EP4179340A1

EP4179340A1 - Device for determining the electrical resistance of a system, and associated method

Info

Publication number: EP4179340A1
Application number: EP21739086.3A
Authority: EP
Inventors: Roger Morin; Alain Degiovanni; Laurent LAPENA; Evelyne SALANCON
Original assignee: Aix Marseille Universite; Centre National de la Recherche Scientifique CNRS
Current assignee: Aix Marseille Universite; Centre National de la Recherche Scientifique CNRS
Priority date: 2020-07-10
Filing date: 2021-06-30
Publication date: 2023-05-17
Also published as: US20230251293A1; FR3112393A1; FR3112393B1; WO2022008325A1

Abstract

The invention relates to a device (1) for determining the electrical resistance of a system (S), the device comprising: - a field effect electron emitter (10) suitable for emitting electrons when the electrical emission potential Ve of the electron emitter is higher than a threshold value VL, the emitting end of the emitter being at least partially conductive; - a piece of equipment (20) capable of determining the electrical emission potential Ve of the electron emitter; - a voltage source (40) designed to apply a potential difference E to the device (1) and generate an electric field at the emitter (10); - an electron detector (80) capable of detecting all or some of the electrons emitted by the electron emitter so as to measure the intensity of the current Imes flowing between the emitter and the detector; - electrical connection means (91, 92) designed to electrically connect the system (S) and the device (1) in such a way that the current intensity flowing between the emitter and the detector can also pass through the system.

Description

Title of the invention: Device for determining the electrical resistance of a system and associated method

Technical field of the invention

The invention lies in the field of the measurement of electrical variables, more specifically the measurement of electrical resistance.

The invention is particularly aimed at determining very high electrical resistance values.

State of the art

The measurement of very large values of electrical resistance is a key element in the manufacture of very high impedance voltmeters or very low current ammeters, as well as in the characterization of electrical insulating materials and associated devices.

A known principle for measuring a high electrical resistance value of a system consists of applying a high voltage to the system whose resistance is to be measured and using a Hall effect current sensor, such as a amperometric probe or clamp, to measure the intensity and deduce the resistance. However, the devices implementing this principle do not make it possible to measure resistance values greater than 10 ¹⁰ or 10 ¹¹ Ohms and certain electrical insulators cannot therefore be characterized.

There is also a device of the electrometer type, making it possible to carry out resistance measurements up to 200 Tera Ohms (200 TW), that is to say 2.10 ¹⁴ Ohms. This is generally used for electrical insulation measurements. In this type of device, the measurement of very high resistances is directly linked to the use of a stable source of very low current. A known electrometer from the company Keithley® makes it possible to measure lfA (10 ¹⁴ A) with a sensitivity of lfA (10 ¹⁵ A).

However, a device is sought which makes it possible to determine resistance values beyond 200 TW, which can reach 10 ²² W. However, the limitation of the measurement of a large resistance value is limited by the thermal noise, even for a device of the electrometer type as described previously.

The invention aims to overcome the aforementioned drawbacks of the prior art.

More particularly, it aims to produce a device making it possible to measure the resistance of a system having a very high value of electrical resistance, beyond the Tera Ohm, or even beyond 10 ¹⁵ Ohms and possibly reaching 10 ²² Ohms.

Disclosure of invention

A first object of the invention making it possible to remedy these drawbacks is a device for determining the electrical resistance of a system, the device comprising:

- a field effect electron emitter capable of emitting electrons (thus generating a current) when the electric emission potential V _e of the electron emitter is greater than a threshold value V _L ;

- equipment capable of determining the electric emission potential V _e of the electron emitter;

- A voltage source suitable for applying a potential difference E to the device and generating an electric field at the emitter; - an electron detector capable of detecting all or part of the electrons emitted by the electron emitter so as to measure the intensity of the current I _mes flowing between the emitter and the detector, and

- electrical connection means suitable for electrically connecting the system whose electrical resistance is to be determined and the device, so that the current flowing between the emitter and the detector can also pass through said system.

According to the present invention, the electric emission potential can be abbreviated as “emission potential”.

Generally, in the present invention, the term “potential” designates an electric potential.

The term "system" in the present invention designates any component, object, device, having electrical connection terminals of the dipole type, and having an electrical resistance of very high value.

A field emission (or cold emission) electron emitter is a source of electrons which comprises an emitter material whose geometry or conformation makes it possible to achieve a large electric field when subjected to an electric potential. Under the effect of such an electric field, electrons tunnel through a potential barrier from the Fermi level, at room temperature, and are emitted by the material. The application of the electric field to the material can be combined with the heating of the material, in order to obtain a Schottky emission, which makes it possible to reduce the electric potential of extraction of the electrons.

The end of the emitting material must be at least partially conductive.

The transmitter material generally comprises a conductive wire (metal or semi-conductor) one end of which is sharpened. The most common material is tungsten.

The emitter material forms a cathode (generally referred to as a "cold cathode").

To extract the electrons from the emitter, the device comprises an electron extractor, the extractor being placed between the emitter and the detector. The electron extractor generally comprises an extraction electrode, forming an anode, configured to generate an electric field when an electric extraction potential is applied to it. Thus, the electrons are emitted towards said electrode, and are directed towards the detector. The emitter is negatively biased with respect to the extractor. For example, the emitter is biased negative with respect to the extraction electrode which is grounded.

Alternatively to an electrode, the extractor can comprise an extraction grid forming an anode.

By grid is meant an electrode having one or more openings for the passage of electrons.

According to one embodiment, the equipment able to determine the electric emission potential V _e of the electron emitter comprises an energy analyzer.

According to one embodiment, the equipment capable of determining the electric emission potential V _e of the electron emitter comprises:

- a delay grid arranged between the emitter and the detector, in particular between the extractor and the detector, and - A delay voltage source connected to the delay gate, and capable of applying to said delay gate a delay potential N making it possible to delay and stop the electrons arriving at the detector.

The electron detector generally makes it possible to count all or part of the electrons emitted. Thus, a means for counting electrons is generally associated with the detector or included in the detector.

According to one embodiment, the detector comprises an electron multiplier, for example a channeltron or even a microchannel plate.

Preferably, the device comprises a vacuum chamber, preferably at ultra-high vacuum (that is to say between 10 ⁶ and 10 ⁹ Pa), the vacuum chamber being capable of receiving at least the electron emitter , all or part of the equipment for determining the electric emission potential, all or part of the electron detector, and possibly all or part of the electron extractor. This can be a conventional vacuum chamber (in which the vacuum is formed by a vacuum pump, or even an ultra-high vacuum) or a sealed enclosure containing a getter or getter.

Preferably, the device further comprises at least one sealed electrical bushing, said electrical bushing being adapted to electrically connect the interior and exterior of the vacuum chamber in a sealed manner, and being electrically insulated, typically corresponding to a higher resistivity or equal to 10 ¹⁸ Q.cm. This can typically be a sapphire via.

The electrical feedthrough makes it possible to pass in particular electrical connections between the system to be measured which is not arranged in the vacuum chamber and the elements arranged in the vacuum chamber, and more generally between the elements arranged in the vacuum chamber. vacuum and the elements outside the vacuum chamber.

At least one electrical connection means suitable for electrically connecting the system and the vacuum chamber passes through said sealed bushing.

In the case of high resistances, the resistance measurements can be falsified by the circulation of leakage currents which travel on the surface of the system to be measured, for example through humidity and/or surface contaminants whose resistance is less important than that of the system. In order to eliminate leakage currents, the measuring device comprises a guard able to contain the system to be measured and/or to be connected to the system to be measured. A guard is defined as a means of protection configured to reduce the leakage current and/or distribute the potential around the system to be measured. The guard can be electrically connected to the detector, so as to allow a differential measurement.

A second object of the invention is a method for determining the resistance of a system implementing the device according to the invention, the method comprising the following steps:

- a step of connecting the system to the electrical connection means of the device;

- an electron emission step for a potential difference value E applied to the device;

- a step of measuring the current intensity I _e flowing through the system, for the potential difference value E, said measurement step comprising measuring the intensity of the current I _mes flowing between the emitter and the detector when the emitted electrons are not slowed down before reaching the detector, so that the current I _mes measured by the detector corresponds to the current I _e flowing through the system;

- a step of determining the electrical emission potential V _e of the electron emitter for the potential difference value E;

- a step for calculating the resistance Rs of the system to be measured given by the equation

It is specified that the emission of electrons is carried out by the electron emitter, that the measurement of the intensity of the current circulating between the emitter and the detector is permitted by the detector, and that the determination of the electric potential emission is allowed by the equipment capable of determining the electric emission potential of the electron emitter.

According to one embodiment, the step of determining the electric emission potential V _e of the emitter comprises:

- a step of applying to the equipment a limit delay potential value N _L sufficient to stop the electrons arriving at the detector, so that the intensity measured I _mes at the level of the detector decreases to a value I ₀ (Io corresponding to the detection limit),

- the electrical emission potential V _e sought being equal to the value of the limit retarding potential NL; the step of measuring the intensity of the current I _e being carried out for a zero delay potential N.

This embodiment is suitable for a device whose equipment capable of determining the electrical emission potential V _e of the electron emitter comprises a delay grid arranged between the emitter and the detector, in particular between the extractor and the detector, and a delay voltage source connected to the delay gate, and capable of applying to said delay gate a delay potential N making it possible to delay and stop the electrons arriving at the detector.

Brief description of figures

Other characteristics and advantages of the invention will become apparent with the aid of the description which follows, given by way of illustration and not limitation, given with regard to the appended figure:

[Fig.l] represents an example of a device for determining the electrical resistance according to the invention.

Detailed description of the invention

Measuring device

FIG. 1 represents an example of a device for determining the electrical resistance according to the invention.

The device represented comprises:

- A field effect electron emitter 10 capable of emitting a current of electrons when the electric potential V _e of the electron emitter is greater than a threshold value V _L ;

- Equipment 20 capable of determining the electric potential V _e of the electron emitter;

- an electron extractor 30; - A voltage source 40 suitable for applying a potential difference E to the device and generating an electric field at the emitter 10;

- an electron detector 80 capable of detecting all or part of the electrons emitted by the electron emitter and associated with (or comprising) an electron counter 81 so as to measure the intensity of the current I _mes flowing between the emitter and detector;

- a vacuum chamber 50 capable of receiving at least the electron emitter 10, all or part of the equipment 20, the electron extractor 30 and the electron detector 80;

- A guard 70 adapted to receive the system S to be measured: the guard shown is electrically connected to the detector 80 and therefore to the counter 81, thus making it possible to carry out a differential measurement;

- an electrical crossing 60 suitable for sealingly connecting the interior and exterior of the vacuum chamber 50.

In addition, the system S whose electrical resistance Rs is to be determined and which is placed outside the vacuum chamber in the ambient environment, is electrically connected to the device by a first electrical connection 91 between a terminal of the system S and the electron emitter 10, and a second electrical connection 92 between another terminal of the system S and the detector 80. Thus, the current flowing between the emitter and the detector can also pass through said system. The electrical connections may conventionally be cables and/or electrical connections. The first electrical connection can pass through the electrical bushing 60.

The end of the emitter 10 must be at least partially conductive.

The flow of electrons has a kinetic energy eV _e , where e is the charge of the electron.

The voltage source 40 must be stable, preferably have a stability of 10 ³ (1 V for 1000V).

A field emission (or cold emission) electron emitter is a source of electrons which comprises an emitter material whose geometry or conformation makes it possible to reach a large electric field when it is subjected to an electric potential, the electric field being of the order of 1 V/mm. Under the effect of such an electric field, electrons tunnel through a potential barrier from the Fermi level, at room temperature, and are emitted by the material. The application of the electric field to the material can be combined with the heating of the material, in order to obtain a Schottky emission, which makes it possible to reduce the electric potential of extraction of the electrons.

Alternatively, the emitter material may comprise a conductive wire (for example a carbon wire) one end of which is cut into a point and a crystal made of an insulating material, for example celadonite, halloysite, hematite, deposited on the conductive point (without the completely cover so that the tip is at least partially conductive). The diameter of the tip can be 10 μm, or even a few μm. The dimensions of the crystal can be of the order of a μm and its thickness of about ten nanometers, for example 50 nm. Still alternatively, the emitter material may comprise a conductive wire, one end of which is cut into a point, and the point machined to form a plate. A crystal made of an insulating material is placed on the plate (without covering it entirely so that the tip is at least partially conductive). The plate may have a diameter of between 5 and 50 μm or even a hundred μm. The crystal made of an insulating material may have a width (and/or length) of less than 100 nm, preferably between 10 and 100 nm, for example 50 nm, and a thickness less than or equal to 50 nm, preferably between 1 and 50 nm, for example 10 nm. The plate can have a roughness, comparable to the thickness of the crystal, so that the simple deposition of the crystal on the plate, combined with the roughness of the latter makes it possible to form a conductive / vacuum / insulating assembly, in which the vacuum is formed by the spaces between the asperities of the plate (conductor) and the crystal (insulator).

The electron extractor 30 is adapted to extract the electrons from the emitter towards the detector. The extractor is illustrated in the form of an extraction grid 31 forming an anode, and configured to generate an electric field when an electric extraction potential is applied to it. Thus the electrons are emitted towards said extraction grid and towards the detector. The emitter is negatively biased with respect to the extractor and the extraction electrode is grounded T.

Equipment 20 shown includes:

- a delay grid 21 arranged between the emitter 10 and the detector 80, and more precisely between the extraction grid 31 and the detector 80;

- a delay voltage source 22 connected to the delay gate, and capable of applying to said delay gate a delay potential N making it possible to delay and stop the electrons arriving at the detector.

The delay voltage source 22 must be stable, preferably have a stability of 10 ³ (IV for 1000V).

The equipment can comprise one or more delay grids arranged one after the other on the path of the electrons coming from the emitter, said delay grids being arranged between the emitter 10 and the detector 80, each delay grid being connected to its own voltage source, to allow the energy analysis of the electrons, until the emission of secondary electrons at the output of the series of delay gates is suppressed.

The delay grid(s) and delay voltage source(s) can form a delay field electron energy analyzer.

Alternatively, another type of energy analyzer with retarding field (“Retarding field energy analyzer” or “RFEA” in English) can be implemented.

Still alternatively, another energy analyzer can be implemented. For example, it can be a hemispherical sector analyzer (HSA).

The electron detector 80 generally makes it possible to count all or part of the electrons emitted. Thus, a means 81 for counting electrons is generally associated with the detector or included in the detector. The electron detector 80 may consist of (or include) an electron multiplier.

An electron multiplier can be formed by placing a perforated or porous plate, such as a lead glass plate, between an input electrode and an output electrode, and providing a DC electric field between the electrodes. When incident electrons strike the entrance electrode and collide with surfaces inside the plate, electrons, sometimes called "secondary electrons", are produced. Secondary electrons are accelerated by the electric field towards the exit electrode and collide with other surfaces inside the plate to produce more secondary electrons, which can in turn produce more electrons when they accelerate through the plate. As a result, a cascade of electrons can be produced as secondary electrons accelerate through the plate and collide with more surfaces, with each collision possibly increasing the number of secondary electrons. A relatively strong electronic pulse can be detected at the output electrode.

The electron detector 80 can be a microchannel plate (known under the term “MCP” for “MicroChannel Plate”), or a double microchannel plate.

A microchannel plate is an electrical charge amplifier device comprising a network of microchannels, for example cylindrical and hollow microchannels. Each microchannel, which can act as an independent electron multiplier, has an inner wall surface formed by a conductive and electron-emitting layer. The plate is biased by a bias voltage. When incident electrons enter a microchannel, they collide with the surface of the wall and cause the emission of several secondary electrons which are accelerated by the bias voltage. The emitted electrons will in turn strike the wall and cause the emission of other electrons, there is therefore cascade amplification.

The electron detector 80 can be a microsphere plate (known by the term “MSP” for “MicroSphere Plate”), or a double microsphere plate.

A microsphere plate is an electrical charge amplifier device comprising a plate formed of microscopic spheres which have conductive and electron-emitting surfaces. The spheres are assembled and bonded together, for example, by compression and sintering. The plate is biased by a bias voltage. When incident electrons collide with the surfaces of the spheres, they cause the emission of several secondary electrons which are accelerated by the bias voltage across the interstices defined by the spheres. The emitted electrons will in turn hit other spheres and cause the emission of other electrons, so there is cascade amplification.

Alternatively, the detector can be a discrete dynode electron multiplier.

Preferably, the detector is a tubular electron multiplier or “channeltron”, sometimes called in English “Channel PhotoMultiplier” or “CPM”.

The detector is associated with (or comprises) a counting device, for example counting electronics 81. Electronic counting of electrons, for example at the output of a channeltron, is electronics known to those skilled in the art, which generally allows signal discrimination and which provides a 0-1 (TTL) signal at the output to be able to count the hits.

The vacuum chamber 50 is preferably an ultra-high vacuum chamber (that is to say between 10 ⁶ and 10 ⁹ Pa), capable of receiving at least the electron emitter 10, the delay grid 21, the extraction grid 31 and the electron detector 80.

The counting electronics 81 is generally placed outside the vacuum chamber.

The vacuum chamber can be constructed from standard ultra-high vacuum metal components, connected to a high vacuum pump (with metal gaskets to ensure tightness).

Alternatively, the vacuum chamber can be formed by a sealed enclosure (for example a glass tube) containing a getter pump or “gas trap”. It is recalled that a getter pump is a fixed pump in which the gas contained in the enclosure is mainly fixed by chemical combination with a getter, making it possible to form a vacuum in said enclosure. The getter is usually a metal or metal alloy in solid form or deposited in thin layers.

The electrical crossing 60 makes it possible to connect the inside and the outside of the vacuum chamber in a sealed manner. The bushing is electrically insulated to prevent leakage currents. Preferably, the resistivity of the bushing at 300K is at least 10 ¹⁸ W.ah. It may be a bushing with an alumina ceramic insulator (sapphire), or other bushings known in the field of ultra-high vacuum. The first electrical connection 91 passes through said sealed electrical bushing.

Other electrical crossings may be provided, in particular to connect the delay gate 21 and the delay voltage source 22 in a sealed manner, as well as the extraction gate 31 and the ground T, or even the detector 80 to the counting means 81 , also to pass the second electrical connection 92.

An electrical bushing makes it possible in particular to electrically connect the system to be measured which is not placed in the vacuum chamber and the elements placed in the vacuum chamber.

In the case of high resistances, the resistance measurements can be falsified by the circulation of leakage currents which travel to the surface of the system to be measured through humidity and/or surface contaminants whose resistance is lower than that of the system. In order to eliminate leakage currents, the measuring device may comprise a guard 70 able to contain the system to be measured and/or to be connected to the system to be measured. The guard forms a connection terminal. It is configured to reduce the leakage current and/or distribute the potential around the system to be measured. The guard may be formed by an electrically conductive cage (of the Faraday cage type) capable of containing the system and connected to a guard electrode, the whole being electrically connected to the detector. The guard can be formed by any other means making it possible to connect the system to be measured to a differential system.

Method for determining the resistance of the system A description will now be given of a method for measuring the resistance of a system which can be implemented in particular with the measuring device of FIG. 1, and more generally with a measuring device according to the invention.

The measurement method consists of emitting electrons and determining the electric emission potential V _e of the electron emitter. The electrons are emitted for a potential difference value E making it possible to generate an electric field at the level of the electron emitter. The potential difference value E must be sufficient to obtain a significant electron counting rate and to generate a current whose intensity I _me s can be measured at the level of the detector. When the circuit between the device and the system to be measured S is closed, and the electrons are not delayed between the emitter and the detector, the current I _mes measured at the level of the detector is also the current I _e which crosses the system S. Current measurement I _{mes is} used to calculate the value of the electrical resistance of the system (S).

Initially the lag potential N is set to 0 volts.

The gain of the detector and the electronic counting range are adjusted in order to be able to measure the lowest possible current intensity by counting.

The potential difference is increased to the value E which makes it possible to obtain a significant counting rate and therefore a significant current intensity measured I _mes .

A first step consists in measuring the intensity of the current I _mes thanks to the electron detector 80 associated with the counting electronics 81, for this potential difference E and this, with a delay potential N of zero.

In this case, the electrons are not delayed and even less stopped and the current I _e passing through the system is equal to the measured current I _me s at the level of the detector.

To measure the emission potential V _e , the second step consists in applying to the equipment 20 ( _{delay grid 21 illustrated in FIG. 1) a sufficient delay potential N L} (limit delay potential) to delay the electrons until they stop .

On the device illustrated in FIG. 1, the delay potential N is varied by means of the delay voltage source 22 so that the electrons are slowed down and then stopped. Thus, a decreasing flux of electrons reaches the detector 80 and the measured intensity I _me s at the level of the detector decreases to a value I ₀ , Io corresponding to the detection limit, for N equal to NL. At this _{delay potential value N L} , the counting electronics 81 no longer count any electrons.

This value N _L of the retarding potential measures the kinetic energy divided by the charge of the electron for the electrons emitted by the field emitter, and is therefore equal to the sought emission potential Ve-

The resistance Rs of the system to be measured is equal to the voltage V _s at the terminals of the system divided by the intensity of the current I _e which crosses it.

The resistance Rs of the system to be measured S is therefore given by the equation:

Math.1 Determined resistance range

Depending on the electron detector used, the electron count rate at room temperature is between 1 c/s and 10 ⁸ c/s, ie between about 10 ¹⁹ and 10 ¹¹ A. For such current values, the inventors have determined that a typical value of the emission potentials V _e for a field emitter is between 10 and 1000V.

The equation Math.l shows that the determination of the resistance of the system Rs requires determining (E - V _e ). This means that E must be significantly distinct from V _e . For example E can be substantially equal to twice V _e so that (E - V _e ) is of the order of V _e , ie between 10 and 1000 V. With such a base, the measurement range of the resistance Rs lies between 10 V/10 ¹¹ A and 1000V/10 ¹⁹ A, that is to say between 10 ¹² and 10 ²² Ohms depending on the electron detector, the field emitter and the electronics used.

The relative uncertainty on the measured resistance Rs is linked to the relative uncertainty on E, V _e , E - V _e and that on I _e . The measurement of (E - V _e ) can critically depend on the measurement of the limit retarding potential NL, which determines V _e . Measurement accuracy can be improved by using one or more of the following methods:

- increase the stability of the voltage sources E and N;

- limit the divergence of the electron emission beam;

- bring the emitter and the detector as close as possible in order to be able to detect the most electrons emitted (and improve the accuracy of measurement of the current intensity at the level of the detector);

- limit the geometric imperfections of the delay grid;

- take into account the detection efficiency of the detector;

- use a very high impedance crossing (for example in sapphire whose resistivity is greater than or equal to 10 ¹⁸ Ohm);

- use a protective structure for the system to be measured (guard) adapted to limit or even eliminate the leakage current.

Unless otherwise indicated, the different modes, examples and variants presented can be combined with each other.

Furthermore, the present invention is not limited to the embodiments described above but extends to any embodiment falling within the scope of the claims.

The invention may in particular find applications in:

- the characterization of insulating materials;

- measurement of large electrical resistance values;

- the manufacture of voltmeters for very high impedance;

- the manufacture of ammeters for very low current.

Claims

1. Device (1) for determining the electrical resistance of a system (S), said device comprising:

- an electron emitter (10) by field effect capable of emitting electrons when the electric emission potential V _e of the electron emitter is greater than a threshold value VL, the emitting end of said emitter being at less partially conductive;

- equipment (20) capable of determining the electric emission potential V _e of the electron emitter;

- a voltage source (40) suitable for applying to the device (1) a potential difference E and generating an electric field at the emitter (10);

- an electron detector (80) capable of detecting all or part of the electrons emitted by the electron emitter so as to measure the intensity of the current I _mes flowing between the emitter and the detector;

- electrical connection means (91, 92) adapted to electrically connect the system (S) and the device (1) in such a way that the current flowing between the emitter and the detector can also pass through said system.

A device (1) according to claim 1, further comprising an electron extractor (30) configured to extract electrons from the emitter (10) to the electron detector (80), the extractor being disposed between emitter and detector.

3. Device (1) according to claim 2, the electron extractor comprising an extraction electrode or an extraction grid (31) arranged between the emitter (10) and the detector (80) and configured to generate an electric field when an electric extraction potential is applied to it.

4. Device (1) according to claim 3, the extraction electrode or the extraction grid (31) being connected to a ground terminal (T).

5. Device (1) according to any one of the preceding claims, the equipment (20) comprising an electron energy analyzer.

6. Device (1) according to any one of the preceding claims, the equipment (20) comprising:

- a delay grid (21) arranged between the emitter (10) and the detector (80) and

- a delay voltage source (22) connected to said delay gate, and able to apply to said delay gate a delay potential N making it possible to delay and stop the electrons arriving at the detector (80).

7. Device (1) according to any one of the preceding claims, the detector (80) comprising an electron multiplier, for example a channeltron, or even a microchannel plate.

8. Device (1) according to any one of the preceding claims, further comprising an electron counting means (81) associated with, or included in, the detector (80).

9. Device (1) according to any one of the preceding claims, further comprising a vacuum chamber (50) capable of receiving at least the electron emitter (10), all or part equipment (20), all or part of the electron detector (80), and possibly all or part of the electron extractor (30).

10. Device (1) according to claim 9, further comprising a sealed bushing (60), said electrical bushing being adapted to electrically connect in a sealed manner the interior and the exterior of the vacuum chamber (50) and being insulated electrically, at least one electrical connection means (91) passing through said sealed bushing.

11. Device (1) according to any one of the preceding claims, further comprising a guard (70), the system to be measured (S) being connected to, and/or disposed in, said guard, the guard being configured to reduce the leakage current and/or distribute the potential around the system to be measured, the guard being able to be electrically connected to the detector so as to allow a differential measurement.

12. Method for determining the resistance of a system (S) implementing the device according to one of claims 1 to 11, the method comprising the following steps:

- a step of connecting the system (S) to the electrical connection means (91, 92) of the device;

- an electron emission step for a potential difference value E applied to the terminals of the device;

- a step for measuring the current intensity I _e flowing through the system (S), for the potential difference value E, said measurement step comprising measuring the intensity of the current I _mes flowing between the emitter and the detector when the emitted electrons are not slowed down before reaching the detector, so that the measured current I _mes corresponds to the current I _e passing through the system;

- a step of determining the electric emission potential V _e of the electrons emitted for the potential difference value E;

- a step for calculating the resistance Rs of the system to be measured (S) given by the equation

13. Determination method according to claim 12, implementing the device according to claim 6 or one of claims 7 to 11 in combination with claim 6, the step of determining the emission voltage V _e comprising:

- a step of applying to the equipment (20) a delay potential value N _L sufficient to stop the electrons arriving at the detector, so that the measured intensity I _mes at the level of the detector (80) decreases to 'to a value I ₀ , corresponding to the detection limit of the detector,

the desired emission electric potential V _e being equal to the limit retarding potential value N _L ; the step of measuring the current I _e being carried out for a zero delay potential N.