0062] The common high-pressure pipe connects to the accumulator after the two drain branches merge. To prevent the accumulator from responding only to local fluctuations on one side, no normally closed element capable of isolating either drain branch is installed between the junction point and the accumulator interface. The bending radius and connection strength of the high-pressure pipe are determined based on the operating pressure, liquid metal density, and temperature.

[0063] High-pressure pipe manifolds should avoid sudden expansion, blind holes, and low points that are difficult to drain. The accumulator interface should be located in the common pipe section after the manifold, so that it receives the common pressure wave formed by the alternating drainage from both sides, rather than only providing local buffering for one side.

[0064] The hydraulic oil pump draws oil from the tank, which then flows through the first check valve to the directional valve. The two working ports of the directional valve are connected to both sides of the hydraulic piston cylinder, and the return oil flows back to the tank via the second cooler. First, under a high-pressure load without liquid metal, the directional valve is switched at low speed to confirm that the effective stroke of the common piston in both directions meets the design value.

[0065] The common high-pressure pipe is first connected with a detachable test pipe section. The same volume of low-pressure test medium is introduced into the two branches respectively, and the pressure drop and residual amount of the branches are measured. If the difference exceeds the design tolerance, the elbows, valve seats and local diameter reductions are checked, instead of artificially creating symmetry by restricting the low-resistance branches.

[0066] Then start the medium pump to complete low-pressure filling of the two liquid metal piston cylinders when the common piston is centered. Slowly push the common piston to both ends and observe that the shrinking liquid metal cavity only discharges liquid from the drain valve, while the expanding liquid metal cavity only receives liquid from the suction valve. If reverse flow occurs, the valve direction should be corrected by depressurizing; do not increase the driving pressure to overcome the abnormal valve resistance.

[0067] The accumulator is installed on a short, straight pipe section downstream of the junction point, with its inlet oriented for easy removal of initial gas and disassembly / inspection. When using a piston-type accumulator, record the unloaded piston position; when using a diaphragm or bladder-type accumulator, perform a preload-side airtightness check. For any type, first verify under low pressure that the isolator does not release particles to the liquid metal side.

[0068] The structural acceptance record should include at least the effective stroke on both sides, the corresponding discharge volume, the forward opening state of the suction valve, the reverse sealing state of the discharge valve, and the accumulator connection position. Differences in discharge volume on both sides due to machining tolerances are permissible, but these differences should be explained by the piston area and stroke records, and it should be ensured that liquid can be discharged to the common high-pressure pipe in both half-cycles.

[0069] To verify the coaxiality of the force transmission, the common piston can be pushed with a small displacement without the check valve installed, and the radial offset of the two piston rods relative to the cylinder bore can be measured. If the offset exceeds the assembly allowance, the cylinder body connection surface should be adjusted instead of forcibly correcting it by increasing the sealing clamping force.

[0070] During low-pressure acceptance, the medium pump continuously replenishes fluid to both metal cylinders, and the hydraulic piston reciprocates at 10% to 30% of the rated frequency. Collect the discharge volume for each of the two half-cycles, calculate the discharge difference and the undischarged volume; if there is a significant deficiency on one side, first check the opening pressure difference of the suction valve on that side and the effective piston stroke.

[0071] Two liquid metal piston cylinders were calibrated for volume. The discharged test medium was collected between specified start and end positions, the effective displacement was calculated and compared with geometric calculations to identify dead space, piston rod volume occupation, or insufficient stroke.

[0072] Volume calibration was performed near the operating temperature of 60℃: with the position where the piston just leaves the mechanical buffer zone as the zero point of displacement, low-pressure discharged medium was collected at 10 stroke points and weighed to calculate the volume, and the effective area was obtained by linear fitting; the pairing criteria for the two liquid metal piston cylinders were that the deviation of the fitting slope was no greater than 1.5% and the deviation of the return stroke repeatability was no greater than 1%. The main structure and operating parameters of this embodiment are summarized in Table 1.

[0073] Table 1. Main Structure and Operating Parameters of the Booster Power Supply Device

[0074]

[0075] After the directional check of the check valve assembly is completed, maintain pressure according to the low pressure on the suction side and the high pressure on the discharge side. The test pressures for the suction valve and the discharge valve are different, and the boundary of the valve assembly is marked in the record to avoid extending the qualified conclusion of one valve to the entire assembly.

[0076] Without connecting the nozzle, gradually increase the back pressure, maintaining several complete reciprocating cycles at each stage while recording the piston rod temperature rise, observing space leakage, and monitoring the common pipe pressure. After reaching the design test pressure, instantaneous leak-free operation is not the sole qualification criterion; it is also necessary to confirm that the displacement during the two half-cycles does not continuously differentiate with the temperature rise.

[0077] After the accumulator is installed, check that the interface is located in the common busbar section and confirm that the passage from both drain branches to the interface is unobstructed. If either branch is mistakenly isolated before entering the accumulator, the same volume compensation will not be obtained during the commutation half-cycle.

[0078] Before completing the liquid metal test, all parts coming into contact with the liquid must undergo material compatibility verification and cleaning to prevent particles from damaging the check valve seat during initial operation. Assembly records and Figure 1 , Figure 2 and Figure 5 The markers correspond one-to-one.

[0079] The reciprocating frequencies of 0.1Hz to 10Hz and common pipe pressures of 0.5MPa to 80MPa given in this embodiment are only optional design windows for different prototypes. The actual combination must be determined based on the nozzle flow rate, cylinder diameter, material strength, and seal life, and the final application parameters must be written within the prototype boundaries confirmed by the inventor.

[0080] The assembly record should also specify the connection method between the two piston rods and the common hydraulic piston, as well as the remaining volume of the liquid metal chamber when the piston reaches the end of its stroke. This information is used to interpret the effective displacement, and the theoretical geometric volume is not directly regarded as the actual displacement.

[0081] To convert the machined dimensions into verifiable effective displacement, two liquid metal piston cylinders were calibrated after assembly using piston displacement and low-pressure discharge volume, respectively. Calibration was performed near the operating temperature, with the zero displacement point taken as the position where the piston just leaves the mechanical buffer zone. The effective area was fitted using multiple stroke points, and the end dead space, pre-valve residual fluid, and repeatable internal leakage were separated from the theoretical geometric volume. The pairing of the two cylinders was based on the fitting slope and return repeatability, rather than simply comparing the nominal cylinder diameter.

[0082] The load-bearing frame is designed with a closed force path in the direction of maximum thrust. The preload of the hydraulic cylinder end cap, metal cylinder end cap, and tie rod is checked against the hot-state dimensions. During inspection, the total axial deformation and the relative deflection of the two end caps are measured simultaneously. If the total deformation meets the strength requirements but the deflection causes lateral friction on the piston rod, the assembly is still considered unqualified. This avoids misjudging the effective stroke loss caused by structural elasticity as one-way valve leakage.

[0083] The hydraulic medium side and the liquid metal side are pressurized in two stages. First, the receiving chamber is sealed and the hydraulic chamber is pressurized, observing whether oil traces appear in the isolation space; then, the hydraulic chamber is kept at a low pressure, and the receiving chamber is pressurized step by step, checking the isolation space and the exposed section of the piston rod. The order of the two tests is used to identify the source of leakage, and any contaminated seals are replaced after any medium enters the isolation space; operation is not continued after wiping away traces.

[0084] Example 2: Alternating pressurization cycle of a volume-conserving organization

[0085] This embodiment uses a complete reciprocating cycle to illustrate the pressurization and flow supply process. The cycle begins when the hydraulic piston is in the middle position and both liquid metal piston cylinders are filled with liquid by the medium pump. The electron beam system and high-pressure nozzle remain closed during the pressure-building phase in this embodiment.

[0086] Example 2 begins with the low-pressure filling completed and the common hydraulic piston in the middle position. The medium pump continues to run, ensuring that the suction ports of the two liquid metal piston cylinders have an initial pressure sufficient to overcome pipeline resistance and the pressure difference when the suction valves open; at this point, the discharge side has not yet formed a formal injection load with the high-pressure nozzle.

[0087] Taking the parameters in Table 1, rated supply pressure of 45MPa, and reciprocating frequency of 1Hz as an example, a complete cycle is illustrated. After pre-charging, the initial pressure on the suction side stabilizes at 0.6MPa. After the reversing valve 303 switches, the common piston moves in the first direction at an average speed of about 0.16m / s. The pressure in the first liquid metal piston cylinder 102 rises to above the pressure of the common high-pressure pipe 503 within about 30ms. The first discharge valve opens, forming a first discharge platform of about 45MPa. The same displacement increases the volume of the second liquid metal piston cylinder 103. The second discharge valve remains closed due to the reverse pressure difference. The second suction valve opens to replenish liquid under the initial pressure of the medium pump 603. The two volume changes are mechanically complementary, while the two liquid flows are located at the high and low pressure boundaries.

[0088] After the directional valve switches to the first working position, hydraulic oil enters the first side of the hydraulic piston cylinder. The common piston moves to the second side, and the volume of the first liquid metal chamber decreases. As the pressure in the first liquid metal chamber exceeds the pressure in the common high-pressure pipe, the first drain valve opens; its suction valve closes due to the reverse pressure difference. Whether this half-cycle is completed is determined by the common piston reaching the predetermined effective stroke, rather than by the criterion of pre-filling fluid.

[0089] The same displacement increases the volume of the second liquid metal chamber. The second discharge valve remains closed due to the pressure of the common high-pressure pipe, while the second suction valve opens under the initial pressure of the medium pump. Therefore, the volume discharged from the first cylinder and the volume drawn into the second cylinder are mechanically related by the same common piston displacement, but the two liquid flows are located at different pressure boundaries.

[0090] The operation begins when both metal cylinders are filled with fluid and the common hydraulic piston is in a verifiable position. Before the start of the first half-cycle, the discharge valve of the first cylinder should be able to establish a high-pressure direction, and the suction valve of the second cylinder should be able to provide low-pressure fluid replenishment. These two conditions are formed by the pressure difference across the valve and the low-pressure supply state, respectively, and are not summarized by the same fixed end criterion.

[0091] When the hydraulic piston moves in the first direction, the effective volume of the first metal cylinder decreases by multiplying the piston area by the displacement. The volume discharged by this cylinder is composed of the actual discharge, internal leakage, and medium compression. Simultaneously, the volume of the second metal cylinder expands, and its intake is limited by the initial pressure of the medium pump and the flow resistance of the suction valve. Therefore, the changes in the two volumes are mechanically complementary, but the actual flow rates still need to be measured separately.

[0092] After the directional valve completes the oil circuit switching, the hydraulic piston moves in the second direction. The second cylinder switches from suction to discharge, and its discharge valve only opens when the pressure inside the cylinder is higher than the pressure in the common high-pressure pipe; the first cylinder is replenished with fluid through its suction valve after the pressure inside the cylinder drops to the low-pressure supply condition. This natural pressure differential distribution avoids the control system issuing synchronous commands to each of the four check valves one by one.

[0093] When the common piston approaches the end of the first half-cycle, the directional valve changes the hydraulic oil connection. After the reversal is completed, the first liquid metal chamber begins to draw in liquid, and the second liquid metal chamber begins to discharge liquid. The reversal criterion depends on the effective stroke of the hydraulic piston or the predetermined control logic of the directional valve. It does not require both sets of discharge valves to open simultaneously, nor is active overlap control a necessary condition in this embodiment.

[0094] Near the end of its stroke, the hydraulic circuit decelerates the piston to reduce reversing shock. At this time, the accumulator releases the previously stored medium to maintain downstream flow; the release amount should cover the common gap formed by the deceleration zone and the switching of the reversing valve, without requiring both drain valves to open at the same time.

[0095] During the continuous reciprocating process, the liquid discharged in the two half-cycles enters the common high-pressure pipe sequentially. The accumulator receives a portion of the liquid metal when the discharge rate temporarily exceeds downstream demand, and releases the liquid metal near the reversal point when downstream demand temporarily exceeds the instantaneous discharge rate. The energy storage effect can be evaluated by comparing the pressure peak-to-valley difference and the lowest instantaneous flow rate at the same reciprocating frequency before and after connecting the accumulator.

[0096] The pressure waveform of the common high-pressure pipe 503 was continuously recorded: the first and second drainage plateaus were 45.2 MPa and 44.8 MPa, respectively, with a peak pressure of 45.5 MPa, and two commutation valleys of 44.2 MPa and 44.4 MPa, respectively. The pressure pulsation rate (the ratio of peak-valley difference to average value) was approximately 2.9%, and the duration of the commutation valley was approximately 45 ms. The net position change of the accumulator 504 within one cycle was less than 5% of its working stroke, indicating that the average pumping output was balanced with the downstream flow consumption. In the control test with the accumulator 504 disconnected, the commutation valley dropped to 38.9 MPa at the same frequency, and the pulsation rate increased to approximately 16%. The baseline for the single-cylinder accumulator with the reservoir had a pulsation rate of approximately 25% under the same nozzle load. Typical control data are shown in Table 2.

[0097] Table 2 Comparison of supply pressure waveforms with and without a common energy storage device (rated pressure 45MPa, frequency 1Hz)

[0098]

[0099] The common pressure waveform is analyzed in sections: the first discharge plateau, the first reversing trough, the second discharge plateau, and the second reversing trough. Differences in the height of the two plateaus primarily indicate variations in cylinder area, stroke, or valve resistance; a decrease in both troughs primarily indicates insufficient energy storage capacity; if only one trough is abnormal, the corresponding reversing side should be checked first.

[0100] The volume balance of the complete cycle is calculated based on four independent quantities: the discharge volume of the first cylinder is 24.7 mL, the discharge volume of the second cylinder is 24.9 mL, and the discharge volume deviation between the two sides is 0.8%; the net volume change of accumulator 504 per cycle is less than 0.3 mL; the output volume of the downstream jet system is 49.4 mL, which is consistent with the total discharge volume of the two cylinders minus the net change in energy storage. If the net forward or backward movement of the accumulator per cycle exceeds 10% of its working stroke in the calculation, it is determined that the average pumping output and downstream loss are unbalanced. The balance is restored by fine-tuning the reciprocating frequency or the downstream opening, rather than masking the flow imbalance by increasing the accumulator preload pressure.

[0101] When performing volume balancing for a complete cycle, calculate the discharge volume of the first cylinder, the discharge volume of the second cylinder, the change in net accumulator volume, and the downstream output volume. If the accumulator cannot return to a similar position at the end of each cycle during stable operation, it indicates an imbalance between the average pump output and downstream flow consumption, requiring adjustment of the reciprocating frequency or the downstream opening.

[0102] The deceleration start point is set according to the minimum integral of the gap within the reversing window: In the range of 0.5Hz to 2Hz, the deceleration start point is gradually moved forward from 12mm before the end of the stroke to 20mm before the end. The gap volume (the integral of the difference between the downstream flow rate and the instantaneous supply flow rate of the two cylinders over time) is reduced from 2.1mL to 0.8mL. If it is moved forward further, there will be a risk of end impact. Therefore, the deceleration start point is set at 16mm to 18mm before the end of the stroke. The difference in gap volume between the two directions is controlled within 15%.

[0103] The reversing point of the complete cycle is determined by the available piston stroke, while the deceleration starting point is tuned based on the integral of the flow gap in the common high-pressure pipe. During the experiment, the deceleration starting point is gradually moved forward or backward, and the difference between the nozzle flow consumption and the actual flow supply of the two cylinders within the reversing window is calculated. Without end-impact, the position with the smallest gap integral and approximately symmetrical directions is selected. This tuning object is the volume gap, and a fixed delay time is not used as a substitute.

[0104] The accumulator's operating stroke is checked against the start and end positions of a complete cycle. Under stable operating conditions, both should fall within the same allowable range; a net forward shift per cycle indicates that the average boosted displacement is higher than the downstream flow consumption, while a net backward shift per cycle indicates insufficient flow supply. The controller then fine-tunes the reciprocating frequency or downstream operating point accordingly, but does not mask the persistent average flow imbalance by increasing the preload pressure.

[0105] The discharge volume in the first and second half-cycles can be indirectly compared by the high-pressure pipe outlet flow rate or the effective piston displacement. If an imbalance persists, prioritize adjusting the mechanical stroke or checking the corresponding check valve; do not mask the discharge difference by continuously increasing the hydraulic oil pressure.

[0106] A brief pressure change in the high-pressure pipe is permissible during commutation, but the accumulator should prevent this change from evolving into a significant flow interruption at the injection end. Peak, trough, and average values ​​can be compared over multiple consecutive cycles to determine the stability of pulse decay.

[0107] When a flow rate decrease occurs within only one half-cycle of drainage, the fault range can be narrowed down to the suction valve, drainage valve, and effective stroke on that side. First, compare the suction and discharge volumes on that side under low pressure, and then check the valve core hysteresis and piston movement separately to avoid misdiagnosing a single-sided flow distribution problem as a blockage in the common high-pressure pipe.

[0108] When a pressure spike occurs near the commutation point and the average displacement of the two half-cycles is similar, the commutation speed, displacement connection, and available accumulator volume should be checked first. By reducing the reciprocating frequency and observing whether the spike shifts accordingly, it is possible to distinguish between mechanical commutation impact and downstream fixed throttling.

[0109] In the first half-cycle, after the pressure in the common high-pressure pipe rises sufficiently to open the first drain valve, the first branch supplies liquid to the junction point; the second drain valve closes due to the reverse pressure differential. If the second drain valve leaks, some high-pressure liquid metal will enter the second cylinder that is currently drawing liquid, resulting in a drop in the common pressure and an abnormal increase in the amount of liquid drawn into the second cylinder.

[0110] If the pump outlet maintains pressure but both liquid metal chambers are underfilled, the fault is more likely located in the common suction path or temperature boundary. At this point, stop pressurizing, confirm that the filter is flowing, the piping is not solidified, and there is no common reverse pressure differential at the suction valve. After completing low-pressure filling, resume the cycle.

[0111] After troubleshooting, repeat the low-pressure pre-charge and flow direction confirmation for two and a half cycles before restoring high-pressure flow; do not restart directly from the interruption point at the original working pressure.

[0112] If a decrease in discharge occurs only in one and a half cycles, first check the corresponding suction valve, discharge valve, and effective stroke. If a decrease occurs simultaneously in both half cycles while the pump outlet is normal, check the common high-pressure pipe or downstream load. If the average flow rate remains essentially unchanged but the peak-to-valley difference increases, check the accumulator status. These three types of phenomena correspond to different physical links and should not be interpreted using the same fault conclusion.

[0113] The electron beam can be supplied by the jet system; this device only provides permissible conditions after the common pressure and flow rate reach the supply boundary. When shutting down, first cancel the electron beam, then allow the hydraulic piston to complete the current discharge section and reduce to a low-pressure cycle; subsequently stop the reversing and release the common pipe pressure to avoid locking the common piston in the high-pressure intermediate position.

[0114] After confirming the current supply boundary, open the electron beam: continuously expose for 30 minutes at a focal spot diameter range of 20μm to 100μm, with target line diameter fluctuation less than ±3% and focal spot center position drift less than ±3μm; if the common pressure pulsation rate rises to more than 5% due to a fault, periodic brightness ripples may appear in the projected image. At this time, cancel the electron beam permission and locate the fault according to the waveform partitioning process in Example 3. After the fault is eliminated, re-build the pressure from low-pressure pre-charge.

[0115] During a controlled shutdown, first shut off the electron beam and downstream injection permissions, then reduce the hydraulic oil supply pressure to a low-pressure circulation level, allowing the common piston to complete the current half-cycle before stopping the reversing. Subsequently, stop the media pump and handle any residual high pressure according to the equipment depressurization pathway. Restarting must begin with low-pressure filling and valve confirmation; it cannot be directly restored from the high-pressure reversing state before shutdown.

[0116] A complete test requires recording at least several reciprocating cycles. Recorded items include the common piston displacement or reversal time, the volume of fluid discharged from both sides, the pressure in the common high-pressure pipe, and the accumulator connection status. These independent quantities allow determination that the flow continuity is achieved through the complementary operation of the two cylinders, and that pressure smoothing is achieved through the common accumulator, avoiding the assumption that the entire structure is normal based solely on average pressure.

[0117] Before restarting, compare the static positions of the two cylinders with the initial position of the accumulator. If the common pressure does not drop to the maintenance boundary after shutdown, do not forcibly pump back the high-pressure medium by reversing the piston. Instead, use the prescribed pressure relief path to prevent the high-pressure branch from impacting the low-pressure vessel via the suction valve.

[0118] The commutation completion criterion, fluid replenishment completion criterion, and pressure stabilization criterion correspond to mechanical position, unidirectional flow, and common pipe pressure, respectively, and no longer use the same "stage end condition". Each criterion is only used for its physical object.

[0119] When switching from low-pressure circulation to high-pressure supply, several double half-cycles without electron beam are first completed to confirm that the drainage platforms, commutation valleys, and accumulator strokes on both sides are repeatable before the injection system is turned on. This verifies both the first half-cycle and the second half-cycle after commutation, preventing the equipment from starting from the side with better performance and missing insufficient liquid intake on the other side.

[0120] Example 3: Waveform-based zoned positioning valve hysteresis, insufficient fluid replenishment, and energy storage attenuation

[0121] This embodiment illustrates a device variant and verification method based on the technical concept that two liquid metal piston cylinders are driven by the same hydraulic reciprocating mechanism, the suction and discharge sides are limited by a second one-way valve group, and the discharge is smoothed by an accumulator.

[0122] The waveform is divided into four sections: the first drainage platform, the first reversal trough, the second drainage platform, and the second reversal trough. The acceptable range is defined as follows: platform pressure fluctuations should not exceed ±1.5% of the average value, and the height difference between the two platforms should not exceed 3%; the reversal trough should not be lower than 95% of the average pressure, and the time for the pressure to recover to the lower limit of the platform after the trough should not exceed 50ms; the discharge deviation between the two half-cycles should not exceed 3%. If any section exceeds the limit, the fault is located according to the section's indication, and instability within the cycle is not masked by the average pressure being acceptable.

[0123] Criteria and handling of valve hysteresis: Valve hysteresis is defined as follows: if the delay time of the opening point of the drain valve relative to the piston displacement is greater than 15ms, or if the opening displacement drifts by more than 10% of the effective stroke as the frequency increases. First, compare the pressure establishment position under three sets of conditions: low frequency, rated frequency, and increased frequency. If the opening displacement remains approximately constant while the opening time shortens with frequency, it indicates normal differential pressure opening. If the opening time is approximately fixed and the opening displacement drifts, it indicates valve core sticking or spring attenuation. The solutions are to clean the valve components, increase the medium temperature from 40℃ to 60℃-80℃ to reduce viscosity, or adjust the slope of the deceleration section.

[0124] Criteria and handling for insufficient liquid replenishment: If the discharge rate on one side decreases by more than 5% from the calibrated value in a single half-cycle while the outlet pressure of the medium pump 603 is normal, it indicates that the pressure difference at the opening of the suction valve on that side is too large, the resistance of the suction branch is increasing, or the effective stroke of the piston is lost; if the discharge rates on both sides decrease simultaneously while the initial pressure on the suction side is below 0.3 MPa, it indicates a common suction path. Check the pressure drop of the coarse filter 602 in sequence (replace the filter element if it exceeds 0.15 MPa), the liquid level in the medium container 601, and the temperature of the suction pipeline (not lower than 10°C above the melting point of the working medium). After troubleshooting, re-pressurize from the low-pressure pre-charge; do not directly restore the original working pressure from the interruption point.

[0125] Criteria and handling of energy storage attenuation: If the valley values ​​of both reversing cycles deepen simultaneously and the working stroke of accumulator 504 decreases by more than 20% compared to the initial record, it indicates a drop in preload pressure or a change in the compliance of the isolator. While maintaining constant frequency and downstream resistance, compare the valley pressures in three states: accumulator connected, bypassed, and re-preloaded. If the valley pressure recovers after re-preloading to 60% to 80% of the minimum supply pressure, preload drift is confirmed; if it does not recover, the isolator must be disassembled and inspected. It is prohibited to compensate for energy storage volume attenuation by increasing the reciprocating frequency, as this will amplify valve group impact.

[0126] The above zoning criteria are summarized in Table 3, which serves as a reference for rapid on-site location and maintenance.

[0127] Table 3 Pressure Waveform Zoning Diagnosis Comparison Table

[0128]

[0129] The diagnostic test simultaneously acquires common piston displacement, reversing valve commands, common high-pressure pipe pressure, and discharge volume for two and a half cycles. All channels use the same time reference, ensuring that pressure events are mapped to specific piston positions; recording only the average pressure will lose information on valve opening delay and reversing valley values.

[0130] If the first discharge platform is consistently lower than the second discharge platform, first compare the no-load discharge volume on both sides under the same low-pressure inlet conditions. If there is a difference under no-load conditions, check the stroke of the first cylinder, internal leakage of the seal, and the discharge valve; if the no-load volumes are close but diverge under pressure, then check the pressure drop and pressure-bearing deformation of the high-pressure valve in the first branch.

[0131] If the pressure recovery time is prolonged after reversing but the average platform value remains basically unchanged, focus on checking the reversing valve switching speed, hydraulic oil temperature, and sluggish opening of the drain valve. If the recovery time remains approximately constant after reducing the reciprocating frequency, it can be further confirmed that the fault originates from valve actuation rather than insufficient discharge.

[0132] Valve hysteresis verification does not involve disassembling the high-pressure system to directly observe the valve core. Instead, it compares the pressure build-up position under three sets of conditions: low frequency, rated frequency, and increased frequency. When the opening position relative to the piston displacement remains approximately constant while the time decreases with frequency, it indicates that the opening is mainly determined by differential pressure. When the opening time is approximately fixed and the displacement position drifts, it indicates that mechanical response or viscous resistance dominates. This determines whether to clean the valve components, adjust the temperature, or modify the switching speed.

[0133] If the discharge rate decreases with running time in both half-cycles, while the outlet pressure of the medium pump remains constant, the temperature of the common suction pipe, the pressure drop of the coarse filter, and the liquid level in the medium container should be checked. This phenomenon differs from unilateral valve hysteresis and cannot be compensated by adjusting the limit switch on one side.

[0134] The displacement consistency test measures the discharge volume for two and a half cycles under the same reversing frequency and initial supply pressure. If the difference exceeds the design allowable value, first check the effective area and stroke on both sides, then check for leakage in the check valve. Only when the mechanical displacement and valve sealing are normal should the overall output be changed by adjusting the hydraulic oil pressure.

[0135] The pulsation test first disconnects the accumulator from the common high-pressure pipe or places it in a state without effective compensation, and records the baseline pressure waveform; then, the accumulator is restored to its operating state, and the waveform is recorded under the same pump speed and downstream resistance. By comparing the peak-to-valley difference, the recovery time after reversal, and the lowest pressure, the effect of the accumulator can be separated from the alternating discharge effect of the dual cylinders themselves.

[0136] When both commutation valleys deepen simultaneously and the accumulator piston stroke decreases, it indicates a decrease in the available accumulator volume or a change in preload status. The test compares three states—accumulator connected, bypassed, and re-preloaded—while maintaining constant cylinder frequency and downstream resistance, to eliminate the possibility of nozzle load variations.

[0137] When a short-term spike occurs in the common pressure, check the hydraulic piston deceleration section and reversing timing. If the spike increases significantly with the reciprocating frequency, it indicates that dynamic impact is dominant; if the spike remains tied to a certain branch under a fixed downstream flow rate, check the delayed opening followed by sudden opening of the drain valve in that branch.

[0138] The check valve performance is assessed using a split-side pressure-maintaining method. First, isolate the first drain branch and observe the pressure drop in the common pipe. Then, isolate the second branch and retest. Subsequently, observe whether the liquid level rises on the low-pressure supply side. The leaking valve is determined by the location of the pressure drop, and it is not disassembled or inspected under high pressure.

[0139] The check valve performance was verified by maintaining pressure during shutdown. The common high-pressure line was kept at the predetermined test pressure, while the pump side was at low pressure. It was observed whether the liquid metal returned to the medium container via the suction branch. Subsequently, the drain branches on both sides were isolated to identify the specific leaking valve. After the test, the pressure was released as specified, and it was confirmed that the piston was in a safe, maintainable position.

[0140] The continuous-run version for industrial CT can extend the thermal equilibrium test, while the compact version for laboratory micro-CT can shorten the high-pressure tube, but neither changes the connection order of the two cylinders, two sets of unidirectional distribution, and common accumulator.

[0141] If hydraulic pistons and liquid metal pistons with different cross-sectional areas are selected for the equipment, pressure amplification can be achieved through the area ratio; after changing the area ratio, the piston rod force, sealing load, and displacement per cycle should be recalculated. The area ratio itself is not a substitute for continuous flow.

[0142] Example 3 illustrates the pump type selection and verification boundaries without altering the core connection relationships. The hydraulic piston and the two liquid metal pistons can have equal or unequal effective areas; when the area of ​​the liquid metal piston is smaller than the pressure-bearing area of ​​the hydraulic piston, pressure amplification can be achieved, but at the same time, the maximum liquid metal pressure needs to be checked according to the piston rod force and cylinder strength.

[0143] Accumulators can be piston, diaphragm, or pneumatic. When selecting an accumulator, the compatibility of the isolation element with the liquid metal and the operating temperature should be verified, and the accumulator's volume should cover the volume gap near the commutation point. Changing the type of accumulator does not alter its location on the common high-pressure pipe after the two liquid branch lines converge.

[0144] The liquid metal can be a gallium-based alloy or other suitable metal that remains liquid at the equipment's operating temperature. The materials used for piping, valve seats, and piston cylinders are determined through compatibility testing. The material selections given in this specification are for long-term operation, and specific grades not confirmed by the prototype are not included in the independent claims.

[0145] For continuous exposure in industrial CT and intermittent exposure in laboratory micro-CT, different piston displacements, commutation frequencies, and energy storage volumes can be selected. Both types of equipment maintain the same common hydraulic drive, unidirectional flow distribution for suction and discharge, and energy storage relationship after confluence, so they can still be implemented with the same structural features even when specific parameters are changed.

[0146] The pressure amplification test records the steady-state pressure on the liquid metal side under different hydraulic oil pressures, and compares the actual pressure ratio with the effective piston area ratio. If the deviation is too large, check for friction, internal leakage, and valve pressure drop.

[0147] The low-temperature start-up test verifies whether preheating is sufficient to keep the valve port and high-pressure pipe unobstructed; the high-temperature continuous test verifies the cooling of the hydraulic oil and the wetted materials. The two types of tests use different criteria and are not evaluated using the same average pressure.

[0148] After replacing the accumulator, repeat the pulse comparison to ensure that the change in type does not alter the common connection location. Record the available travel, preload status, and operating temperature as a basis for determining whether this type can be implemented.

[0149] Finally, the entire machine was tested by connecting it to the actual spray load. First, continuous target lines were confirmed without an electron beam, and then the electron beam was briefly turned on to observe the stability of the focal spot. Pump-side and jet-side anomalies were recorded separately.

[0150] Durability testing should cover the number of valve opening and closing cycles, hydraulic oil temperature stability, and the condition of the liquid metal side materials. If a decrease in displacement is observed with the number of cycles, check for valve seat wear, corrosion on wetted surfaces, and internal leakage in the hydraulic circuit.

[0151] Durability testing is organized according to the number of reversals, not just continuous time. Periodic checks are performed on hydraulic oil temperature, displacement over two and a half cycles, valve reverse leakage, and high-pressure pipe pulsation. When displacement continuously decreases with each reversal, whether the decrease is unilateral or bilateral can be used to determine valve seat wear, fluid replenishment resistance, or internal leakage in the hydraulic circuit.

[0152] Prototype durability data: After 200 hours of continuous operation at rated 45MPa and 1Hz, accumulating approximately 720,000 reversals, the displacement on both sides decreased by 1.3% and 1.1% respectively, the reversal valley pressure dropped by 0.6MPa, the hydraulic oil was maintained below 55℃ by the second cooler 305, and there was no medium in the leakage observation space; disassembly and inspection showed that the wear of the valve seat sealing surface was within the allowable range. Based on this, the maintenance intervals were adjusted as follows: the check valve assembly was disassembled and inspected every 1 million reversals, the accumulator preload was retested every 500 hours, and the coarse filter 602 was replaced when the pressure drop exceeded 0.15MPa.

[0153] Durability verification uses the number of reversals as the main variable, and records displacement difference, valley pressure, hydraulic oil temperature rise, and leakage observation space status at each stage. If the parameters show monotonic changes, worn parts should be disassembled and inspected before reaching the safe stopping condition, and maintenance intervals should be established for valve seats, seals, and energy storage isolation components.

[0154] After the durability test, the two liquid metal piston cylinders were restored to the same temperature and back pressure as the initial calibration, and the effective area, internal leakage, and valve reverse pressure holding were remeasured. Comparing only the online pressure at the end of the durability test would introduce temperature changes into the conclusion; after retesting under consistent conditions, the displacement slope, reversal valley value, and observation space status were used together as criteria for continuing to use or replacing the components.

[0155] After maintenance, the re-inspection should prioritize checking the valve direction and discharge rate, followed by the accumulator. This sequence can prevent leaks on one side of the valve from being masked by the accumulator temporarily smoothing the pressure.

[0156] After the variant test, the liquid level and liquid metal mass balance in the medium container are checked to confirm that the flow rate change is not caused by leakage or unrecovered medium, and then the differences between pump type and accumulator are evaluated.

[0157] For continuous industrial CT and intermittent micro-CT, different cylinder diameters, frequencies, and energy storage volumes can be used, but the acceptance testing still covers three aspects: mechanical volume complementarity, suction and discharge direction isolation, and post-merging compensation. As long as the relationship between these three aspects remains unchanged, specific dimensional changes will not alter the working principle of the device in this case.

[0158] After changing the type of liquid metal in the test apparatus, the melting point, viscosity, and material compatibility were reconfirmed, and the original pump speed and energy storage parameters were only used as initial references.

[0159] Fault localization uses semi-cycle tagging to store data. Each drainage operation records the corresponding cylinder number, start and end displacements, drainage volume, platform pressure, and the next reversing valley value, allowing anomalies of the same valve component to be clustered across multiple cycles. If an abnormal pressure valley value cannot be stably linked to a specific cylinder number, the common accumulator or hydraulic reversing valve is checked first; if it is consistently linked to the same cylinder number, then the suction / discharge valve and seal on that side are checked.

[0160] In summary, the device in this case ensures the mechanical precision of the two cylinders' complementary volumes through coaxial three-cylinder load-bearing assembly and clearance acceptance. It obtains continuous high-pressure flow at the MPa level through alternating pressurization working cycles with volume conservation. Furthermore, it enables valve lag, insufficient liquid replenishment, and energy storage attenuation to be located and restored separately through pressure waveform zoning diagnosis. The three levels share the same common hydraulic drive, the same set of unidirectional suction and discharge flow distribution relationships, and the same energy storage boundary after the convergence, forming a complete technical chain that distinguishes this case from parallel cylinder pumps and single-cylinder liquid storage solutions.

Claims

1. A dual liquid metal piston cylinder pressurization and flow supply device for a liquid metal target X-ray source, characterized in that, The system includes a hydraulic drive cylinder, a first liquid metal piston cylinder, a second liquid metal piston cylinder, a liquid suction unidirectional distribution assembly, a liquid discharge unidirectional distribution assembly, a common high-pressure pipe, and an accumulator. The first and second liquid metal piston cylinders are respectively connected to the same movable part of the hydraulic drive cylinder for force transmission, so that the two liquid metal working chambers produce effective volume changes in opposite directions in any direction of movement of the movable part. The liquid suction port of each of the two liquid metal working chambers is connected to a low-pressure supply end through the liquid suction unidirectional distribution assembly, and the liquid discharge port of each is connected to the common high-pressure pipe through the liquid discharge unidirectional distribution assembly. The liquid suction unidirectional distribution assembly and the liquid discharge unidirectional distribution assembly respectively define the flow direction of liquid metal entering and leaving the working chamber. The two discharge branches converge at the common high-pressure pipe, and the accumulator is connected between the confluence position and the jet system interface to receive or replenish the medium volume in the common high-pressure pipe during the reversal period when the two liquid metal working chambers exchange liquid suction and discharge states.

2. The dual liquid metal piston cylinder pressurization and flow supply device according to claim 1, characterized in that, The two liquid metal piston cylinders are located at opposite ends of the hydraulic piston cylinder, and are respectively connected to the piston of the hydraulic piston cylinder through the first piston rod and the second piston rod; the central axes of the three cylinders are collinear, or are arranged in parallel on a common load-bearing frame and connected by an equal displacement force transmission mechanism.

3. The dual liquid metal piston cylinder pressurization and flow supply device according to claim 1, characterized in that, The liquid suction side check valve group limits the liquid metal to flow into the two liquid metal piston cylinders only from the low-pressure supply side, and the liquid discharge side check valve group limits the liquid metal to flow into the common high-pressure pipe only from the two liquid metal piston cylinders; each check valve is passively opened and closed by the pressure difference before and after the valve, and the valve corresponding to each liquid metal piston cylinder can be disassembled and inspected individually.

4. The dual liquid metal piston cylinder pressurization and flow supply device according to claim 1, characterized in that, The accumulator is a piston accumulator, a diaphragm accumulator, or a pneumatic accumulator.

5. The dual liquid metal piston cylinder pressurization and flow supply device according to claim 1, characterized in that, The hydraulic piston cylinder is connected to the oil supply circuit formed by the hydraulic oil pump, the first check valve and the reversing valve, and to the oil return circuit formed by the second cooler and the oil tank.

6. The dual liquid metal piston cylinder pressurization and flow supply device according to claim 5, characterized in that, The oil supply circuit is connected to the oil return circuit via a solenoid valve, which is used to compensate for or depressurize the hydraulic oil.

7. The dual liquid metal piston cylinder pressurization and flow supply device according to claim 1, characterized in that, The first liquid metal piston cylinder and the second liquid metal piston cylinder are connected to a medium pump on their suction sides. The medium pump is connected to a medium container via a coarse filter to provide the two liquid metal piston cylinders with low-pressure liquid metal that overcomes the pressure difference when the suction valve is open.

8. The dual liquid metal piston cylinder pressurization and flow supply device according to claim 1, characterized in that, The hydraulic piston cylinder, the first liquid metal piston cylinder, and the second liquid metal piston cylinder are located on a vibration isolation platform separate from the jet system and are connected to the jet system through a flexible high-pressure pipe.

9. The dual liquid metal piston cylinder pressurization and flow supply device according to claim 1, characterized in that, The accumulator is connected to a common high-pressure pipe after the two drainage branches merge, and the available medium volume of the accumulator is set to cover the instantaneous liquid supply gap of the common high-pressure pipe during hydraulic piston reversal.

10. A method for supplying flow to a liquid metal jet system using the dual liquid metal piston cylinder pressurization and flow supply device according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. When the discharge side is under low pressure, the medium pump pre-fills the first liquid metal piston cylinder and the second liquid metal piston cylinder with liquid metal through the one-way valve group on the suction side, and confirms that both piston cylinders have formed an effective filling volume. S2. Drive the piston of the hydraulic piston cylinder to move in the first direction, so that the first liquid metal piston cylinder discharges liquid and the second liquid metal piston cylinder draws liquid. The discharged liquid metal enters the common high-pressure pipe through the corresponding discharge side check valve. S3. After the hydraulic piston reaches the reversing position, change the hydraulic oil supply and return direction to discharge the second liquid metal piston cylinder and draw in the first liquid metal piston cylinder. During the reversing process, keep the suction branch and the discharge branch isolated by their respective check valves. S4. The liquid metal discharged in the two half cycles is made to converge in the common high-pressure pipe, and the accumulator connected downstream of the convergence position receives or releases the liquid metal in the reversing neighborhood to compensate for the difference between the instantaneous discharge volume and the flow rate consumed by the jet system. S5. When shutting down, first cancel the electron beam permission of the jet system, then reduce the hydraulic oil supply pressure and stop the reversal. After the controlled depressurization of the common high-pressure pipe is completed, stop the medium pump.

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