CN110972383A - Ion generator and static eliminator - Google Patents

Abstract

The invention provides an ionizer and an electrostatic eliminator, wherein the electrostatic eliminator comprises a voltage source device and two ionizers which are respectively connected with the voltage device, the two ionizers are oppositely arranged, electrode needles on the two ionizers are parallel to each other, and the tip ends of the electrode needles face the same direction; the ion generator comprises a substrate and at least one electrode needle fixed on the substrate, at least one accommodating hole is formed in the substrate, and each accommodating hole accommodates one electrode needle; the tail end of each electrode needle is fixed on the substrate in the accommodating cavity, and the tip end of each electrode needle extends out of the accommodating cavity and is higher than the surface of the substrate. The static eliminator formed by the ionizer with the needle-hole structure (namely, the electrode needle is accommodated in the accommodating hole) is more easily used for transmitting airflow and ion flow based on the gap between the electrode needle and the accommodating hole in the needle-hole structure, so that the corona discharge can be stably generated in a nitrogen environment.

Description

Ion generator and static eliminator

Technical Field

The invention relates to the technical field of static elimination, in particular to an ionizer and a static eliminator.

Background

In order to prevent various disasters caused by electrostatic discharge (ESD), the international scientific and technological community has implemented a safe process of sealing nitrogen gas to prevent serious accidents such as fire and explosion in an oxygen-free and low-oxygen environment. However, how to realize the continuous operation of the electrostatic eliminator under the nitrogen environment is one of the difficulties that must be overcome by the scientific and technological community.

The sealed nitrogen safety process (also known as nitrogen inerting safety process, sometimes referred to as nitrogen seal) has been involved in many industrial processes, such as various powder preparations, pharmaceuticals, petrochemical processes, chemical synthesis, cleaning of ship oil tanks, cleaning of oil tank depots, fireworks manufacturing, gunpowder preparation, and the like. Various static elimination devices are often required in these fields. In recent years, the elimination of static electricity in a nitrogen atmosphere has been achieved using techniques such as nuclear radiation, ultraviolet rays, soft X-rays, corona discharge ion emission, and the like.

The ionizer in the static elimination device can generate positive and negative charges, which have a certain mobility if used for eliminating static charges, and drive the static charges which are not balanced on the surface of the static charged object (fixed object or static object). Controlling the generation of charge carriers that are generated in these gases is critical to achieving static elimination.

Corona discharge, which is achieved in high purity nitrogen, has been known for many years. In order to obtain the basic data of such corona discharge, efforts have been made to purify nitrogen, obtain a gas chamber of a certain degree of cleanliness, and prevent gas leakage or outgassing. The negative charge carriers generated in the corona discharge are free electrons and have a higher mobility than the positive charge carriers generated at the same time. The free electrons will adsorb to oxygen or other electronegative gaseous impurities (electrons). The mobility of these negative charge carriers directly affects the following factors: ionic current, spark discharge conditions, charge transfer and other factors can even significantly alter the composition of the environment. In order to ensure that the objective of static elimination in industrial applications is successfully achieved, the ionizer in the static elimination device must be sufficiently controllable with various ion mobilities.

In various kinds of discharge techniques (corona discharge, nuclear radiation, ultraviolet rays, X-rays), positive ions and free electrons are generated and occur in pairs. However, the ion balance of these ionizers is not easily controlled, especially in pure nitrogen gas with a wide temperature range (temperature range: 213K (i.e., -60 ℃) to 433K (i.e., 160 ℃) (note: the temperature here is uniformly in absolute temperature scale K, not in Celsius, because all the involved physical formulas are absolute temperature scales.

In order to solve the problems that the ion balance is not easy to control and the static elimination in the nitrogen environment cannot be realized by using an ionizer in the static elimination equipment in the prior art, the technical personnel in the field are always searching for a solution.

Disclosure of Invention

The invention aims to provide an ionizer and a static eliminator, which are used for solving the problems of the static eliminator in the prior art.

In order to solve the above technical problems, the present invention provides an ionizer comprising: the electrode needle holder comprises a base body and at least one electrode needle fixed on the base body, wherein at least one accommodating hole is formed in the base body, and each accommodating hole accommodates one electrode needle; the tail end of each electrode needle is fixed on a base body in an accommodating hole, and the tip end of each electrode needle extends out of the accommodating hole and is higher than the surface of the base body.

Optionally, in the ionizer, the ionizer further includes a voltage source connection terminal disposed on one side of the base body, and the voltage source connection terminal is connected to the tail ends of all the electrode pins through a lead.

Optionally, the ion generator further includes an airflow port disposed on one side of the substrate, the airflow port is communicated with the accommodating cavity, and the airflow port and the voltage source connection terminal are symmetrically disposed with respect to the substrate.

Optionally, in the ion generator, the accommodating cavity is funnel-shaped.

Optionally, in the ionizer, all the electrode needles are parallel to each other and perpendicular to the surface of the substrate, and all the electrode needles are tungsten needles.

Optionally, in the ion generator, the diameter range of the electrode needle is 0.20mm to 0.30mm, and the distance between two adjacent electrode needles is 57mm to 58 mm.

The present invention also provides a static eliminator suitable for static elimination in a nitrogen atmosphere, the static eliminator comprising:

the ion source device comprises a voltage source device and two ion generators which are connected with the voltage source device respectively, wherein the two ion generators are arranged oppositely, electrode needles on the two ion generators are parallel to each other, and the tip directions of the electrode needles are the same.

Optionally, in the static eliminator, a length extending direction of each ion generator is downwardly inclined at an angle ranging from 17 ° to 20 ° with respect to a horizontal direction.

Optionally, in the static eliminator, voltage source connection terminals of two ionizers are located on the same side, and a voltage source connection terminal of one ionizer is connected with a positive electrode of the voltage source device to form a positive voltage ionizer; and the voltage source connecting terminal of the other ionizer is connected with the negative electrode of the voltage source device to form a negative voltage ionizer.

Optionally, in the static eliminator, the distance between the two ionizers ranges from 28mm to 29 mm.

In the ionizer and the static eliminator provided by the invention, the static eliminator comprises a voltage source device and two ionizers respectively connected with the voltage device, the two ionizers are oppositely arranged, and electrode needles on the two ionizers are parallel to each other and the tips of the electrode needles face the same direction; the ion generator comprises a substrate and at least one electrode needle fixed on the substrate, at least one accommodating hole is formed in the substrate, and each accommodating hole accommodates one electrode needle; the tail end of each electrode needle is fixed on the substrate in the accommodating cavity, and the tip end of each electrode needle extends out of the accommodating cavity and is higher than the surface of the substrate. The static eliminator formed by the ionizer with the needle-hole structure (namely, the electrode needle is accommodated in the accommodating hole) is more easily used for transmitting airflow and ion flow based on the gap between the electrode needle and the accommodating hole in the needle-hole structure, so that the corona discharge can be stably generated in a nitrogen environment.

On the other hand, based on the airflow port on the ionizer, blowing of clean dry air or nitrogen can be realized, and the airflow is distributed in a forced ventilation mode, so that the gas in the electrostatic eliminator flows, and the transmission of charge carriers is enhanced.

On the other hand, the length extension direction of each ion generator is inclined downwards by 17-20 degrees relative to the horizontal direction, so that the flowing direction of gas and the flowing direction of transferred charge carriers can be effectively guided to face a charge elimination object, and the charge elimination efficiency is improved.

Drawings

FIG. 1 is a schematic diagram of a typical I-V curve for positive and negative voltage ionizer ion emission in air;

FIG. 2 is a schematic diagram of a typical I-V curve for positive and negative voltage ionizer ion emission in nitrogen;

FIG. 3 is a graphical representation of charge decay time versus ion current for positive and negative voltage ionizers;

FIG. 4 is a front view of an electrostatic charge remover according to an embodiment of the present invention;

FIG. 5 is a side view of FIG. 4;

FIG. 6 is a schematic of a charge decay curve obtained using the ionizer of the present invention;

fig. 7 is a schematic graph of the decay time of the charge obtained using the ionizer of this invention.

In fig. 4 and 5: 1-an ionizer; 10-a substrate; 11-electrode needle; 100-holding the acupoint; 12-voltage source connection terminal; 13-an airflow port; 2-gas channel.

Detailed Description

The ionizer and the static eliminator according to the present invention will be described in further detail with reference to the accompanying drawings and embodiments. Advantages and features of the present invention will become apparent from the following description and from the claims. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.

Certain terms are used throughout the description and claims to refer to particular system components. As one skilled in the art will appreciate, different companies may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the description and claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to …".

As used in this application and the appended claims, the terms "a," "an," "the," and/or "the" are not intended to be inclusive in the singular, but rather are intended to be inclusive in the plural unless the context clearly dictates otherwise. In general, the terms "comprises" and "comprising" merely indicate that steps and elements are included which are explicitly identified, that the steps and elements do not form an exclusive list, and that a method or apparatus may include other steps or elements.

Furthermore, each of the embodiments described below has one or more technical features, and thus, the use of the technical features of any one embodiment does not necessarily mean that all of the technical features of any one embodiment are implemented at the same time or that only some or all of the technical features of different embodiments are implemented separately. In other words, those skilled in the art can selectively implement some or all of the features of any embodiment or combinations of some or all of the features of multiple embodiments according to the disclosure of the present invention and according to design specifications or implementation requirements, thereby increasing the flexibility in implementing the invention.

The present invention will be described in more detail with reference to the accompanying drawings, in order to make the objects and features of the present invention more comprehensible, embodiments thereof will be described in detail below, but the present invention may be implemented in various forms and should not be construed as being limited to the embodiments described.

The design process of the ionizer of this invention is as follows:

on the basis of a corona discharge form comparison test of the ionizer in air and nitrogen, the ionizer with a needle-hole structure (namely, an electrode needle is accommodated in an accommodating hole) is determined through a corresponding ion balance test and an attenuation performance test (which are basic requirements of the electrostatic eliminator and cannot be reduced even in a nitrogen environment), and further the basic structure of the electrostatic eliminator in the nitrogen environment is determined.

Specifically, referring to fig. 1 and 2, fig. 1 is a schematic diagram of a typical I-V curve of ion emission of a positive and negative voltage ionizer in air; FIG. 2 is a schematic diagram of a typical I-V curve for positive and negative voltage ionizer ion emission in nitrogen. As shown in fig. 1 and 2, positive and negative high voltage corona ion emission tests were performed simultaneously in air and nitrogen using the same electrode structure, and corresponding current-voltage curves, i.e., I-V curves, were plotted. In the data presented on the curves in fig. 1 and 2, the current was averaged over time, and analysis of the curves revealed the following results for ionizer development:

1) for positive and negative voltage ionizers, the starting voltage of the positive corona discharge in air is about 3.7 kV; the starting voltage of the negative corona discharge is about 3 kV; in nitrogen, the initial voltage difference of the positive and negative corona discharges is not much the same, approximately at 4.2 kV.

2) For a positive voltage ionizer, the I-V curves formed in air and in nitrogen are almost the same (refer specifically to the difference in the vertical scale in fig. 1, 2).

3) For the negative voltage ion generator, when the air environment is replaced by the nitrogen environment, the corona current with negative polarity is observed to be greatly different and has the potential of being obviously enhanced, and the maximum corona current reaches even 175 muA which is six or seven times that in the air environment.

4) For the I-V curve in nitrogen, the current increases monotonically with voltage, but remains stable even at high nitrogen flow levels.

In summary, a significant enhancement of the corona current of negative polarity is to be expected, due to: in the simplest model, referring to equation (1), the current density J of the ionizer is proportional to the carrier mobility μ, the carrier charge concentration ρ, and the electric field strength E, while the mobility of the negative charge carriers is increased in nitrogen during this experiment, so it is judged that the corona current of negative polarity is significantly enhanced.

J＝ρ·μ·E (1)

In typical air and nitrogen environments, corona discharge is characterized as being sufficiently stable and controllable as long as the static eliminator reaches steady state operation. Since the carrier mobility μ and the carrier charge concentration ρ vary with temperature and gas composition in the present embodiment. The voltage source arrangement and control system must allow for enhancement of the negative charge carrier current, particularly as carrier mobility and concentration changes occur.

Based on the comparative test, the structure of the electrostatic eliminator applicable to the nitrogen environment is determined through a plurality of tests, corresponding ion balance tests and attenuation performance tests. Referring to fig. 4 and 5, fig. 4 is a front view of the electrostatic eliminator in this embodiment; fig. 5 is a side view of fig. 4. As shown in fig. 4 and 5, the static eliminator of the present invention comprises: the ion source device comprises a voltage source device (not shown in the figure) and two ion generators 1 respectively connected with the voltage source device, wherein the two ion generators 1 are oppositely arranged, electrode pins 11 on the two ion generators 1 are parallel to each other, the tip directions of the electrode pins 11 are the same, and a gas channel 2 is defined by the two ion generators 1. Wherein each ionizer 1 includes: the electrode needle assembly comprises a base body 10 and at least one electrode needle 11 fixed on the base body 10, wherein at least one accommodating hole 100 is formed in the base body 10, and each accommodating hole 100 accommodates one electrode needle 11; the tail end of each electrode needle 11 is fixed on the substrate 10 in a receiving cavity 100, and the tip end of each electrode needle 11 extends out of the receiving cavity 100 and is higher than the surface of the substrate 10 (i.e. a needle-cavity structure is formed). Further, the surface of the substrate 10 is provided with an insulating layer, the insulating layer is made of highly insulating glass fiber and is made into a fabricated structure, and in this case, the tip of the electrode needle 11 is higher than the surface of the insulating layer. Based on the gap between the electrode needle 11 and the receiving cavity 100 in the needle-cavity structure, it is easier to transmit the air flow and the ion flow, thereby realizing the stable generation of corona discharge in the nitrogen environment.

Further, the ionizer 1 further comprises a voltage source connecting terminal 12 disposed on one side of the substrate 10 and an airflow port 13 disposed on the other side of the substrate 10, wherein the voltage source connecting terminal 12 is connected with the tail ends of all the electrode pins 11 through a conducting wire; the airflow port 13 is communicated with the accommodating cavity 100, and the airflow port 13 and the voltage source connecting terminal 12 are symmetrically arranged relative to the base body 10. The ionizer 1 can perform forced ventilation to distribute its air flow based on the air flow port 13 thereon. In order to facilitate the control of the air flow rate of the ionizer 1, a monitoring instrument and a flow control instrument may be provided at the air flow port 13 to perform the control of the air flow rate according to the monitored data at any time.

As shown in fig. 5, the voltage source connection terminals 12 of two ionizers 1 are located on the same side, wherein the voltage source connection terminal 12 of one ionizer 1 is connected with the positive electrode of the voltage source device to form a positive voltage ionizer; the voltage source connection terminal 12 of the other ionizer 1 is connected to the negative electrode of the voltage source device to constitute a negative voltage ionizer, which is performed. The distance between the two ionizers 1 is in the range of 28mm to 29mm, preferably 28.5 mm. In this embodiment, preferably, the ionizer 1 located above in fig. 5 is powered by the positive high voltage of the voltage source device, and the ionizer 1 located below is powered by the negative high voltage of the voltage source device, in this embodiment, all the electrode needles 11 on the ionizer above are collectively referred to as an upper needle row, and all the electrode needles 11 on the ionizer 1 below are collectively referred to as a lower needle row.

Preferably, the voltage source device is a DC voltage source, and the time-averaged emission current is measured using a SIMCO TI800 digital ammeter, which is connected to the upper and lower pin headers by high voltage lines. Such currents consist of direct and pulsed currents, and the carriers they generate contribute to the gas flow, blowing towards the target. Preferably, the voltage source means is selected as SIMCO's IBC-20 with current control for each polarity, the maximum output being limited to tens of microamperes for safety purposes.

In this embodiment, referring to fig. 5, the accommodating cavity 100 is funnel-shaped, and a gap exists between the accommodating cavity 100 and the electrode needle 11; preferably, the number of the electrode needles 11 is four, and all the electrode needles 11 are parallel to each other and perpendicular to the surface of the substrate 10; preferably, the electrode needle 11 is made of tungsten wire (i.e., a tungsten needle). The diameter range of the electrode needle 11 is 0.20 mm-0.30 mm, the distance L between two adjacent electrode needles 11 is 57 mm-58 mm, and the preferable distance is 57.5 mm.

Preferably, the length extension direction of each ionizer is downwardly inclined at an angle ranging from 17 ° to 20 ° with respect to the horizontal direction, and preferably, at an angle of 18 ° in the present embodiment, so as to guide the gas flow and transfer the charge carriers to be emitted toward the objects for removing electricity, thereby improving the efficiency of removing electricity.

For a better understanding of the invention, the following experimental analyses were carried out with nitrogen injection and with gas injection with polarity reversal of the voltage source device.

1) When a normal injection of nitrogen is performed in a nitrogen environment, nitrogen is typically introduced into the electricity-depleting space when the temperature is expected to fall below the dew point.

Nitrogen gas is first introduced in the ionizer of the present invention. A typical jet flow rate is 7.1 liters/minute, and a maximum gas flow rate of 5.1m/s can be generated 1.25cm before the ionizer. This gas velocity is measured when the ionizer is off and does not include a gas flow driven by the corona discharge.

This experiment shows that nitrogen injection, whether surrounding a positive or negative voltage ionizer, increases the current. Whether or notThis phenomenon is found in the presence or absence of an external air flow in the dead space. The effect of this nitrogen gas with constant emission voltage is shown in table 1. In Table 1, the volume flow to the row of positive voltage ionizer pins (i.e., the collective name of all the pins on the same voltage ionizer pin, hereinafter also collectively referred to as the row of pins on the upper substrate 10 in FIG. 5) is designated as Q_aThe volume flow to the needle bank of the negative voltage ionizer (hereinafter, all the electrode needles on the lower substrate 10 in fig. 5 are also collectively referred to as the lower needle bank) is designated as Q_b. Note that: the voltage of the pin row of the positive voltage ion generator is different under the condition that external air flow exists and the external air flow does not exist.

Although a small amount of nitrogen gas was injected to the pin header of the positive voltage ionizer (Q for each ionizer)_a0.241 liters/minute), current enhancement in air is still achieved. When the air in the chamber was circulated, a higher nitrogen injection flow (2.41 liters/min per ionizer) was required to increase the current. This indicates that: the current enhancement is effected by gas in the vicinity of the ionizer.

Table 1: influence of Nitrogen gas injection on ion Current of ionizer

2) The air flow injection when the polarity of the voltage source device is reversed, namely: the voltage is not changed, but the connection of the positive pole and the negative pole of the voltage source device and the voltage connection ends of the two ionizers is reversed (if the voltage connection end of the ionizer originally constituting the upper part of the static eliminator is connected with the positive pole of the voltage source device, then it is connected with the negative pole of the voltage source device). During the test, each ionizer maintained a nitrogen gas injection flow of 7.11 liters/min. Referring to table 2, table 2 shows the case where only one fan circulates air. Although the polarity reversal of the voltage source device makes the positive polarity current to the lower ionizer larger, the upper ionizer can still control the ion balance at this time (which is a core indicator of the suppressor). This finding confirms that in the practical design of an ionizer, it is necessary to control the generation of carriers and the mixing of the ion gas flow. It is difficult to control the generation of positive or negative polarity carriers individually because of the electrode arrangement for the needles. However, ion balancing may be achieved under certain conditions by voltage regulation of the ionizer. The method is similar to the method of implementing a DC bias to the positive and negative electrodes to achieve ion balance.

Table 2: influence of polarity inversion of ionizer

The experimental procedure for charge decay in a nitrogen environment is as follows:

please refer to fig. 3, which is a graph illustrating a relationship between a charge decay time and an ion current of the positive and negative voltage ionizer. This test was performed under ion-equilibrium conditions, with a 20 second suspension test before and after the charge decay test. In these experiments, the upper ionizer was positive in polarity.

The ion balance condition is determined by grounded target or analog charged plate (CPM for short); and secondly by monitoring the voltage (as it floats, ungrounded, and then to steady state conditions). The CDT (charge-decay time, CDT for short) refers to the time required for the voltage of a suspended target (the capacitance is 85pF) or CPM to decrease from 1000V to 100V (both domestic and foreign technical standards are specified).

Charge decay may also be observed when the ionizer is off. When the temperature is higher than 330K (57 ℃) or higher, the index decreases as the temperature increases. Below 330K, a fixed decay time of approximately 1000s is its limit, depending on the leakage in the test system outside the dead space.

In general, the charge decay time is inversely proportional to the ion current of the ionizer, specifically referring to formula (2):

CDT＝α·I^—β(2)

in equation (2), CDT is the charge decay time, I is the ion current of the ionizer of opposite polarity opposite the charged plate (charged plate), and α is the regression constant.

Table 3 gives data on charge decay time versus emission current, air environment, which clearly gives information on the following four aspects: the charge decay in the positive and negative voltage polarities, the influence of temperature, the influence of nitrogen gas injection at the emitter, and the relationship between the charge decay and the emission current. Each data thus obtained is of great significance to the design of the ionizer for needle arrangement in the electrostatic eliminator of needle-pocket structure.

The data in table 3 show that the charge decay time is weakly dependent on the ion current. This reminds people to think: to extend the lifetime of an ionizer, one cannot rely on reducing the ion current to sacrifice the performance of the suppressor. However, if one wants to avoid spark discharge, then greater stability can only be achieved with higher ion emission currents.

When the ion current is stable, the charge decay time is reduced by increasing the temperature, largely due to the lower gas density at atmospheric pressure. Fan Law (Fan laus) states that: for ideal gas, the speed of gas blown downstream by a fan depends on the density of gas (V-rho)^-1/2) Of course, the gas density is inversely proportional to the absolute temperature (rho-T)^-1). Since the charge decay time appears to be driven by the flow of air from the 3 operating fans, the driving current to the target should follow V-T^1/2Under the ion balance condition, the ion current of the negative ion generator is-20 muA, and the relation between the charge decay time and the temperature has a correction coefficient which is as follows:

CDT₊(T)＝18.073—0.8242T^1/2the correction coefficient is 0.9911

CDT_-(T)＝18.106—0.8246T^1/2Correction coefficient is 0.9984

When the temperature is higher than the room temperature, 2 additional fans are operated to improve the gas circulation and to make the temperature distribution uniform. For the ion balance condition, the positive and negative polarity charge decay times will decrease when the fan is turned on. It appears that with increasing airflow rate, the delivered airflow dominates the ion transport, driving the charge towards the target simulating the CPM of the charged plate. Although the ion mobility is more temperature dependent than the gas density, the latter controls the charge decay. The charge decay time is independent of the voltage polarity revealing that: the gas flow has a great significance for transporting charge, but has little significance for carrier mobility.

Table 3: relation data of charge decay time, emission current and air environment

*N₂Nitrogen flow (Q) to the ionizer_z，Q_b) Liter/min. A fan: number of fans generating circulating air flow

Here, since the temperature in the physical formula is an absolute temperature, an absolute temperature scale is used in table 3, and the same is true for fig. 5 and 6.

Not only does the charge decay time decrease with increasing gas circulation, but the decay time is more strongly related to ion current. This is clearly seen by comparing the effect of the correction factors in table 3 on the operation of 1 and 3 fans. This effect is minimal at high temperatures.

Without air flow and nitrogen injection, the charge decay times at positive and negative polarity were 173 and 226 seconds, respectively. The ion current of the ionizer was-16.10 and + 15.15. mu.A, respectively. A nitrogen flow of 7.1 liters/minute (about 5m/s) on each side of the ionizer reduced the charge decay time to 30.2 and 35.2 seconds for both positive and negative polarities. The ion current was-17.35 and 16.45. mu.A. The nitrogen gas injection can improve the discharge environment and blow ions toward the target. As are ion nozzles and ion guns in practical applications. The injection of nitrogen gas into the region of the ionizer having a needle-hole structure will have an impact on the ion performance (especially when there is air flow in the dead space).

At low gas flow rates (3.7m/s), the ratio of the charge decay time with and without nitrogen injected against the ionizer was similar to the ratio of the carrier mobility in air (μ +/μ ═ 0.7). Negative charge carriers (free electrons) generated by corona discharge in nitrogen gas are attracted to oxygen atoms of the counter electrode. The charge decay time reached approximately 1 when the gas velocity increased to 8 m/s. This observation, combined with the findings of the voltage source device when the polarity is reversed, can prove that: at higher gas velocities and temperatures, gas flow-induced charge transport is predominant compared to ion transport. The temperature is lowered substantially by evaporation of nitrogen, i.e. liquid nitrogen. Gasified nitrogen is also introduced into the electricity-eliminating space in advance, and the refrigeration of the space can eliminate dew condensation and icing. Generally, the dead space is maintained at a positive pressure during nitrogen cooling (e.g., a small door is designed to be opened periodically to allow removal or insertion of test devices during testing of the dead space). In this operation air is brought into the electricity-depleting space. The dominant effect of free electrons in nitrogen occurs when less than 1% of the oxygen is in the dead space.

Please refer to fig. 6, which is a schematic diagram of a charge decay curve obtained by using the ionizer of this invention. As shown in FIG. 6, the abscissa represents temperature, and the ordinate represents the ratio CDT of the decay time of the charges when the positive and negative voltage ionizers emit ions₊/CDT_-When the residual voltage is lower than-20V, the total emission current is about 20 muA, the ion current of the negative voltage ionizer is-20 muA, CDT₊/CDT_-The gradual decrease in temperature is accompanied by an imbalance of ions at low temperatures.

Please refer to fig. 7, which is a schematic diagram of a charge decay time curve obtained by using the ionizer of this invention. As shown in FIG. 7, the charge decay time as a function of temperature was 20 μ A per pin row and-20 μ A for negative voltage ionizer, and the 20 second levitation test was completed many times, even at the lowest temperature, where the typical residual voltage was maintained within-20V around 0. The test shows that: the charge decay time decreases with increasing current.

Based on the data in fig. 7, it is shown that the ion current (i.e., free electron current, also called negative charge carriers) of a negative voltage ionizer is the dominant current driven by the voltage source, and is the basic reading of the positive and negative ion current readings. The contribution of free electron carriers at low temperatures is also dominant and it can be concluded that it is also a better contribution than gas flow at elevated temperatures. However, the charge decay time observed at higher temperatures also corresponded to the charge decay time at lower positive target voltages, indicating that the number of negative charge carriers reaching the positive target corresponded to the following two cases (i.e., low temperature nitrogen and high temperature air). The number of carriers reaching the negative pressure target is about one third of this number. The ionizer continuously generates a concentration of positive ions (i.e., positive charge carriers) that is greater than the concentration of free electrons (i.e., negative charge carriers) and increases as the temperature decreases. However, this positive ion concentration is much less than that produced at room temperature and during temperature ramping. The graph in fig. 7 shows that 90% of the positive ion current is "pinched off" when the environment is switched from air to nitrogen. The measured ion current of a positive voltage ionizer is clearly overwhelmed by the free electron current and it is not controllable to maintain the production of positive ions. Then, to achieve ion balance in a variable ion mobility environment, the blocking of the ionizer is a necessary step.

In summary, in the ionizer and the static eliminator provided by the present invention, the static eliminator includes a voltage source device and two ionizers respectively connected to the voltage source device, the two ionizers are oppositely disposed, and the electrode pins on the two ionizers are parallel to each other and the tips of the electrode pins face the same direction; the ion generator comprises a substrate and at least one electrode needle fixed on the substrate, at least one accommodating hole is formed in the substrate, and each accommodating hole accommodates one electrode needle; the tail end of each electrode needle is fixed on the substrate in the accommodating cavity, and the tip end of each electrode needle extends out of the accommodating cavity and is higher than the surface of the substrate. The static eliminator formed by the ionizer with the needle-hole structure (namely, the electrode needle is accommodated in the accommodating hole) is more easily used for transmitting airflow and ion flow based on the gap between the electrode needle and the accommodating hole in the needle-hole structure, so that the corona discharge can be stably generated in a nitrogen environment.

On the other hand, based on the airflow port on the ionizer, blowing of clean dry air or nitrogen can be realized, and the airflow is distributed in a forced ventilation mode, so that the gas in the electrostatic eliminator flows, and the transmission of charge carriers is enhanced.

On the other hand, the length extension direction of each ion generator is inclined downwards by 17-20 degrees relative to the horizontal direction, so that the flowing direction of gas and the flowing direction of transferred charge carriers can be effectively guided to face a charge elimination object, and the charge elimination efficiency is improved.

The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.

Claims (10)

1. An ionizer, comprising: the electrode needle holder comprises a base body and at least one electrode needle fixed on the base body, wherein at least one accommodating hole is formed in the base body, and each accommodating hole accommodates one electrode needle; the tail end of each electrode needle is fixed on a base body in an accommodating hole, and the tip end of each electrode needle extends out of the accommodating hole and is higher than the surface of the base body.

2. The ionizer of claim 1 further comprising a voltage source connecting terminal provided at one side of said base body, said voltage source connecting terminal being connected to the rear ends of all the electrode pins through a lead wire.

3. The ionizer of claim 2 further comprising an airflow port disposed on one side of said base, said airflow port communicating with said receiving cavity, said airflow port and said voltage source connection terminal being symmetrically disposed with respect to said base.

4. The ionizer of claim 1 or 3 in which the receiving cavity is funnel shaped.

5. The ionizer of claim 1 wherein all of the electrode pins are parallel to each other and perpendicular to the surface of the substrate, all of the electrode pins being tungsten pins.

6. The ionizer of claim 5 wherein said electrode pins have a diameter ranging from 0.20mm to 0.30mm and a spacing between two adjacent electrode pins ranges from 57mm to 58 mm.

7. A static eliminator adapted for static elimination in a nitrogen environment, comprising: a voltage source device and two ionizers according to any one of claims 1-6 respectively connected to the voltage source device, wherein the two ionizers are oppositely arranged, and the electrode pins on the two ionizers are parallel to each other and the tips of the electrode pins face the same direction.

8. The static eliminator according to claim 7, wherein the length extension direction of each ionizer is downwardly inclined at an angle ranging from 17 ° to 20 ° with respect to the horizontal direction.

9. The static eliminator according to claim 7, wherein the voltage source connection terminals of two ionizers are located on the same side, and the voltage source connection terminal of one ionizer is connected to the positive electrode of said voltage source means to constitute a positive voltage ionizer; and the voltage source connecting terminal of the other ionizer is connected with the negative electrode of the voltage source device to form a negative voltage ionizer.

10. A static eliminator according to claim 9, wherein the spacing between said two ionizers is in the range of 28mm to 29 mm.

Images