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76 Cards in this Set
- Front
- Back
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Production of X-Rays
What is required for the production of X-Rays? -A source of _____________ -An appropriate _______________ -High _________ -A ______________ |
-electrons -target -voltage -vacuum |
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Parts of an X-Ray Tube
What are the parts of an X-Ray Tube? |
Cathode, anode, envelope and protective housing |
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What is the temp of a thermonic cloud? |
2200 degrees C |
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What are the parts of the Cathode Assembly? |
-Filament (s) -Focusing cup -wiring |
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Cathode Assembly
-Is the _____ side of the x-ray tube.
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-negative
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Filament 1. Thin coil of _____ ______ wire
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1. thoriated tungsten
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Filament
1. The _____ _____ ______ permits operation at the high temps of the xray tube.
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1. high melting point
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Filament
1. About _________ is required for thermionic emission (causes electrons to leve the filament surface and form a thermionic cloud)
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1. 2200 degrees C
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Vaporization
1. Results from the _____ not dirven to the anode or returned to the ______.
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1. electrons, filament
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Vaporization
1. Deposits can also cause increased ____ 2. Thus, tupe life can be greatly ______ 3. Vaporization can be decreased by addin 1-2% _____ to the tungsten 4. ______ lowers the amount of heat needed for thermionic emission. |
1. filtration 2. decreased 3. thorium 4. thorium |
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Filament Size
1. Size of the filament has a great effect on the ____ found in a radiograph 2. Smaller the filament and resulting focal spot, the ____________ the detail 3. Smaller filaments (and focal spots) are not able to handle the _____ ________ of greater milliamperage. |
1. detail 2. greater 3. heat requirements |
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Dual Filament Tubes
1. Most modern tubes have _____ filaments. 2. As filaments age they get ______ and are more subject to breakage. 3. Every second the rotor is held down, filament life is ____________ (Routinely delaying exposure and holding down the rotor can decrease tube life ___ to ___ % or 5,000 to 6,000 exposures) |
1. 2 2. thinner 3. decreased, 50-60%
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Filament
1. ____ _____ is sent to the filament when machine is turned on 2. _____ step of exposure sends a higher current to ______ to bring the thermionic cloud to the proper size for the mA selected. (this heating is what causes most of the vaporization) 3. Average tube life at "rotor" headting level is ___ to ____ hours or about 10,000 to 20,000 exposures. |
1. Mild current 2. Rotor, filament 3. 6-9 |
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Filament breakage
1. To increase filament life, two step exposure switches should be depressed in _____ _____. (Electonic locks will not permit exposure until the anode is at proper speed anyway.) 2. Single o exposure ready within ______ 3. 3 o and high frequency ready within _____ 4. Sometimes the situation demands that the rotor be _____ |
1. one motion 2. 10 msec 3. 1 msec 4. Held |
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The Focusing Cup
1. Cathode assembly contains a housing for the filament (s) called the ____ _____. 2. Usually made of Nickel, stainless steel, or _____ 3. The focusing cup has ____melting point and ____ thermionic emission 4. Electrons emitted from the filament are pulled across the tube to the positively charged ______. 5. There is a tendency for the like-charged electrons to _______ |
1. focusing cup 2. molybdenum 3. High, poor 4. anode 5. spread (electrons spread) |
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The Focusing Cup
1. The focusing cup ________ the elecrron stream due to its shape and low negative potential (small negative charge that is applied) 2. This focuses the electrons _______ one another 3. The charge applied is usually ________ as the filament charge. |
1. narrows 2. toward 3. the same |
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Biased Focusing Cup
1. The biased focusing cup has a voltage _____ than the filament potential 2. This creates a narrower _______stream. 3. Causes a smaller focual spot, and therefore more _______. 4. The biased focusing cup is common in ______. |
1. greater 2. electron 3. detail 4. mammography |
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Space Charge Effect
1. As electrons build up, they begin to ______ the emission of additional electrons. 2. This is called the _____ ______ ______. 3. Because of the space charge effect, most tubes are limited to a maximum mA ranges of _____ to ____. |
1. oppose 2. space charge effect 3. 1,000 to 1,2000 |
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Saturation Current
1. kVp is ______ 2. as kVp increases, a larger share of electrons are _______________________. 3. _______________ is the term for when all availabe electrons are attracted to the anode. 4. When saturation current is reached, the only way to increase tube mA is to _________________. 5. A __________________ chart demostrates this relationship. |
1. Potential diff 2. attracted to the anode 3. Saturation current 4. increase the filament current 5. filament emission chart |
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Grid-Based Tubes
1. Grid-Based tubes us a _____________ applied to the focusing cup, about 2,000 volts. 2. This attracts the electrons back to the _______. 3. __________ is pulsed in sync with the exposures to remove electrons from use. 4. Mult exposures in sequence. |
1. large voltage 2. focusing cup 3. high voltage |
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Grid-Based Tubes
1. Grid-based tubes allow short __________________ 2. They are useful for cine procedures, such as _____ and ______ 3. Grid-based tubes are also called __________ or ________. |
1. repeatable exposures 2. cath labs and angiography 3. grid-pulsed or grid controlled |
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The Anode Assembly
1. The anode is the ________ side of the x-ray tube. 2. The anode assembly refers to the ____, ____, and ____. |
1. positive 2. anode, stator and rotor |
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Anode Functions
1. The anode has how many functions. 2. Serves as ______ for the high-voltage electrons from the filament (source of the xray photons) 3. Conducts the _____________ from the cathode back into the x-ray circuit. 4. Serves as the ________________________ 5. The anode is also able to ______________. |
1. 3 2. target 3. high voltage 4. primary thermal conductor 5. conduct heat |
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Anode Construction
1. Stationary anodes are made from a tungsten-rhenium alloy at the _________________. 2. Rotating anodes are made from _____________ and are 5-13 cm in diameter. 3. Target tocal track is made from a ________________ alloy 4. tungsten is used for the target because of its ____________, __________ and its _______________ 5. Tungsten/charac xrays....binding entergy....69.5. |
1. end of a copper rod 2. molybdenum 3. tungsten-rhenium 4. high melting point, heat conducting ability and its high atomic number, which is 74 |
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Anode Construction
1. Anodes can be ______ or _________. 2. Rotating anodes _________ during exposure, creating a much larger target area 3. The faster the target turns, the better the heat ________ 4. Stationary anodes are found in low power situations, such as _______________ |
1. stationary or rotating 2. turn 3. dissipation 4. dental x-rays |
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Anode Construction 1. Rhenium is used to increase the _____ of the target and to help handle the temp changes. 2. Some anodes have a __________ or __________ whell behind the disc to increase the ability to handle heat. |
1. elasticity 2. graphite or molybdenum |
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Anode construction
1. Mammography tubes will have a _______________ target (atomic number ____) 2. Enables tube to produce more ______________ characteristic photons. 3. In addition, these tubes have a special _____________ to allow the low energy photons to pass. |
1. molybdenum, 42 2. low energy 3. beryllium window |
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Anode Wear
1. Normal use will vaporize the target material, creating a ___________ surface, reductin tube efficiency. 2. Warm up procedure helps prevent _____________. 3. Typical warm up procedure is around _______ at 200 mA for 1 second (basis) 4. ___________ dissipate heat more efficiently and do not require warm-up procedures. |
1. rough, pitted 2. cracking the anode 3. 70 kVp 4. stress relieved anodes |
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The Target Area
1. The point where the electrons strike is called the _____, the _____, the _____, the ______ or the ______. 2. Focal track refers to the _______________ path that the xrays will strike 3. The other terms refer to the ____________. |
1. target, the focus, the focal point, the focal spot or the focal track 2. circular 3. point of impact |
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The Target Area
1. It is from this point (point of impact) the ____ is measures. (The zero point of the measuring device) 2. ____________ refers to the physical point that the electrons strike. 3. _________ describes the area of the focal spot that is projected out of the tube toward the object being radiated. |
1. SID 2. Actual focal spot 3. effective focal spot |
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The Line-Focus Principle
1. the line focus principle is used to ______ the effective area of the __________. 2. This allows the thermal characteristics of a large focal spot while permitting the _______________. 3. Effective focal spot is controlled by the size of the actual focal spot (controlled by the filament size) and by the ______________. |
1. reduce, focal spot 2. detail of a smaller focal spot 3. anode target angle |
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The Line-Focus Principle
1. As the actual focal spot size increases, effective focal spot size ____. 2. When the anode angle is less than 45 degrees, the effective focal spot is _______ than the actual focal spot. 3. As the angle decreases, effective focal spot size ________. |
1. increases 2. smaller 3. decreases |
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The Line-Focus Principle
1. A smaller effective focal spot results in more _____ 2. Tubes are availabe with anode angles of ___ to ____, with ____ being most common. 3. A smaller focal spot limits the field of coverage: it takes a 12" anode angle to cover a ___________field at 40". |
1. detail 2. 7 to 17, 12 3. 14"x17"
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The Line-Focus Principle
1. The line focus principle applies only in the ____________. 2. The horizontal size of the focal spot must be _________. Usually less than ____. 3. The focal spot size (the vertical dimension) that is listed on the control panel is the ____________. 4. A focal spot size that is less than 1 mm can be called a _____________. |
1. directions of the angle 2. narrow, 2mm 3. effective focal spot size 4. fractional focal spot size |
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The Line-Focus Principle
1. Most tubes have dual ___________. One for ______ and One for _______ 2. Focal spot size may be mandated by the ____. (small focal spot- low ____) 3. Focal spot size increases or blooms as mA is increased but, no resounding effect on ______. |
1. focal spots, detail, heavy tube loads 2. mA, mA 3. detail
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The Anode Heel Effect
1. The anode heel effect is the result of the _____. 2. Because of the geometry of the anode angle, radiation intensity is ______ on the cathode side of the tube. 3. As xrays are produced at the target, most are emitted between 45 degrees and 90 degrees in the direction the _____ travel. These are absorbed by the ______ or the tube housing. 4. FAT CAT |
1. line-focus principle 2. cathode 3. electron, anode |
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The Stator
1. The Stator is the only part of the cathode or anode assemblies that is outside the ________ 2. It is an induction motor consisting of electro-magnets (coils of wire) that turn the _____ 3. Electromagnets would be _______by the tubes kilovoltage if inside 4. When the tube is ___ current is sent ot the stator, which causes the rotor to turn. 5. If the stator fails, the anode will not spin, and will ______ |
1. glass envelope 2. rotor 3. destroyed 4. rotored 5. melt |
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The Rotor 1. Rotor is inside the glass envelope, which is inside the ---- 2. Made of a hollow copper cylinder that is attached to the anode disk by a ____ 3. Inside the rotor contains silver plated steel ____ |
1. stator 2. molybdenum shaft 3. ball bearings |
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The Rotor
1. The rotor is the ____ you hear when you rotor the tube in the shaft turning inside ball bearings 2. If rotates for less than ____ seconds when the exposure is finished, the bearings are near binding. 3. Rotating anodes spin at about_____ 4. High speed anodes spin at ______ |
1. noise 2. 20 3. 3,200-3,600 4. 10,000-12,000 |
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The rotor
1. High speed anodes produce possible _____ harmonics between 5000-7000 rpm. 2. A ______ applied to the stator quickly slows the rotor at the end of the exposure. 3. Another problem involves the anodes ______ effect 4. Moving the tube housing while the anod is spinning can cause trauma to the disk and bearings. Thus extremely fast tube movement should be ______. |
1. glass shattering 2. direct current 3. gyroscopic effect 4. avoided |
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The Rotor
1. A common cause of tube failure is _______ 2. As bearings ear the rotor begins to wobble and cause a loss in _____ 3. Another effect of bad stator/rotor is that the target area gets _____. The superheated tungsten can melt into the glass envelope and ______ 4. If cracked envelope developes, oil can cause an explosion or leak onto the patient. If you see oil leaking ________ |
1. bad bearings 2. efficiency 3. overheated, destroy the tube 4. Move the patient |
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The Envelope
1. Commonly made of pyres glass or _____, which is sealed to maintain a ____. Metal is becoming more common because they prolong tube life. 2. Primary bean exits the tube at a _____ or ____, which is sometimes thinner than the rest of the tube. This results in less absorption of the ______ 3. Mammography tube will have a ________ window to avoid attenuating lower energy photons. |
1. metal, vacuum 2. window, port, primary beam 3. beryllium
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The Envelope
1. Primary function of the envelope is to provide a ______ 2. Removal of air permits electrons to flow from cathode to anode without encountering the gas atoms of air, thus, increasing tube ___ |
1. vacuum 2. efficiency
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The protective housing
1. Protective housing controls leakage and scatter radiation, isolates the high volages and _________ 2. When x-rays are produced in the anode they are emitted ________ 3. The _____ exists the window, and the housing absorbs much of the rest of them. |
1. provides a means to cool the tube 2. isotropically (in all directions) 3. primary beam |
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The Protective Housing
1. The housing is made of _______ 2. It is lined with ____ at the cathode end because of the direction of the photon emission. 3. Photons that escape from the housing except at the port (window) are termed ___________ 4. LEAKAGE RADIATION MUST NOT EXCEED ______ 5. The housing also serves as a cushion for the ______ |
1. cast steel 2. lead 3. leakage radiation 4. 100 mR/hr at 1 meter 5. tube |
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Off-focus Radiation
1. Off-focus or extrafocal radiation is composed of ______ that were not produced at the focal spot. 2. When high speed electrons hit the focal spot, they can create scattered electrons or radiation that will create more x=rays when they strike another object in the tube and _________ 3. The tube housing absorbs most of these photons but those that are at the proper direction and angle _____________ |
1. photons 2. produce photons 3.will exit the tube window |
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Off focus radiation
1. When photons exit the tube window it causes ________ of structures adjacent to the edge. 2. This is frequently mistaken for ________ 3. However, scatter cannot create a ________ |
1. ghosting 2. scatter 3. diagnostic image |
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Rating Charts and Cooling Curves
1. What are the 3 types of charts available to radiographers to help prevent damage to the tube? |
1. tube rating charts, anode cooling charts, and housing cooling charts |
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Tube Rating Charts
1. Tube rating charts provide a guide for the ______ technical factors that may be used without overloading the tube, mA, kV and time are plotted. 2. Each tube and filament have a separate _____ |
1. maximum 2. chart |
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Anode Cooling Charts
1. Anode cooling charts permit the calculation of the ______ necessary for the anode to cool enough for additional exposures to be made. 2. All cooling charts are calculated in terms of ________ |
1. time 2. heat units |
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Heat Units
1. A heat unit is calculated by ______ 2. Rectification constants_______ |
1. kVp x mA x time x constant (rectification constant) 2. single phase (full wave) = 1.00 3 phase = 1.35 high frequency = 1.45 |
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Housing Cooling Charts
1. Housing cooling charts permit the calculation of the time necessary for the housing to _____ enough for additional exposures to be made. 2. They are similiar to _______cooling charts 3. May be useful when the forced air fan is not ______ |
1. cool 2. anode 3. functioning |
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Extending Tube Life
1. Use proper ________ procedures
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1. warm up |
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Extending Tube Life
1. No unnecessary ______
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1. rotoring |
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Extending Tube Life
1. Use low _____ stations when possible.
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1. mA |
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Extending Tube Life
1. Use ______ speed rotor if possible
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1. lower
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Extending Tube Life
1. Do not make repeated exposures near the tube _______ |
1. loading limits
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Extending Tube Life
1. Do not rotate the tube housing _______
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1. housing rapidly
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Extending Tube Life
1. Do not use the tube when you can hear ______ |
1. loud rotor bearings |
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Cathode Assembly
-Produces a ________ _______ to serve as a source of electrons |
thermionic cloud |
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Cathode Assembly
-Conducts the high voltage to the gap between the ______ and the _____ |
cathode and anode |
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Cathode Assembly
-Focuses the _______ _______
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electron stream |
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Cathode Assembly
-Producing ___________ (neg) |
electrons |
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Filament
1. 0.1-0.2 mm thick, 1-2 mm wide, by _____ mm long
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1. 7-15 mm |
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Filament
1. Set within the _____ _____ |
1. focusing cup |
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Filament
1. Tungsten is used because of its _____________ and because it's difficult to _________ |
1. high melting point, vaporize |
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Filament
1. Rhenium (3,170 C) and ___________ are also used (adds to it) |
1. molybdenum (2,620 C) (mammo) |
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Filament
1. The _____ and ______ of the wire permit more resistance to electrical current, which effects the ability of the xray tube to image fine details. |
1. length and width |
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Filament
1. Most tubes have a _____ _____ arrangement (2 filaments) |
1. dual focus |
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Filament
1. Shorter wire = ______ ______ |
1. more detail |
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Filament
1. The entire cloud is driven toward the _____ ____ when the high voltage is released at exposure. |
1. anode target |
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Filament
1. High temp required for thermionic emission would ______ many substances of this size. |
1. vaporize |
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Vaporization
1. This contributes to reducing the _____, thus making the tube _____
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1. vacuum, gassy |
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Vaporization
1. This vaporized tungsten also depostis on the _______ ______ of the glass envelope. (old tubes may appear ______) |
1. glass envelope, mirrored |
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Vaporization
1. This can eventually cause ____ (when sufficient current is attracted to the deposit during an exposure)
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1. arcing |
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Vaporization
1. Arcing -> _______ |
1. blown |
