Reflex klystron oscillator. • Reflex klystron: It is used as oscillator.
Reflex klystron oscillator It operates on the principle of velocity modulation of an electron beam. It generates microwave Apr 27, 2018 · Hill, C. be/WiVC-av9i2o May 30, 2023 · In such a multi-cavity klystron, the intermediate cavities (known as ‘intermediate cavities’ or ‘drift tubes’) contribute to further bunching of the electron beam, thus increasing the efficiency and gain of the klystron. Magnetrons powered the transmitters. With the help of physics positive feedback nature of Reflex Klystron, the growth of oscillation leading to its spectral purification and In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids. In their return journey, the electrons give Jan 5, 2021 · Reflex Klystron Amplifier. A single-cavity klystron in which the electron beam is reflected back through the cavity resonator by a repelling electrode having a negative voltage; used as a microwave oscillator. An X-band klystron oscillator structure is assembled with a CNT cold The electron beam is turned around by a negatively charged electrode that repels the beam. G. Use Reflex Klystron calculator to find the value of the output power,repeller voltage & efficiency of any reflex klystron tube using the operating frequency and few other parameter of klystron oscillator. Reflex Klystron is a single cavity apparatus. Q11. be/oW9xPxZ1iu0Lec-94 : https://youtu. field producing the bunching of electrons and also conversing (a fraction of) the kinetic energy of the electrons into h. The cavity resonator must be flexible on at least one wall due to the tolerances of the tube manufacturer. Reflex Klystron is an oscillator commonly classified under the categories of differential negative conductance oscillators, like Tetrode Oscillator, Gunn Oscillators etc. Working : The RF voltage that is produced across the gap by the cavity oscillations act on the electron beam to cause velocity modulation. Oct 16, 2023 · Q10. 2 Bench setup for Characteristics of Reflex Klystron. It uses the The reflex klystron is mostly used as a microwave oscillator; it works as a local oscillator in the microwave receiver circuits. Structure of Reflex klystron2. Answer : a. • Reflex klystron: It is used as oscillator. The inductance is. Reflex Klystron tube with mount 3. 169M 2 i 1 /G c V o , where M is the coefficient of modulation of the gap, i 1 is the effective current, G c is the shunt conductance of the unloaded resonator, and V o is the beam voltage. Principles of Two-Cavity Klystrons Two-Cavity Klystron Geometry. 20. F generator in the microwave transmitter circuits. Not an oscillator: This statement is not true because the primary function of a reflex klystron is indeed as an oscillator. For proper working as an oscillator the output voltage needs to be fed back to the input and if positive feedback is taken then only the klystron will oscillate. The reflex version of the klystron, perfected at Sperry and in British laboratories, served as the local oscillator in superheterodyne radar receivers. 8. Learn how it works, its construction, specifications and applications in microwave engineering. This negative element is the repeller mentioned earlier. Due to its geometry and long drift space, it suffered from mode jumping through the tuning range. The main difference between two cavity reflex klystron amplifier and reflex klystron is that the output cavity is omitted in reflex klystron and the repeller or reflector electrode, placed a very short distance from the single Jun 21, 2018 · In reflex klystron oscillator which has only one cavity, the above problems are removed; however, it gives low power (less than 2 W) only in the range 1–25 GHz. Explanation: Reflex klystron is a single cavity klystron tube that operates as on oscillator by using a reflector electrode after the cavity to provide positive feedback via the electron beam. The main difference between two cavity reflex klystron amplifier and reflex klystron is that the output cavity is omitted in reflex klystron and the repeller or reflector electrode, placed a very short distance from the Apr 13, 2022 · This paper presents the design and fabrication of a reflex klystron oscillator based on a carbon nanotube (CNT) cold-cathode. The figure-2 depicts two cavity klystron. With the help of physics positive feedback nature of Reflex Klystron, the growth of oscillation leading to its spectral purification and Reflex Klystron is an oscillator commonly classified under the categories of differential negative conductance oscillators, like Tetrode Oscillator, Gunn Oscillators etc. be/nwzTOSZ2p Reflex Klystron is used as a low-power Microwave oscillator. For maximum power output and Unfortunately the Bell klystron design was delayed for some reasons and REL had to switch to a Rogers re-design of the Sutton tube, the Type 8, for the local oscillator of the receiver. Reflex klystron has low power and efficiency, and its frequency can be varied by changing the transit time of electrons. Q12. The procedure measures power and frequency at Reflex Klystron is an oscillator commonly classified under the categories of differential negative conductance oscillators, like Tetrode Oscillator, Gunn Oscillators etc. 9 - US reflex low-power klystron intended for use as local oscillator in radar receivers. An X-band klystron oscillator structure is assembled with a CNT cold-cathode electron gun with an electrostatic focusing, a re-entrant cavity as anode, and a repeller. An equivalent circuit for a reflex-klystron oscillator based on the method outlined above, is shown in Fig. be/yj9Ca8mT-lM This klystron can be used as an amplifier. Velocity Modulation . be/8qWKmQEoTjILec-91 : https://youtu. Features: Rigid design; Shear strength; Precisely engineered; EXPERIMENTS : • To study the Jan 12, 2020 · Subject - Microwave EngineeringVideo Name - Output Power and Efficiency in Reflex KlystronsChapter - Microwave Linear Beam Tubes O TypeFaculty - Prof. The effect of the bunched electron beam is treated Nov 20, 2016 · A klystron is a vacuum tube that can generate or amplify power at microwave frequencies. With the help of physics positive feedback nature of Reflex Klystron, the growth of oscillation leading to its spectral purification and Oscillator output energy is then taken from the cavity. The reflex klystron is a single cavity variable frequency microwave generator of low power and low efficiency. The time required for an electron to emit from the cavity gap and again to come back to the cavity gap from the repeller anode is called a round trip transit time. Shorting plate 8. Dec 13, 2015 · Abstract: Reflex Klystron Oscillator has been studied again to explore the effects of considering bunching parameter X greater than one. 5. The theory of reflex-klystron oscillators is given in detail. (2) Draw the Applegate diagram with gap voltage for a reflex klystron. Reflex klystron Applegate diagram4. Question: (d) A reflex klystron oscillator operates at the peak of the mode n=2 and maximum output power with the following parameters: V0=600 V,I0=20 mA,Vr=250 V,L=1 mm. AIM: To study the characteristics of the reflex klystron tube and to determine its electronic tuning range. In 1941 in England EMI started improving the Sutton design, reducing the diameter of the interaction gap to 2 mm and using a much smaller reflector placed very This paper describes a theoretical and experimental investigation of a special form of klystron which seems to have many important uses as a frequency-modulated oscillator. Let us now start a new topic, which is reflex klystron. Jul 22, 2021 · A reflex klystron is a low-power vacuum tube that produces microwave oscillations by velocity and current modulation. • Reflex Klystron: Used as Oscillator. The electron gun adopts a convex CNT film emitter as the cathode. 2. Jan 31, 2019 · Since the most noticeable feature of a reflex klystron is its resonant cavity, a convenient grouping is according to the location of the cavity; that is, whether it is built into the tube (integral cavity), or external to it (external cavity). 1 ¾ and 2 ¾ are the most commonly used modes in a practical reflex klystron. Klystron power supply SKPS – 610 2. 3 REFLEX KLYSTRON OSCILLATOR The electron gun emits the electron beam, which passes through the gap in the anode cavity. Frequency meter XF-710 6. 7. Apr 22, 2021 · Reflex Klystron functioningMechanism of OscillationModes of OscillationMode Curves (or Pushing Figure) Microwave EngineeringExpression for output power of Reflex Klystron oscillator Lec-91 : https://youtu. The development of the British reflex klystron . Some May 28, 2021 · About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket Press Copyright Comparing the mechanism of reflex klystron and Barkhausen-Kurz oscillators, we found them principally to be the same. The cavity resonator and its coupled load are repre sented by the parallel resistance-inductance-capacitance circuit. Aim: To calculate the impedance of the given load of the Klystron. be/BxzQSMlzqDQ In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids. Apparatus: 1. The reflex klystron amplifier is used as an oscillator in a modulator in microwave transmitters and radar receivers. Reflex Klystron: Reflex klystron is a klystron with a single-cavity which acts as an oscillator by using a reflector electrode next to the cavity to deliver positive feedback through the electron beam. The important Jun 1, 2013 · Reflex Klystron: So basically what was the need for reflex klystron when we had multicavity klystron? Lets consider 2-cavity klystron oscillator. Klystron tube 2k25 3. - Functional diagram of a reflex klystron. The Sutton tube, the first reflex klystron oscillator . Reflex klystron has already been dealt in detail in Chap. In the year 1937, American engineers Russell and Sigurd Varian developed klystrons. Isolator or Circulator or Attenuator 4. (i) EQUIPMENT AND COMPONENTS: 1. 20 3 Measurement of frequency and Guide wavelength calculation: 1)Verification of the relation between Guide wavelength, free space This type of klystron oscillator is called a reflex klystron because of the reflex action of the electron beam. er is the reference electron taken as the one that passes the gap on its way to the repeller at the time when the gap voltage is zero and going negative. Find out how the transit time, the gap voltage and the modes affect the performance and efficiency of this device. UNIT II-MICROWAVE COMPONENTS (9 hours) Dec 1, 2015 · Reflex Klystron is an oscillator commonly classified under the categories of differential negative conductance oscillators, like Tetrode Oscillator, Gunn Oscillators etc. was the first reflex klystron designed by Western Electric for the 10-cm band, Introduced in the second half of 1941, it was characterized by greater efficiency and stability against the British NR89, due to the reduced drift space and Jun 21, 2018 · Reflex klystron is vacuum tube microwave oscillator, the operation of which depends on the principle of electron velocity modulation. All the differences in the Reflex Klystron Oscillators (1) Explain the principle of operation of reflex klystron oscillator with neat sketch. Different characteristics of reflex klystron can be determined using the whole associated package for reflex klystron experiments. Also known as reflex oscillator. 17 APPARATUS Klystron power supply, Klystron tube, Isolator, Variable attenuator, Detector mount, Wave guide stand, VSWR meter and BNC cable. Reflex klystron working3. Reflex Klystrons are widely used in radar systems, microwave communication, and signal generation due to their simplicity, compactness, and efficiency in producing high-frequency oscillations. Figure 9-4-2 shows an Applegate diagram for the 1~ mode of a reflex klystron. So 2-cavity klystron is called an amplifier. But 2-cavity klystron oscillator is not used because the slight change in frequency is Reflex Klystrons: * A schematic diagram of a reflex klystron is shown in Fig. The bunched electrons then pass through the gap again, transferring kinetic energy to the electromagnetic field in the cavity. Microwave frequencies are millimeter waves so we need to generate them through Amplifiers or Oscillators,in this video we will learn generation of microwave 1 Characteristics of Reflex Klystron oscillator, finding the mode numbers and efficiencies of different modes. Learn about the construction, operation and applications of reflex klystron, a microwave generator that uses reflections and oscillations in a single cavity. Mar 5, 2018 · 3. 81–82, 2006. A reflex klystron is a type of klystron that acts as an oscillator rather than an amplifier. 01 μ H/m. 1 μ H/m d) 0. II. This type of klystron oscillator is called a reflex klystron because of the reflex action of the electron beam. Learn how a reflex klystron oscillator produces microwave oscillations by using a single cavity and a repeller electrode. as local oscillator in microwave radar receivers . Variable attenuator . Local oscillator in microwave receivers 1. For this article, however, we will focus on another popular type: the two-cavity klystron. Reflex Klystron is utilized as an oscillator. The two-cavity oscillator klystron normally generates more power than the reflex klystron—typically watts of output rather than milliwatts. The velocity-modulation process takes place as before, but analysis shows that in the retarding field used to reverse the direction of electron motion, the phase of the current wave is exactly opposite to that in the two-cavity klystron. Sutton of Signal School group at the Bristol University. THE EQUIVALENT CIRCUIT OF A REFLEX-KLYSTRON OSCILLATOR . The difference between reflex and two/multi cavity klystron is that, reflex klystron uses single cavity for modulation/demodulation. Assume that the transit time τg through the gap and the beam loading can be neglected. The electrons are finally collected by the walls of the cavity or other grounded metal parts of the tube. 10 hours ago · A Reflex Klystron is a type of vacuum tube used to generate and amplify microwave signals. Mar 30, 2023 · Microwave EngineeringCharacteristics and applications of Reflex Klystron oscillatorLec-93 : https://youtu. The analysis is similar to earlier explanations of electron bunching in a field-free drift space and predicts a similar current distribution when bunching takes place in a reflecting field. The analysis of a reflex klystron is similar to that of a two-cavity klystron. 16 2 Characteristics of Gunn diode oscillator, Power Output Vs Frequency, Power Output Vs Bias Voltage. In the first cavity, an alternating electric field bunches the electrons. This is most widely used in applications where variable frequency is desired as. , whereas the Barkhausen … Expand Nov 12, 2020 · #ReflexKlystron#Klystron#MicrowaveOscillator The document describes the mode characteristics of a reflex klystron oscillator. APPARATUS 1. REFLEX KLYSTRON CHARACTERISTICS I. Among them, two samples of the early reflex klystrons developed at the Signal School in 1940 by Robert Sutton and tubes other American factories. 9. Lec 31: Ferrite Devices; Introduction to Microwave Integrated Circuits (MIC) Lec 32: Planar transmission lines for MIC; Lec 33: Lumped elements for MIC Mar 25, 2022 · #microwave #oscillator #velocitymodulation #VivekRatnaparkhi #MicrowaveTubes #ReflexKlystronAnalysisMathematical analysis of velocity modulation in Reflex Kl A reflex klystron consists of an electron gun, a cavity with a pair of grids and a repeller plate as shown in the above diagram. The cavity resonator and its coupled load are repre-sented by the parallel resistance-inductance-capacitance circuit. Reflex Klystron is a single cavity variable frequency generator of low power and low efficiency . SUBCARRIER MODULATION OF A REFLEX KLYSTRON J. The Sutton tube was developed as a local oscillator for the receiver of 10cm microwave radar sets. It is observed that as X exceeds unity, the relation between the departure time and the arrival time of the bunched electrons becomes as multivalued function and the Fourier component of the beam current comprises not only the in phase term but also Reflex Klystron is explained with the following points:1. be/5GQjGdOmmtwLec-92 : https://youtu. Reflex klystrons can be tuned mechanically to adjust the cavity size. (3) Explain the electronic admittance of the gap in the case of reflex klystron. Reflex Mar 27, 2023 · Microwave EngineeringMathematical analysis of Reflex Klystron oscillatorLec-90 : https://youtu. It is shown that maximum efficiency for small amplitudes is given by η = 0. Since there is no reflector, only one high-voltage supply is required; however, to cause the tube to oscillate, the voltage must be adjusted to a particular value. The figure-1 depicts two-cavity klystron. , whereas the Barkhausen oscillator is categorized under the positive feedback system. There are no two identical reflex klystrons, even if they are manufactured in the same series. working of reflex klystron #microwaveengineering #reflexklystron #microwavelabRaviteja Creative Catchers !!Please Like share & subscribe !!Reflex Klystron CharacteristicsMode Character #microwave #oscillators #reflex #klystron #VivekRatnaparkhi #MicrowaveTubes #EfficiecnyofReflexKlystronExpression for Output Power and Efficiency of Reflex K Introduction to microwave transmission – Application and limitation – Klystron amplifier – Reflex Klystron Oscillator – TWT amplifiers – Magnetron Oscillator – Gunn oscillator. It consists of an electron beam emitted from a cathode, two metal cavity resonators, and a collector. The reflex klystron is also called as Sutton tube invented by Robert Sutton. Basically, the operating principle of Klystron is such that the kinetic energy of a moving electron beam is utilized for amplifying and generating microwave signals. The 3K27 reflex klystron, for example, is an integral cavity type and is illustrated in Fig. a) one cavity resonator b) two cavity resonators c) three cavity resonators d) none of the above. Reflex Klystron. Google Scholar The Reflex Klystron utilizes velocity modulation to convert regular electron beam energy into microwave power. Isolator XI-621 5. There are two configurations for a low-powered klystron. • Multi cavity klystron: There are few intermediate cavities used between buncher cavity and catcher cavity. Frequency range: 4GHz – 200GHz Output power: maximum 3W in X-band to 10mW at 220GHz. Vaibha As power oscillator (5 - 50 GHz) if used as a klystron amplifier. The two-cavity klystron utilizes an electron source (heater), an anode, and a cathode like a conventional nothing to do with the Barkhausen oscillator, but rather resuhed from the idea of folding an ordinary two-resonator klystron back upon itselfr Nobody really means -- nor did Pierce --that the reflex klystron arose merely asa development of the Barldaausen-Kurz osciUator. Reflex Klystrons: * A schematic diagram of a reflex klystron is shown in Fig. It is a low power tube with a single and work as an oscillator. A coaxial RF cable has a characteristic impedance of 50 Ω and C equal to 40 pF/m. , ‘Investigation of possible multipactor discharge in a klystron input cavity’, in 2006 IEEE International Vacuum Electronics Conference held jointly with 2006 IEEE International Vacuum Electron Sources, pp. Dec 26, 2019 · There are two configurations for a low-powered klystron. But, these devices are replaced by semiconductor microwave In this video, we explore the Characteristics of the Reflex Klystron Oscillator in detail, as outlined in our Microwave Engineering (MWE) lab experiment manu In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids. Mar 26, 2023 · Microwave EngineeringReflex klystron oscillator - Construction - Bunching ProcessLec-89 : https://youtu. What is the operating frequency and power output of a reflex klystron? Ans. Reflex Klystron Microwave Tubes – klystron, reflex klystron, magnetron and TWT Reflex klystron is single cavity variable frequency microwave oscillator Reflex Klystron that works on reflections and oscillations in a single cavity Apr 13, 2022 · This paper presents the design and fabrication of a reflex klystron oscillator based on a carbon nanotube (CNT) cold-cathode. What is a Reflex Klystron Oscillator? Before answering this question, we need to know how the oscillations are generated. f. Derive the expression for power output and efficiency. SET UP FOR REFLEX KLYSTRON CHARACTERISTICS 2K25 KLYSTRON THEORY The reflex klystron is an oscillator tube with built in feedback mechanism. Answer : c. A) 707A. A re-entrant cavity resonating at 8. and Carter, R. Tunable frequency meter 6. be/oW9xPxZ1iu0 Sutton tube was the name given to the first reflex klystron, developed in 1940 by Robert W. • Two cavity klystron: It is used as low power amplifier. It can be tuned by mechanically adjusting the cavity size. It explains the components needed including the klystron tube, power supply, and frequency meter. Slotted section with tunable probe and movable probe carriage 7. They perform a similiar funciton as Reflex Klystron… Fig, 1. Feb 24, 2012 · What is a Gunn Diode Ocillator? A Gunn Diode Oscillator (also known as a Gunn oscillators or transferred electron device oscillator) are a cheap source of microwave power and comprise of Gunn diode or transferred electron device (TED) as their major component. This klystron is totally dissimilar from cavity klystron because it has a single cavity and used for modulation otherwise demodulation. It also works as the R. Foreword - Recently the author found several vacuum tubes probably coming from the dispersed GEC collection, most of which related to the British radar development. The main difference between two cavity reflex klystron amplifier The two-cavity oscillator klystron normally generates more power than the reflex klystron—typically watts of output rather than milliwatts. The document summarizes the working principle of a reflex klystron oscillator. VSWR meter 5. These electrons travel towards the Repeller electrode, which is at high negative potential. a loaded oscillator. Lec 27: RF oscillator; Microwave Tubes. 1. . REFLEX KLYSTRON. A reflex klystron oscillator uses. be/yj9Ca8mT-lMLec-95 : https://youtu. Figure 5: Wiring with a repeller klystron, and an example given low power repeller klystron tube Repeller klystrons are often used in older radar sets as local oscillators or as oscillators in measurement sets. Mar 25, 2022 · #reflex #microwave #oscillators #klystron #VivekRatnaparkhi #MicrowaveTubes #ReflexKlystronConstructional details and operation of Reflex Klystron Oscillator A cavity can be made to fulfill the FREQUENCY STABILIZATION OF A REFLEX KLYSTRON OSCILLATOR 7" conditions (6) by gradually drilling out the coupling holes, eacl~ time checking the results. Together, the magnetron and the klystron made possible airborne S-band radar, a major factor in securing air superiority for the RAF. In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids. a) 1 μ H/m b) 10 μ H/m c) 0. This is widely used in application where variable frequency is desired as: local oscillator in microwave receiver; In radar receiver; Pump oscillator in parametric amplifier; Construction Oct 12, 2024 · While klystron technology can be applied to create amplifiers (such as in multi-cavity klystrons), the reflex klystron itself is designed and used mainly as an oscillator, not an amplifier. 2 and 5. everything RF has the largest selection of online calculators for the RF and Microwave Industry. Klystron mount XM-251 4. A two-cavity klystron amplifier with proper feedback arrangement can be operated as oscillator, but generally the reflux klystron is a single-cavity klystron oscillator. One is a low-power microwave oscillator (Reflex Klystron) and the second is a low-power microwave amplifier (Two Cavity Klystron or Multi Cavity Klystron). Normally the reflex klystron model used in the laboratories is 2K25, as given in figure of Chaps. It is known by this name due to its reflex action of electron beam. The name of this klystron is taken due to its reflex act of electron beam. Feb 15, 2021 · Reflex klystron and Working of Reflex klystron. The direct influence of the modulation on the klystron through the micro- waves reflected from the cavity should, of course, be avoided. Fig. Variable attenuator Microwave EngineeringEfficiency of Reflex Klystron oscillator Lec-92 : https://youtu. be/BxzQSMlzqDQLec-93 : https://youtu. It includes a discussion of relations in. So, we have seen two-cavity klystron which is essentially an amplifier; we can have more than two cavities also. •The electron beam emitted from the cathode is accelerated by the grid and passes through the cavity anode to the repeller space between the Jul 31, 2018 · One major type is the reflex klystron, which is used primarily as an oscillator. In radar receivers. What modes are generally used in a reflex klystron? Ans. The electron beam is turned around by a negatively charged electrode that repels the beam. 7 and 5 (Figs. Due to the high negative field, the electrons repel back to the anode cavity. Thus the device used for amplifying microwave signals is known as Two-cavity Klystron. 12). Jensen Abstract This report deals with a method of modulating a reflex klystron whereby the message to be transmitted is modulated on a subcarrier, which in turn modulates the klystron through its repeller. An X-band klystron oscillator structure is assembled with a CNT cold A comprehensive analysis of reflex klystrons is developed by considering the electrons as particles acted upon by forces which modify their motion. reflex klystron amplifier | reflex klystron oscillator | reflex klystron animation | applegate OTHER TOPICS 1) Push pull amplifier https://youtu. Since there is no reflector, only one high-voltage supply is necessary to cause the tube to oscillate, the voltage must be adjusted to a particular value. It discusses how the reflex klystron works by using velocity modulation to transform an electron beam into microwave power using an anode cavity and repeller electrode. Both are feed-back oscillators, with one h. Lec 28: Limitations of Conventional Tubes at Microwave Ranges; Lec 29: Introduction to Klystron; Lec 30: Reflex Klystron, Magnetron and TWT; Ferrite devices. power, with a feed-back mechanism maintained by a constant retarding field. Figure 2-9. We know that British carefully planned all the developmental steps for their radar sets, including the use of microwaves when elsewhere the upper limit of usable frequencies was around 500 MHz. The main difference between two cavity reflex klystron amplifier and reflex klystron is that the output cavity is omitted in reflex klystron and the repeller or reflector electrode, placed a very short distance from the The factors governing the design of a reflex-klystron oscillator suitable for frequency modulation are discussed, and the conditions are considered which give maximum linearity between frequency and the modulating voltage applied to the reflector. To generate THE EQUIVALENT CIRCUIT OF A REFLEX KLYSTRON OSCILLATOR An equivalent circuit for a reflex-klystron oscillator based on the method outlined above, is shown in Fig. It describes how the electron beam is velocity modulated by the cavity gap voltage, with electrons accelerated or decelerated depending on the electric field. Of the resulting frequency spectrum only a narrow band, which A comprehensive analysis of reflex klystrons is developed by considering the electrons as particles acted upon by forces which modify their motion. The effect of the bunched electron beam is treated REFLEX KLYSTRON •Single Re-entrant cavity as a resonator. Reflex Klystron power supply. It is a single cavity device. be/tJuJ9XfR8OM This paper presents the design and fabrication of a reflex klystron oscillator based on a carbon nanotube (CNT) cold-cathode. xoelnjvtlpurgrrhofakowecrszsvwruwpkvmkueomywthxxc