Lêmanên Xeon: Çavkaniyek Nûrî Peyvên û Pêşeng
A xenon arc lamp tîpêk bir yis dişargi lampasê ye ku ji bo çikirina nûre bi serdanelek da biborin di nav ionized xenon gas de bi presyasyonê ya bikuhet. Xenon arc lamps hewceyên derketina tevahiyên ultraviolet ve tevahiyên derketinên binihûr in, bi dalên xusiyên çikirin di nav 750 der 1000 nm de. Wan nûra binihûr e çikirin ku bi şîn rojekî werçînin, ku vebijarkên wan di her sahên de an jî pêşdestan, wek film, simulation roja, testkirina civî, û li ser pirsgire. Xenon arc lamps bi sê kategorîyan dabejin: continuous-output xenon short-arc lamps, continuous-output xenon long-arc lamps, û xenon flash lamps.
What is a Xenon Arc Lamp?
Xenon arc lamp taybetmend tîpêk yis dişargi lampasê ye, çikirina nûre bi serdanelek da biborin di nav xenon gas de bi presyasyonê ya bikuhet. Term "arc" referand e electric current e ku di nav divêran ên gas-filled tube de çavkerde. Term "xenon" referand e tenê gas ku bi sergasîna yekî yên gas mixture da bikar înin. Xenon ji bo numrayên atomî ya bilind û ionization potential ên kêmtir hewce dikin ku nûra broad spectrum da biborin bi intensity û color rendering ên bikuhet.
How Does a Xenon Arc Lamp Work?
Strukturê bingehîn a xenon arc lamp du thoriated tungsten electrodes ne ku bi serbexsherî di nav gap ên qeyser an airtight transparent envelope of fused silica (ji we ku quartz) de. Thoriated tungsten tîpêk tungsten alloy e ku 1 der 2% thorium hat zêde kirin bi tenê electron emission capability ên tungsten hilaz bike. Fused silica noncrystalline transparent silicon dioxide glass e ku extra strength û almost zero thermal expansion dibide. Ew high pressure û high temperature dibeşdar e.
Envelope û bulb bi xenon gas de re bi presyasyonê ya bikuhet, bînavber 30 bars. Di demê da voltage applied across the electrodes, gas discharge phenomenon starts in the xenon gas in the gap between electrodes. There are always some free electrons in the gas due to thermal agitation or cosmic rays. Due to the applied electric field across the electrodes, the free electrons get accelerated and collide with xenon atoms. Due to these collisions, electrons from the outer orbit of the xenon atoms get detached from their position and come to a higher energy level. Atoms with electrons of higher energy levels are called excited atoms.
When the excited atoms return from their higher energy level to their previous energy state, they release the extra energy as photons. The wavelength of energy emitted by photons is within the visible range. The color of the light of the xenon arc lamp is like daylight. Due to the electrostatic attraction of the anode (positive electrode), the free electrons ultimately come to the anode and return to the source.
Due to the attraction of the cathode (negative electrode), the positive ions (xenon atoms that lost electrons) ultimately collide with the cathode’s front surface and generate positive metal ions, neutral xenon atoms, and free electrons. These electrons are called secondary emitted electrons. These electrons help to continue the gas discharge process.
As the cathode is not additionally heated for electron emission, the cathode of a xenon arc lamp is known as a cold cathode.
What are the Types of Xenon Arc Lamps?
Xenon arc lamps can be roughly divided into three categories: continuous-output xenon short-arc lamps, continuous-output xenon long-arc lamps, and xenon flash lamps.
Continuous-output Xenon Short-arc Lamps
Continuous-output xenon short-arc lamps are designed for direct current (DC) operation with a very short arc length (typically less than 5 mm). They have high luminous efficacy (up to 75 lumens per watt) and high color rendering index (up to 95). They are widely used for cinema projection, searchlights, solar simulators, and other applications that require high brightness and stability.
Continuous-output Xenon Long-arc Lamps
Continuous-output xenon long-arc lamps are designed for alternating current (AC) operation with a longer arc length (typically more than 10 mm). They have lower luminous efficacy (up to 40 lumens per watt) and lower color rendering index (up to 85) than short-arc lamps. They are mainly used for general lighting purposes, such as street lighting, industrial lighting, and architectural lighting.
Xenon Flash Lamps
Xenon flash lamps are designed for pulsed operation with a very high peak power (up to several megawatts) and a very short duration (typically less than 1 millisecond). They have low average power consumption (up to 10 watts) and low average luminous efficacy (up to 10 lumens per watt). They are mainly used for photographic flash, strobe lights, laser pumping, and other applications that require high intensity and short duration.
What are the Advantages of Xenon Arc Lamps?
Xenon arc lamps have several advantages over other types of light sources:
• They produce a broad spectrum of light that covers most of the visible range and some of the ultraviolet and infrared range. • They have a high color rendering index that makes objects appear more natural and vivid. • They have a high color temperature that simulates natural sunlight and enhances visibility. • They have a long lifetime that ranges from 500 hours (7 kW) to 1500 hours (1 kW). • They have a stable arc with less flicker and noise. • They have non-consumable electrodes that allow longer operation without interruptions. • They have a low environmental impact as they do not contain mercury or other toxic substances.
What are the Disadvantages of Xenon Arc Lamps?
Xenon arc lamps also have some disadvantages compared to other types of light sources:
• They require high voltage and current to operate, which increases the cost and complexity of power supply and control systems. • They generate a lot of heat that requires efficient cooling systems. • They emit ultraviolet radiation that can cause eye damage or skin cancer if not properly filtered or shielded. • They are sensitive to shock and vibration that can damage or break the glass envelope or electrodes. • They are expensive to purchase and maintain compared to other types of light sources.
