Electric current measurement apparatus, voltage measurement apparatus and power supply apparatus

An electric current measurement apparatus for measuring an electric current of each electrode of an electron tube includes a transformer, a detection resistor connected in an ampere meter route for measurement, a voltage detection unit for detecting electric potential difference of the detection resistor and outputting pulse signals corresponding to the detected electric potential difference, a switching part for providing a short circuit of the secondary winding according to the pulse signals, and a measurement current value output unit. The measurement current value output unit measures pulse attribute of pulse-shape signals which are induced on the primary winding of the transformer caused by the short circuit of the secondary winding, and outputs a value of electric current flowing through the detection resistor with referring to a predetermined relationship between a value of the electric current flowing through the detection resistor and the pulse signals generated in the voltage detection unit.

This application is based upon and claims the benefit of priority from Japanese patent application No. 2008-071560, filed on Mar. 19, 2008 the disclosure of which is incorporated herein in its entirety by reference.

TECHNICAL FIELD

The present invention relates to an electric current measurement apparatus suitable for measuring an electric current which flows to an electrode of an electron tube, a voltage measurement apparatus suitable for measuring the voltage applied on an electrode of an electron tube and a power supply apparatus equipped with those apparatus.

BACKGROUND ART

A traveling wave tube and klystron or the like are electron tubes which oscillate or amplify a high-frequency signal (microwaves) by interacting an electron beam ejected from an electron gun with the high-frequency signal. A composition example of the traveling wave tube1is illustrated inFIG. 9. The traveling wave tube includes an electron gun10, a spiral-shape helix electrode20, a collector electrode30and an anode electrode40. The electron gun10ejects an electron beam50. The helix electrode20is a high-frequency circuit which interacts the electron beam50ejected from the electron gun10with the high-frequency signal (microwaves). The collector electrode30captures the electron beam50outputted through the helix electrode20. The anode electrode40draws out electrons from the electron gun10and leads the electron beam50ejected from the electron gun10into space surrounded by the helix electrode20. The electron gun10includes a cathode electrode11which ejects thermal electrons and a heater12which gives thermal energy for ejecting thermal electrons to the cathode electrode11.

The electron beam50ejected from the electron gun10is accelerated by electric potential difference between the cathode electrode11and the helix electrode20, and is introduced into space surrounded by the helix electrode20. The electron beam50travels through the space surrounded by the helix electrode20interacting with the high-frequency signal inputted from one end of the helix electrode20. The electron beam50which has passed through the space surrounded by the helix electrode20is captured in the collector electrode30. At that time, the high-frequency signal amplified by the interaction with the electron beam50is outputted from other end of the helix electrode20.

A power supply apparatus60includes a helix power supply61, a collector power supply62and a heater power supply63. The helix power supply61supplies helix voltage (Ehel) between the helix electrode and the cathode electrode11. The helix voltage (Ehel) supplied on the cathode electrode11is a negative DC (direct-current) voltage based on the electric potential of the helix electrode20(HELIX). The collector power supply62supplies the collector voltage (Ecol) between the collector electrode and the cathode electrode11. The collector voltage (Ecol) supplied on the collector electrode30is a positive DC voltage based on the electric potential of the cathode electrode11(H/K). The heater power supply63supplies the heater voltage (Eh) between the cathode electrode11(H/K) and the heater12. The heater voltage (Eh) supplied on the heater12is a negative DC voltage based on the electric potential of the cathode electrode11(H/K). The helix electrode20is usually connected to a case of the traveling wave tube1and grounded in the power supply apparatus60.

Further, althoughFIG. 9shows an exemplary configuration of the traveling wave tube1equipped with only one collector electrode30, the traveling wave tube may also have a configuration in which a plurality of collector electrodes are provided. InFIG. 9, although a configuration in which the anode electrode40is connected with the helix electrode20in the power supply apparatus60is shown, the traveling wave tube may also have a configuration in which an anode voltage (Ea) is supplied between the cathode electrode11(H/K) and the anode electrode40, and the anode voltage (Ea) is a positive DC voltage based on the electric potential of the cathode electrode11(H/K).

The helix voltage (Ehel), the collector voltage (Ecol) and the heater voltage (Eh) are generated by using the power supply apparatus which includes an inverter, a transformer and a rectifier circuit. The inverter converts a DC voltage supplied from outside into an AC (alternating current) voltage and supplies the converted AC voltage on a primary winding of the transformer as an output. The transformer performs voltage conversion of the AC voltage inputted to the primary winding, and outputs the AC voltage converted into a desired voltage from a secondary winding. The rectifier circuit converts the AC voltage outputted from the secondary winding of the transformer into the DC voltage which has a desired voltage value. Therefore, the power supply apparatus is provided for outputting the DC voltage having a desired voltage value necessary for each of the helix voltage (Ehel), the collector voltage (Ecol) and the heater voltage (Eh).

As a method for measuring an electric current which flows to the cathode electrode11, the collector electrode30, the helix electrode20or heater12of such a traveling wave tube, usually a method as shown inFIG. 10in which an ammeter70is inserted in series between the electrode (inFIG. 10, cathode electrode11) and the power supply apparatus60is considered.

However, high voltage (several kV to several 10 kV) is applied on the cathode electrode, the collector electrode and the heater. Therefore, when measuring the electric current which flows to the cathode electrode, the collector electrode and the heater by using such an ammeter70, it is necessary to conduct secure insulation to the ammeter70in order to perform measurement work safely. It is because high voltage is also applied on the ammeter70.

Further, it is necessary to prepare and use a special measurement apparatus and a special equipment in order to perform measurement of the electric current flowing to each electrode or voltage applied on each electrode of the traveling wave tube. Therefore, it is difficult to measure such electric current and the voltage simply under operating condition of the traveling wave tube.

Japanese Patent No. 2711897 discloses technology about a power supply apparatus which measures an electric current which flows to the collector electrode of the traveling wave tube with providing a special transformer for electric current detection and measurement.

The power supply apparatus according to this technology has a configuration in which the special transformer is inserted in series between a secondary winding (output side) of the voltage conversion transformer and the rectifier circuit. A couple of primary windings of this special transformer are inserted in series at the output side (secondary winding) of the voltage conversion transformer, and the output side (secondary winding) of the voltage conversion transformer is connected with the rectifier circuit. The rectifier circuit outputs a DC voltage having a high voltage value to the cathode electrode and the collector electrode of the traveling wave tube. By such configuration, an electric current, which corresponds to the electric current flowing to the collector electrode of the traveling wave tube, flows to the primary windings of the special transformer, then, at the secondary winding of the special transformer, an electric current which is proportional to the electric current flowing to the primary windings of the special transformer can be measured.

Here, in this power supply apparatus, the cathode current is measured and outputted as the measured current value by applying the following approximation: it is supposed that the helix current and the anode current are negligible small compared with the collector current and the cathode current, and these values are ignored; and it assumes that the cathode current is equal to the collector current.

SUMMARY

An exemplary object of the present invention is to provide an electric current measurement apparatus, a voltage measurement apparatus and a power supply apparatus equipped with these apparatus which can safely and simply measure an electric current flowing to each electrode and voltage applied on each electrode.

An electric current measurement apparatus for measuring an electric current flowing to a desired electrode of an electron tube according to an exemplary aspect of the invention includes a transformer having a primary winding of input side and a secondary winding of output side; a detection resistor connected in series in an ampere meter route of the desired electrode through which a measurement target electric current flows; a voltage detection unit which detects electric potential difference at the detection resistor and outputs pulse signals having pulse attribute corresponding to a detected value of the electric potential difference; a switching part connected between two wirings of the secondary winding of the transformer for providing a short circuit of the secondary winding according to the pulse signals outputted from the voltage detection unit; and a measurement current value output unit which measures pulse attribute of pulse-shape electric currents being induced on the primary winding of the transformer caused by intermittent short circuit of the secondary winding provided by the switching part, and outputs a value of the measurement target electric current flowing through the detection resistor based on a measurement result of the pulse attribute of the pulse-shape electric currents with referring to a predetermined relationship between a value of the electric current flowing through the detection resistor and the pulse attribute of the pulse signals generated in the voltage detection unit.

EXEMPLARY EMBODIMENT

In the following explanation, it is described about an electric current measurement apparatus and a voltage measurement apparatus for each electrode of the traveling wave tube as an example, however, the present invention can also be applied to an electric current measurement apparatus which measures the electric current flowing to each electrode of other types of electron tube and a voltage measurement apparatus which measures the voltage applied on each electrode of other types of electron tube.

A First Exemplary Embodiment

FIG. 1is a block diagram showing one exemplary configuration of the embodiment of an electric current measurement apparatus.

The electric current measurement apparatus of this embodiment is included in a heater power supply, which generates the heater voltage (Eh) to be supplied to a heater, among a plurality of DC voltage sources provided in the power supply apparatus100which supplies predetermined DC voltage to each electrode of the traveling wave tube1.

As shown inFIG. 1, the heater power supply includes an inverter102, a transformer101and a rectifier circuit103. The inverter102converts a DC voltage supplied from outside into an AC (alternating current) voltage, and inputs the AC voltage to a primary winding of the transformer101. The transformer101performs voltage conversion of the AC voltage inputted to the primary winding, and outputs an AC voltage having a desired voltage value from the secondary winding. The rectifier circuit103converts the converted AC voltage outputted from the secondary winding of the transformer101into a DC voltage having a desired voltage value of each electrode. Because the transformer101, the inverter102and the rectifier circuit103as the composition of a DC voltage source are well-known configurations, the detailed description will be omitted here.

The electric current measurement apparatus110includes the transformer101, a detection resistor Rs114, a voltage detection unit111, a switching part113and a measured current value output unit112.

The detection resistor Rs114is provided and connected in series in an ampere meter route of a desired electrode through which a measurement target electric current flows to the desired electrode of the traveling wave tube. Electric potential difference occurs between both ends of the detection resistor Rs114by the measurement target electric current flowing through the detection resistor Rs114.

The voltage detection unit111detects the electric potential difference between both ends of the detection resistor Rs114, and outputs pulse signals. These pulse signals outputted from the voltage detection unit111have pulse attribute corresponding to a detected value of the electric potential difference. As will be described later, the pulse attribute changes proportionally to the detected electric potential difference.

The switching part113is connected between two wirings of a secondary winding of the transformer. The switching part113provides a short circuit of the secondary winding when the switching part113turns on, and the switching part113repeats turning on and off according to the pulse signals outputted from the voltage detection unit111. Therefore, the secondary winding of the transformer101is intermittently short-circuited.

The measured current value output unit112measures pulse attribute of pulse-shape electric currents which are induced on the primary winding of the transformer101. The pulse-shape electric currents are induced by the intermittent short circuits of the secondary winding provided by the switching part113. That is, two wirings of the second winding side are connected and disconnected repeatedly, and it causes the pulse-shape electric currents to be induced at the primary winding side. The pulse attribute of pulse-shape electric currents corresponds to how intermittently short-circuit at the secondary winding side. Then, the measured current value output unit112outputs a value of the measurement target electric current flowing through the detection resistor Rs114based on the measurement result of the pulse attribute. At this time, the measured current value output unit112calculates the value of the measurement target electric current with referring to a predetermined relationship between a value of the electric current flowing through the detection resistor Rs114and the pulse attribute of the pulse signals generated in the voltage detection unit111.

In more detail, the voltage detection unit111includes a detection circuit121and a pulse generating circuit122. The detection circuit121detects the electric potential difference having occurred between both ends of the detection resistor Rs114. The pulse generating circuit122generates pulse signals. The pulse attribute of the pulse signals changes according to an output voltage value that indicates electric potential difference detected by the detection circuit121. The measured current value output unit112includes a pulse detection circuit123and an arithmetic calculation unit124. The pulse detection circuit123detects the pulse-shape electric currents flowing on the primary winding of the transformer101. The pulse-shape electric currents are induced by the intermittent short circuits of the secondary winding provided by the switching part113. The arithmetic calculation unit124measures the pulse attribute of the pulse-shape electric currents detected by the pulse detection circuit123and calculates a value of electric current flowing through the detection resistor Rs114with referring to a predetermined relationship between a value of the electric current flowing through the detection resistor Rs114and the pulse attribute of the pulse signals generated in the pulse generating circuit122.

The transformer101to be used for this exemplary embodiment shares the voltage conversion transformer provided in the heater power supply.

As shown inFIG. 1, the detection resistor Rs114is inserted, for example, between the cathode electrode and a common negative electrode of the helix power supply104and the collector power supply105. The helix power supply104generates the helix voltage (Ehel) and the collector power supply105generates the collector voltage (Ecol). In this case, the cathode current of the traveling wave tube1can be measured.

When measuring the collector current of the traveling wave tube1, the detection resistor Rs114is inserted between a negative electrode of the collector power supply105and the cathode electrode of the traveling wave tube1as shown inFIG. 2. When measuring the helix current of the traveling wave tube1, the detection resistor Rs114is inserted between a negative electrode of the helix power supply104and the cathode electrode of the traveling wave tube1as shown inFIG. 3. When measuring the heater current, the detection resistor Rs114is inserted between a negative electrode of the heater power supply and the heater of the traveling wave tube as shown inFIG. 4.

When measuring the anodic current for the traveling wave tube1which has a configuration of no connection between the anode electrode and the helix electrode, the detection resistor Rs114is inserted between a positive electrode of an anode power supply (not shown) and the anode electrode of the traveling wave tube1. It may be equipped with all these detection resistors Rs in the power supply apparatus100at the same time for measuring all types of electric current, and also it may be equipped with only one or some of these detection resistors Rs for measuring one or some types of electric current. When a plurality of detection resistors Rs are provided for measuring a plurality of types of electric current, for example, the detection circuit121and the pulse generating circuit122corresponding to respective detection resistors Rs are also provided and pulse signals outputted from a plurality of pulse generating circuits112may be supplied to the switching part113successively by using a multiplexer or the like.

The detection circuit121detects the electric potential difference having occurred between both ends of the detection resistor Rs114, and outputs a detection voltage value according to magnitude of the electric potential difference. The detection circuit121includes a buffer circuit which amplifies the input electric potential difference as required and outputs the amplified electric potential difference.

The pulse generating circuit122can be composed by, for example, a V/F converter (voltage/frequency transducer), VCO (Voltage Controlled Oscillator), a PWM (Pulse Width Modulation) circuit or a PDM (Pulse Density Modulation) circuit, which are all well-known apparatus. The pulse generating circuit122generates pulse signals in which the pulse attribute (such as frequency, the cycle, the pulse width and the pulse density) changes according to the detection voltage value outputted from the detection circuit121. Further, as will be described later, a pulse-shape electric current, which has the same pulse attribute as the pulse signal generated by the pulse generating circuit122, flows on the primary winding of the transformer101. Therefore, it is desirable to set a frequency and pulse width of the pulse signal generated in the pulse generating circuit122in order to distinguish a pulse-shape electric current of the measuring target from the pulse signal of operating current of the inverter102. Specifically, it is desirable for the pulse signal generated in the pulse generating circuit122that the frequency is sufficiently lower than the switching frequency of the inverter102and the pulse width is sufficiently narrower than the switching cycle of the inverter102.

As shown inFIG. 1, for example, the switching part113includes a transistor Q1which is inserted between two wirings of the secondary winding of the transformer101, i.e., an emitter and a collector are connected to the respective wirings, and provides a short circuit for the secondary winding of the transformer101by turning on/off of the transistor Q1according to the pulse signals outputted from the pulse generating circuit122. Further, an inductor L1exemplary shown inFIG. 1is connected between the collector of the transistor Q1and one of wirings of the second winding. This inductor L1is provided for reducing a short circuit current which flows when turning on the switch103(transistor Q1), and this inductor L1may be replaced by a resistor. If the performance of the transistor Q1and the transformer101is not degraded by the short circuit current, it is not necessary to provide the inductor L1or a resistor. A MOS (Metal Oxide Semiconductor) transistor, a relay or the like can be used for the switching part113instead of the transistor Q1.

The short circuit current flows intermittently on the secondary winding of the transformer101while the switching part113repeats turning on/off by the pulse signals outputted from the pulse generating circuit122. As a result, pulse-shape electric currents are induced on the primary winding of the transformer101. The pulse detection circuit123detects these pulse-shape electric currents induced on the primary winding of the transformer101by using, for example, a well-known current probe, and outputs the detection result to the arithmetic calculation unit124.

The arithmetic calculation unit124includes a well-known pulse counter and a pulse width measurement apparatus or the like in addition to, for example, CPU (Central Processing Unit), a DSP (Digital Signal Processor) or various logic circuits which operates according to software programs. The arithmetic calculation unit124measures the pulse attribute (such as frequency, the cycle, the pulse width and the pulse density) of pulse-shape electric currents detected in the pulse detection circuit123by using a pulse counter and a pulse width measurement apparatus or the like, and calculates an electric current value which flows through the detection resistor Rs114based on the measurement result.

Next, operation of the electric current measurement apparatus according to this exemplary embodiment will be described with reference to drawings.

FIG. 5Ais a schematic diagram showing an example of pulse shape outputted from the pulse generating circuit122shown inFIG. 1.FIG. 5Bis a schematic diagram showing an example of current waveform detected in the pulse detection circuit123.

As mentioned above, the detection circuit121outputs the voltage value proportional to an electric current (the cathode current in case of a configuration shown inFIG. 1) flowing through the detection resistor Rs114. The pulse generating circuit122outputs pulse signals having the pulse attribute corresponding to the voltage value received from the detection circuit121. The pulse attribute changes proportionately to the output voltage value of the detection circuit121.FIG. 5Ashows an example that the higher voltage value outputted from the detection circuit121results the higher frequency pulses (a pulse interval is narrow) being outputted from the pulse generating circuit122. The switching part113repeats turning on/off according to these pulse signals outputted by the pulse generating circuit122. When the switching part113repeats turning on/off, pulse-shape short circuit currents flow on the secondary winding of the transformer101, and the pulse attribute of the pulse-shape short circuit currents is proportional to the value of the cathode current.

When the pulse-shape short circuit currents intermittently flow on the secondary winding of the transformer101, pulse-shape electric currents having the same pulse attribute as the short circuit currents on the secondary winding are induced and flow on the primary winding of the transformer101(refer toFIG. 5B).

According to this exemplary embodiment, the pulse-shape electric currents flow on the primary winding of the transformer101is detected by the pulse detection circuit123, and the cycle T of the pulse-shape electric currents is measured by the arithmetic calculation unit124. Here, as shown inFIG. 5B, not only the pulse-shape electric currents but also the pulse signals of operating current of the inverter102also flow on the primary winding of the transformer101. Therefore, the arithmetic calculation unit124sets a predetermined detection level in advance, and detects the pulse-shape electric current beyond the detection level as a measuring target electric current corresponding to the short circuit current of the secondary winding of the transformer101.

The cycle T of the pulse-shape electric currents obtained on the primary winding side of the transformer101is equal to the cycle (frequency) of the short circuit currents flowing on the secondary winding of the transformer101as mentioned above, and the frequency is proportional to the cathode current value detected by the detection circuit121.

Accordingly, when a relationship between an electric current which flows through the detection resistor Rs114and a pulse signal generated in the pulse generating circuit122is known in advance, the cathode current value of the traveling wave tube1is obtained by measuring the cycle (frequency) T of the pulse-shape electric currents flowing on the primary winding of the transformer101. For example, the detected voltage value is obtained from the measured cycle T with referring to the relationship between the voltage value detected by the detection circuit121and pulse signal attribute of the pulse signal generated in the pulse generating circuit122, and the cathode current value is obtained by dividing the detected voltage value by a resistance value of the detection resistor Rs114.

When arranging the detection resistor Rs114in each of desired positions as shown inFIGS. 1-4, the value of the electric current flowing to a desired electrode of the traveling wave tube1can be obtained according to the arranged position of the detection resistor Rs114. That is, the collector current, the helix current and the heater current can also be obtained.

Further, in this exemplary embodiment, an example is shown for the case that the electric current measurement apparatus110is incorporated in the heater power supply. This is because the heater voltage is a relatively low voltage (−6.3V, for example), and it can be used as the power supply voltage for the detection circuit121and the pulse generating circuit122just as it is without changing an operation voltage for these circuits. If the power supply voltage for operating the detection circuit121and the pulse generating circuit122can be generated, the electric current measurement apparatus110of this exemplary embodiment may be included in any of the helix power supply104and the collector power supply105.

According to this exemplary embodiment, the value of electric current which flows to a desired electrode (cathode electrode, helix electrode, collector electrode, heater or anode electrode) of the traveling wave tube1is obtained by measuring the pulse attribute of the pulse-shape electric currents flowing on the primary winding of the transformer101. Therefore, the electric current which flows to any of the desired electrodes of the traveling wave tube1safely and simply can be measured without performing necessary treatment for handling high voltage such as an insulation treatment.

Each of the cathode current, the collector current, the helix current, the heater current and the anode current can be measured individually by inserting the detection resistor Rs114in series in an appropriate ampere meter route through which an electric current of the measurement target flows. Therefore, the electric current flowing to each electrode of the traveling wave tube1can be measured with relatively high accuracy.

A Second Exemplary Embodiment

According to the first exemplary embodiment mentioned above, the configuration for measuring the cathode current, the collector current, the helix current, the heater current and the anode current of the traveling wave tube1by detecting electric potential difference at both ends of the detection resistor Rs114which occurs by electric currents flowing through detection resistor Rs114is shown.

The second exemplary embodiment is proposed about a voltage measurement apparatus for measuring the helix voltage, the collector voltage, the heater voltage and the anode voltage supplied to the traveling wave tube1.

FIG. 6is a block diagram showing one exemplary configuration of the voltage measurement apparatus according to the second exemplary embodiment.

As shown inFIG. 6, instead of the detection resistor Rs114shown inFIG. 1, the voltage measurement apparatus120of this exemplary embodiment is provided with a voltage dividing resistor116which includes resistors R1and R2.

The voltage measurement apparatus120includes a transformer101having a primary winding of input side and a secondary winding of output side, and this transformer101is shared by the voltage conversion transformer provided in the power supply apparatus100. The voltage dividing resistor116is connected in parallel with target voltage measurement points for dividing a measurement target voltage by using at least two resistors, i.e., resistors R1and R2in this case. The voltage detection unit111detects a divided voltage of the measurement target voltage and outputs pulse signals. The pulse signals outputted from the voltage detection unit111have pulse attribute corresponding to a detected value of the divided voltage. The switching part113has the same configuration and the same function as the first exemplary embodiment, and it is connected between two wirings of the secondary winding of the transformer for providing a short circuit of the secondary winding according to the pulse signals outputted from the voltage detection unit. The measured voltage value output unit115measures pulse attribute of pulse-shape electric currents. The pulse-shape electric currents are induced on the primary winding of the transformer by the same principle as the first exemplary embodiment. The measured voltage value output unit115outputs a value of the measurement target voltage based on the measurement result of the pulse attribute with referring to a predetermined relationship among a voltage dividing ratio of the voltage dividing resistor116, a voltage value of the divided voltage and the pulse attribute of the pulse signals generated in the voltage detection unit111.

In more detail, the voltage detection unit111includes a detection circuit121and a pulse generating circuit122. The detection circuit121detects the divided voltage of the measurement target voltage and outputs the detected voltage value corresponding to the detected value of the divided voltage. The pulse generating circuit122generates the pulse signals having pulse attribute which changes proportionally to the detected voltage value outputted from the detection circuit121. The measured voltage value output unit115includes a pulse detection circuit123and an arithmetic calculation unit125. The pulse detection circuit123detects the pulse-shape electric currents flowing on the primary winding of the transformer which are induced by intermittent short circuit of the secondary winding provided by the switching part113. The arithmetic calculation unit125measures the pulse attribute of the pulse-shape electric currents detected by the pulse detection circuit123, and outputs the value of the measurement target voltage based on the measurement result of the pulse attribute with referring to the predetermined relationship among the voltage dividing ratio of the voltage dividing resistor116, the voltage value of the divided voltage detected by the detection circuit121and the pulse attribute of the pulse signals generated in the pulse generating circuit122.

As a measurement target voltage, the helix voltage, for example, is divided by the resistors R1and R2of the voltage dividing resistor116which are connected in parallel with target voltage measurement points, i.e., between the helix electrode and the negative electrode of the helix power supply104. The divided voltage by the voltage dividing resistor116is detected by the detection circuit121. The detection circuit121inputs the divided voltage which is divided by the voltage dividing resistor116, and includes a buffer circuit for outputting the detected voltage with amplified or attenuated.

When the collector voltage of the traveling wave tube is measured, the voltage dividing resistor116including resistors R1and R2is inserted, for example, between the cathode electrode and the collector electrode as shown inFIG. 7. When the heater voltage is measured, the voltage dividing resistor116including resistors R1and R2is inserted between the cathode electrode and the heater as shown inFIG. 8as the target voltage measurement points. Further, when the anode voltage of the traveling wave tube, in which the anode electrode is not connected to the helix electrode, is measured, the voltage dividing resistor116including resistors R1and R2is inserted between the cathode electrode and the anode electrode as the target voltage measurement points. It may be equipped with all these voltage dividing resistors116including the resistors R1and R2in the power supply apparatus100for measuring all types of voltage, and also it may be equipped with only one or some of these voltage dividing resistors116including the resistors R1and R2for measuring one or some types of voltage. When a plurality of voltage dividing resistors116including the resistors R1and R2are provided for measuring a plurality of types of voltage, for example, the detection circuit121and the pulse generating circuit122corresponding to respective voltage dividing resistors116are also provided and pulse signals outputted from a plurality of pulse generating circuits112may be supplied to the switching part113successively by using a multiplexer or the like.

The operating principle of the voltage measurement apparatus of this second exemplary embodiment is same as the electric current measurement apparatus of the first exemplary embodiment.

The detection circuit121detects the divided voltage between both end points of the resistor R2of the voltage dividing resistor116, and outputs a detected voltage value. The pulse generating circuit122generates the pulse signals in which the pulse attribute (such as frequency, the cycle, the pulse width and the pulse density) proportionally changes according to the output voltage value of the detection circuit121. The switching part113repeats turning on/off according to the pulse signals outputted from the pulse generating circuit122. When the switching part113repeats turning on/off, the pulse-shape short circuit currents flow on the secondary winding of the transformer101, and the pulse attribute of the pulse-shape short circuit currents is proportional to the detected voltage value.

When the pulse-shape short circuit currents intermittently flow on the secondary winding of the transformer101, the pulse-shape electric currents having the same pulse attribute as the short circuit currents on the secondary winding are induced and flow on the primary winding of the transformer101. The pulse-shape electric currents flow on the primary winding of the transformer101are detected by the pulse detection circuit123, and the cycle T of the pulse-shape electric currents is measured by the arithmetic calculation unit125.

The cycle T of the pulse-shaped electric currents obtained on the primary winding of the transformer101is equal to the cycle (frequency) of the short-circuit currents which flow on the secondary winding of the transformer101, and the frequency is proportional to the voltage value detected by the detection circuit121.

Accordingly, when a relationship among a voltage dividing ratio of the voltage dividing resistor116, a voltage value detected by the detection circuit121and a pulse signal generated in the pulse generating circuit122is known in advance, the voltage value of the measuring target is obtained by measuring the cycle (frequency) T of the pulse-shape electric currents flowing on the primary winding of the transformer101. For example, the detected voltage value is obtained from the measured cycle T with referring to the relationship between the voltage value detected by the detection circuit121and pulse signal attribute of the pulse signal generated in the pulse generating circuit122, and the voltage value of the measuring target is obtained by multiplying the detected voltage value and a figure which is determined by the voltage dividing ratio of the voltage dividing resistor116.

Further, inFIGS. 6-8, an example configuration of the voltage dividing resistor116is shown for the case that two resistors R1and R2connected in series are used for dividing the voltage supplied between two electrodes of the traveling wave tube1, however, it does not matter how many resisters are used as far as it can provide the divided voltage of the measuring target voltage to the detection circuit121.

Because other configuration and operation are the same as that of the first exemplary embodiment, the description will be omitted.

According to this exemplary embodiment, the value of the voltage applied between desired electrodes of the traveling wave tube1is obtained by measuring the pulse attribute of the pulse-shape electric currents induced on the primary winding of the transformer101. Therefore, the applied voltage between the desired electrodes of the traveling wave tube can be measured safely and simply.

The related art described in Japanese Patent No. 2711897 in the background art causes a problem, such that cathode current cannot be measured with high accuracy. Because, in the power supply apparatus according to Japanese Patent No. 2711897, it is supposed that the helix current and the anode current are sufficiently small values compared with the collector current and the cathode current and they are ignored in the measurement, and the cathode current is measured based on the approximation of assuming the cathode current value to be equal to the collector current value.

Also, the related art described in Japanese Patent No. 2711897 causes another problem, such that the helix current and the anode current cannot be measured because they are not considered as measurement targets. In particular, it is desirable to be able to simply measure the helix current because the helix current is the important value to be used for estimating the operating life of the traveling wave tube.

Further, in Japanese Patent No. 2711897, nothing is described about a method to measure the applied voltage to the cathode electrode, the collector electrode, the anode electrode and the heater of the traveling wave tube.

An exemplary advantage according to the invention is that the electric current measurement apparatus and the voltage measurement apparatus which can safely and simply measure an electric current and high voltage applied on each electrode of the electron tube are realized, and also the power supply apparatus including the electric current measurement and the voltage measurement apparatus which supplies high voltage to each electrode of the electron tube is realized.

Further, it is the inventor's intention to retain all equivalents of the claimed invention even if the claims are amended during prosecution.