High-frequency antenna access device for inductive coupling discharge device

Abstract

The invention discloses a high-frequency antenna access device for an inductive coupling discharge device, which is characterized in that one side of each of two support legs of a high-frequency antenna is connected to an upper cover plate of an ion source through a differential mode choke coil; the parasitic capacitors C0 and C0'on the other sides of the two supporting legs A1 are respectively connected with the differential mode choking coils L1 and L1 'in parallel, and the parallel resistance is infinite by adjusting the differential mode choking coils L1 and L1', so that the power fed in from the two supporting legs A1 of the high-frequency antenna cannot be shunted. In order to solve the problems that in the prior art, parasitic capacitors C0 and C0'shunt high-frequency current for driving inductive coupling discharging, and then the discharging efficiency is reduced and electromagnetic radiation is enhanced, differential mode choking coils L1 and L1 'are introduced, and inductive reactance of the choking coils is adjusted, so that the high-frequency current shunt effect of the parasitic capacitors is effectively restrained; and the equivalent impedance of the parallel branch tends to be infinite. The bypass of high-frequency current passing through the stray capacitor is effectively blocked, and high-frequency power can be efficiently fed into the discharge cavity.

Description

Technical Field

[0001] This invention relates to the fields of ion source technology and high frequency technology, and in particular to a high frequency antenna access device for an inductively coupled discharge device. Background Technology

[0002] High-current negative hydrogen ion sources are widely used in high-current proton accelerators, power semiconductor hydrogen ion implantation processes, and controlled nuclear fusion neutral beam injection heating. In high-frequency, high-current negative hydrogen ion sources that use high-frequency inductively coupled discharge to replace traditional hot cathode arc discharge to generate hydrogen plasma, the contradiction between current intensity and lifespan of the negative hydrogen ion source device is fundamentally resolved by eliminating the hot cathode structure immersed in the plasma.

[0003] For high-frequency inductively coupled discharge devices applicable to other charged particle beams, unlike devices that rely on capacitive coupling discharge and arc discharge, these inductively coupled discharge devices also have the advantages of high efficiency and long lifespan.

[0004] The high efficiency of the inductively coupled discharge device depends on the control of the specific coupling mode of the high-frequency drive discharge and the high efficiency of the high-frequency power feed itself. The coupling mode of the high-frequency drive discharge and the distribution of different discharge modes at different positions in the ion source discharge cavity also affect the efficiency of the high-frequency power feed itself.

[0005] The method of high-frequency antenna access directly affects the specific coupling mode and distribution of high-frequency driven discharge, thus being crucial to the performance, efficiency and lifespan of high-frequency inductively coupled discharge devices.

[0006] Problems with existing high-frequency antenna access devices, such as Figure 1 As shown, the parasitic capacitances C0 and C0' between the two legs A1 and the ion source cover plate 12 always exist. Specifically, C0 and C0' are the parasitic capacitances C1 and C1' of the enamel coating A2 applied to the two legs A1 of the high-frequency antenna, the parasitic capacitances C2 and C2' formed between the enamel coating A2 of the two legs A1 and the clamping block 11, and the parasitic capacitances C3 and C3' of the two clamping blocks 11 through which the two legs A1 of the high-frequency antenna pass. These three sets of series capacitances can be represented by parasitic capacitances C0 and C0'.

[0007] The parasitic capacitances C0 and C0' mentioned above will shunt the "high-frequency current that can actually be used to drive inductively coupled discharge" passing through the helical segment A3 of the high-frequency antenna, or simply cause the high-frequency power to directly form a local capacitively coupled discharge at the location where the parasitic capacitances C0 and C0' are formed, short-circuiting the helical segment A3 of the high-frequency antenna, greatly reducing the plasma density in the ion source discharge cavity, and generating severe electromagnetic radiation.

[0008] To address the shunting effect of parasitic capacitances C0 and C0', existing technologies employ an unbalanced short-circuit method between the two legs A1 of the high-frequency antenna and the upper cover plate 12 of the ion source. Figure 5-6 As shown, one of the two legs A1 of the high-frequency antenna is directly short-circuited to the ion source cover plate 12. After short-circuiting, the short-circuited leg A1 no longer faces the risk of high-frequency arcing and capacitive coupling discharge with the cover plate 12 because it is directly short-circuited to the ion source cover plate 12. However, the other high-frequency antenna leg A1, which is not short-circuited, bears the entire high-frequency power voltage drop of the plasma's overall load between it and the ion source cover plate 12. This significantly increases the risk of high-frequency arcing and capacitive coupling discharge between this leg A1 and the ion source cover plate 12, and also increases the high-frequency electromagnetic radiation between this leg A1 and the ion source cover plate 12. (If both legs are short-circuited to the ion source cover plate 12, a short circuit is directly formed between the two legs A1 of the high-frequency antenna, and most of the high-frequency power will be diverted through this short-circuit path, making it almost impossible to feed into the spiral section A3 of the high-frequency antenna as "the high-frequency current that can actually be used to drive inductively coupled discharge".) Summary of the Invention

[0009] This invention addresses the problems existing in the prior art by proposing a high-frequency antenna access device for an inductively coupled discharge (ICD) device. The first objective is to solve the problem that the parasitic capacitances C0 and C0' in existing high-frequency antenna access devices can shunt the high-frequency current that is actually used to drive the ICD through the spiral segment A3 of the high-frequency antenna. The second objective is to solve the problem that directly short-circuiting one of the two legs A1 of the high-frequency antenna to the ion source cover plate 12 causes the entire voltage drop of the high-frequency power to be applied between the other leg A1 and the ion source cover plate 12, thus drastically increasing the risk of high-frequency arcing and capacitive coupling discharge between the high voltage of leg A1 and the ion source cover plate 12.

[0010] To solve its technical problem, the present invention adopts the following technical solution: A high-frequency antenna access device for an inductively coupled discharge device is characterized in that: one side of each of the two legs (A1) of the high-frequency antenna is connected to the upper cover plate (12) of the ion source through differential mode chokes (L1) and (L1'), so that the parasitic capacitances (C0) and (C0') formed between the two legs (A1) of the high-frequency antenna and the upper cover plate (12) of the ion source are connected in parallel with the differential mode chokes (L1) and (L1'), respectively; by adjusting the differential mode chokes (L1) and (L1'), the parallel impedance between the two legs (A1) of the high-frequency antenna and the upper cover plate (12) of the ion source is almost purely resistive, and a large equivalent resistance is obtained near the operating frequency point f of the inductively coupled discharge device, thereby reducing the shunting of the power fed from the two legs (A1) of the high-frequency antenna on the parallel impedance.

[0011] Furthermore, the differential mode chokes (L1) and (L1') are each made of nickel-zinc ferrite magnetic rings of the same specifications and high-temperature wires of the same gauge and size.

[0012] Furthermore, by adjusting the differential mode chokes (L1) and (L1'), the parallel impedance between the two legs (A1) of the high-frequency antenna and the ion source cover plate (12) is made almost purely resistive. Specifically, the inductive reactances 2πfL1 and 2πfL1' introduced by the differential mode chokes (L1) and (L1') are canceled out by the capacitive reactances 1 / 2πfC0 and 1 / 2πfC0' of the parasitic capacitances (C0) and (C0') near the operating frequency f of the inductively coupled discharge device, thereby making the equivalent impedance between the two legs (A1) of the high-frequency antenna and the ion source cover plate (12) purely resistive, which is the equivalent parallel resistances R1 and R1' of the differential mode chokes (L1) and (L1').

[0013] Furthermore, to achieve a large equivalent resistance near the operating frequency f of the inductively coupled discharge device, specifically: the differential mode chokes (L1) and (L1') are wound with high-temperature wire of the same gauge and size on a nickel-zinc ferrite magnetic ring of the same specification. By adjusting the differential mode chokes (L1) and (L1'), the equivalent parallel resistances R1 and R1' of the differential mode chokes (L1) and (L1') can be made equivalent, and a large value can be obtained near the operating frequency f of the inductively coupled discharge device, thereby reducing the shunting of the power fed from the two legs (A1) of the high-frequency antenna on the parallel impedance.

[0014] Furthermore, the equivalent parallel resistances R1 and R1' are very small for DC, which makes the two legs (A1) of the high-frequency antenna and the ion source cover plate (12) short-circuited with DC. Therefore, they are always simultaneously raised to the DC high voltage potential or grounded, eliminating the possibility of DC high voltage arcing or arcing between the two legs (A1) of the high-frequency antenna and the ion source cover plate (12) from the root. Advantages and effects of the invention

[0015] 1. Effectively suppressing the high-frequency current shunting effect of parasitic capacitance: Addressing the problem in existing technologies where parasitic capacitances C0 and C0' shunt the high-frequency current driving inductively coupled discharge, leading to decreased discharge efficiency and enhanced electromagnetic radiation, this invention introduces differential-mode chokes L1 and L1', connected in parallel with parasitic capacitances C0 and C0' respectively. By adjusting the differential-mode chokes, the inductive reactances 2πfL1 and 2πfL1' of L1 and L1' cancel each other out with the capacitive reactances 1 / 2πfC0 and 1 / 2πfC0' of the parasitic capacitances at the operating frequency f. This results in the equivalent impedance of the parallel branch approaching pure resistivity, with the reactance approaching infinity. This effectively blocks the bypass of high-frequency current through the parasitic capacitance, ensuring that high-frequency power can be efficiently fed into the discharge cavity and loaded onto the helical segment A3 of the high-frequency antenna, serving as the "truly usable high-frequency current for driving inductively coupled discharge" to excite the plasma.

[0016] 2. Avoiding the potential risks caused by single-sided short-circuiting: Existing technologies that short-circuit one leg of the high-frequency antenna to the ion source cover plate eliminate capacitive coupling discharge on that side, but cause all high-frequency voltage to be applied to the other leg, significantly increasing the risk of high-frequency breakdown (arson) and capacitive coupling discharge between that leg and the cover plate. This invention, by symmetrically deploying differential-mode chokes on both legs, balances the distribution of high-frequency voltage on both sides, fundamentally avoiding instability caused by excessively high voltage on one side, and significantly improving the safety and long-term reliability of the device operation.

[0017] 3. Significantly Improved Inductively Coupled Discharge Efficiency and Plasma Performance: By effectively suppressing parasitic capacitance shunting as described above, this invention ensures that the vast majority of high-frequency power is concentrated and delivered to the helical segment A3 of the high-frequency antenna for efficient inductively coupled discharge. This not only directly improves energy utilization efficiency and plasma excitation efficiency but also results in higher plasma density, thereby optimizing the overall performance indicators of the ion source. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the parasitic capacitance distribution in a current high-frequency antenna access device. Figure 2 This is a schematic diagram of the high-frequency antenna legs, helical segment, and coating of the present invention; Figure 3 This is an equivalent schematic diagram of the differential mode chokes L1 and L1' connected to the upper cover plate according to the present invention; Figure 4 This is a detailed schematic diagram showing the differential mode chokes L1 and L1' connected to the upper cover plate according to the present invention; Figure 5 A schematic diagram of a single leg short-circuit in a current high-frequency antenna access device. Figure 1 ; Figure 6A schematic diagram of a single leg short-circuit in a current high-frequency antenna access device. Figure 2 . Detailed Implementation Innovation of this invention

[0019] Innovation Point 1: Actively canceling parasitic effects using an equivalent high impedance state. In traditional designs, the parasitic capacitances C0 and C0' between the high-frequency antenna legs and the grounding cover are an inherent defect that cannot be eliminated. In high-frequency environments, the capacitive reactance of these capacitances is small, forming a high-frequency current shunt path that "levitates" the ion source cover 12 to the high-frequency ground, causing significant power loss and high-frequency electromagnetic radiation. This invention employs an equivalent high impedance state: at the resonant point, the equivalent impedance Z of this parallel circuit theoretically reaches infinity (in practice, it will be a very high pure resistance due to factors such as component internal resistance). This means that at the target operating frequency, the original low-impedance shunt path becomes a high-impedance path, thereby greatly suppressing the shunt current. The key to achieving this technical effect is to precisely design and adjust the inductance of the differential-mode chokes L1 and L1' to make them resonate with the inherent parasitic capacitances C0 and C0' at the operating frequency. The direct effect of this invention is that the power that was originally wasted on parasitic capacitors C0 and C0' and the cover plate 12 of the ion source is lost and generates high-frequency electromagnetic radiation is converted into power that excites the inductively coupled plasma through the helical segment A3 of the high-frequency antenna (that is, more of it is used for R0 and L0, where R0 and L0 are the impedances brought by the antenna), thereby significantly improving the efficiency and power utilization of plasma discharge, while effectively controlling the high-frequency electromagnetic radiation of the inductively coupled discharge device.

[0020] Innovation Point Two: Systematic Symmetrical Design for Voltage Balance and Risk Dispersion: In traditional designs, shorting one leg completely solves the parasitic capacitance shunting and coupling discharge problems of that leg, but it disrupts the antenna's voltage symmetry. Under high-frequency voltage drive, almost all the high-frequency potential difference (voltage) of the entire antenna system will be applied to the leg that is not shorted. This causes a sharp increase in the voltage of that leg to ground, increasing the risk of high-frequency arcing (breakdown of air or working gas) and strong capacitive coupling discharge, creating a new and more serious reliability bottleneck. This invention adopts a symmetrical design, using the same differential-mode choke structure on both legs to maintain the electrical symmetry of the system. The symmetrical structure makes the high-frequency voltage amplitudes of the two legs "suspended at high frequency ground" to the ion source cover plate 12 similar. In this way, the total high-frequency voltage of the system is evenly distributed between the two legs A2 and the ion source cover plate 12, avoiding the situation of a single point bearing excessively high voltage. This solves the "parasitic capacitance shunting" problem mentioned in Innovation Point One. It also avoids the problems of "voltage concentration and arcing risk" caused by "single leg short circuit" in the background technology.

[0021] In summary, this application employs a balanced output and LC parallel resonant parasitic capacitance compensation technology using lumped / semi-lumped devices, solving the long-standing problems that have plagued the application of high-frequency inductively coupled discharge devices—power loss and voltage breakdown risk—and achieving a synergistic improvement in the efficiency and reliability of inductively coupled plasma sources. Design principle of the invention

[0022] Overview: The advantage of using high-temperature wire-wound nickel-zinc ferrite magnetic rings is that while achieving high inductance, the resistance to high-frequency power is also greater, resulting in lower shunt effect on the antenna. This means that the current and power on the line will not be too high, and the high-temperature wire itself has high temperature resistance, resulting in good stability during use. Since the differential mode chokes L1 and L1' are each wound with nickel-zinc ferrite magnetic rings of the same specifications and high-temperature wire of the same gauge and size, and their admittances are approximately equal, the high-frequency voltage division between the two legs A1 of the high-frequency antenna and the ion source cover plate 12 will also tend to be approximately equal, that is, it evenly shares the voltage drop on the overall load of the high-frequency antenna A and the plasma it drives. This reduces the high-frequency voltage that the structure between the single leg A1 and the ion source cover plate 12 needs to withstand to a minimum level, minimizing the risk of high-frequency arcing and local capacitive coupling discharge. The design principle is refined into the following two points: 1. Suppressing shunt current using LC resonance. ① Symmetrical connection: Connect the two legs A1 of the high-frequency antenna to the ion source cover plate 12 through independent differential-mode chokes L1 and L1' respectively. Thus, the parasitic capacitances C0 and C0' on each branch are connected in parallel with a choke. ② Resonance design: By precisely designing and adjusting the inductance parameters of the differential-mode choke, its inductive reactance jωL at the operating frequency f is made equal in magnitude and opposite in phase to the capacitive reactance 1 / jωC of the parasitic capacitance. ③ High impedance path: At the parallel resonance point, the reactance of the parallel circuit L1 / / C0 theoretically tends to infinity, and the overall equivalent impedance is a large equivalent resistance (R1 and R1'). This is equivalent to "setting up a checkpoint" on the shunt path, forcing most of the high-frequency current to flow only through the preset antenna helical segments R0 and L0, thereby significantly improving discharge efficiency and suppressing electromagnetic radiation.

[0023] 2. Symmetrical Design for Balanced Potential. ① Voltage Balance: Unlike the single-sided short-circuit scheme, this invention adopts a completely symmetrical topology. The two differential-mode chokes L1 and L1' are of identical specifications (e.g., wound with the same nickel-zinc ferrite magnetic ring and the same wire gauge at high temperature), ensuring consistent electrical characteristics of the two legs. ② Risk Dispersion: This symmetry ensures that the high-frequency voltage generated by the plasma load is evenly distributed between the two chokes. The high-frequency potential amplitudes of the two legs relative to ground (upper cover plate) are similar, avoiding excessive voltage on one leg, thus fundamentally eliminating the risk of high-frequency arcing caused by voltage concentration.

[0024] Based on the above design principles, this invention designs a high-frequency antenna access device for an inductively coupled discharge device, such as... Figure 3 , Figure 4 As shown, its features are: one side of each of the two legs A1 of the high-frequency antenna is connected to the upper cover plate 12 of the ion source through differential mode chokes L1 and L1', so that the parasitic capacitances C0 and C0' formed between the two legs A1 of the high-frequency antenna and the upper cover plate 12 of the ion source are connected in parallel with the differential mode chokes L1 and L1', respectively; by adjusting the differential mode chokes L1 and L1', the parallel impedance between the two legs A1 of the high-frequency antenna and the upper cover plate 12 of the ion source is almost purely resistive, and a large equivalent resistance is obtained near the operating frequency point f of the inductively coupled discharge device, thereby reducing the shunting of the power fed from the two legs A1 of the high-frequency antenna on the parallel impedance.

[0025] like Figure 3 , Figure 4 As shown, the differential mode chokes L1 and L1' are each made of nickel-zinc ferrite magnetic rings of the same specifications and high-temperature wires of the same gauge and size.

[0026] like Figure 3 , Figure 4 As shown, by adjusting the differential mode chokes L1 and L1', the parallel impedance between the two legs A1 of the high-frequency antenna and the upper cover plate 12 of the ion source is almost purely resistive. Specifically, the inductive reactances 2πfL1 and 2πfL1' introduced by the differential mode chokes L1 and L1' are, near the operating frequency f of the inductively coupled discharge device, canceled out by the capacitive reactances 1 / 2πfC0 and 1 / 2πfC0' of the parasitic capacitances C0 and C0', respectively. This makes the equivalent impedance between the two legs A1 of the high-frequency antenna and the upper cover plate 12 of the ion source purely resistive, which is the equivalent parallel resistances R1 and R1' of the differential mode chokes L1 and L1'.

[0027] like Figure 3 , Figure 4 As shown, to achieve a large equivalent resistance near the operating frequency f of the inductively coupled discharge device, specifically: the differential mode chokes L1 and L1' are wound with high-temperature wire of the same gauge and size on a nickel-zinc ferrite magnetic ring of the same specification. By adjusting the differential mode chokes L1 and L1', the equivalent parallel resistances R1 and R1' of the differential mode chokes L1 and L1' can be made equivalent, and a large value can be obtained near the operating frequency f of the inductively coupled discharge device, thereby reducing the shunting of the power fed from the two legs A1 of the high-frequency antenna on the parallel impedance.

[0028] like Figure 3 , Figure 4As shown, the equivalent parallel resistances R1 and R1' are very small for DC, which makes the two legs A1 of the high-frequency antenna and the ion source cover plate 12 short-circuited with DC. Therefore, they are always simultaneously raised to the DC high voltage potential or grounded, thus eliminating the possibility of DC high voltage arcing or arcing between the two legs A1 of the high-frequency antenna and the ion source cover plate 12.

[0029] It should be emphasized that the above specific embodiments are merely explanations of the present invention and are not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to the above embodiments without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A high-frequency antenna access device for an inductively coupled discharge device, characterized in that: One side of each of the two legs (A1) of the high-frequency antenna is connected to the top cover plate (12) of the ion source through differential mode chokes (L1) and (L1'), so that the parasitic capacitances (C0) and (C0') formed between the two legs (A1) of the high-frequency antenna and the top cover plate (12) of the ion source are connected in parallel with the differential mode chokes (L1) and (L1'), respectively. By adjusting the differential mode chokes (L1) and (L1'), the parallel impedance between the two legs (A1) of the high-frequency antenna and the top cover plate (12) of the ion source is almost purely resistive and a large equivalent resistance is obtained near the operating frequency point f of the inductively coupled discharge device, thereby reducing the shunting of the power fed from the two legs (A1) of the high-frequency antenna on the parallel impedance.

2. The high-frequency antenna access device for an inductively coupled discharge device according to claim 1, characterized in that: The differential mode chokes (L1) and (L1') are each made of nickel-zinc ferrite magnetic rings of the same specifications and high-temperature wires of the same gauge and size.

3. The high-frequency antenna access device for an inductively coupled discharge device according to claim 1, characterized in that: The method of adjusting the differential mode chokes (L1) and (L1') makes the parallel impedance between the two legs (A1) of the high-frequency antenna and the top cover plate (12) of the ion source almost purely resistive. Specifically, the inductive reactances 2πfL1 and 2πfL1' introduced by the differential mode chokes (L1) and (L1') cancel out the capacitive reactances 1 / 2πfC0 and 1 / 2πfC0' of the parasitic capacitances (C0) and (C0') near the operating frequency f of the inductively coupled discharge device, thereby making the equivalent impedance between the two legs (A1) of the high-frequency antenna and the top cover plate (12) of the ion source purely resistive, which is the equivalent parallel resistances R1 and R1' of the differential mode chokes (L1) and (L1').

4. The high-frequency antenna access device for an inductively coupled discharge device according to claims 1 and 2, characterized in that: To achieve a large equivalent resistance near the operating frequency f of the inductively coupled discharge device, the differential mode chokes (L1) and (L1') are wound with high-temperature wire of the same gauge and size on a nickel-zinc ferrite magnetic ring of the same specification. By adjusting the differential mode chokes (L1) and (L1'), the equivalent parallel resistances R1 and R1' of the differential mode chokes (L1) and (L1') can be made comparable, and a large value can be obtained near the operating frequency f of the inductively coupled discharge device, thereby reducing the shunting of the power fed from the two legs (A1) of the high-frequency antenna on the parallel impedance.

5. The high-frequency antenna access device for an inductively coupled discharge device according to claim 4, characterized in that: The equivalent parallel resistances R1 and R1' are very small for DC, so that the two legs (A1) of the high-frequency antenna and the upper cover plate (12) of the ion source are short-circuited to DC. Therefore, they are always simultaneously raised to the DC high voltage potential or grounded, thus eliminating the possibility of DC high voltage arcing or arcing between the two legs (A1) of the high-frequency antenna and the upper cover plate (12) of the ion source.

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