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What Are the Basic Components of SEM?

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There are four basic components of SEM:

1. Search engine marketing (SEM) is the process of marketing a website through the use of search engine optimization (SEO) and pay-per-click (PPC) advertising.
2. SEO is the process of optimizing a website for Google’s search algorithm in order to rank higher in Google’s search results.
3. PPC advertising is a form of online advertising in which advertisers bid on keywords that are relevant to their business and pay when their ad is clicked by a user.
4. Social media marketing (SMM) is the process of promoting a website or product through social media channels such as Facebook, Twitter, and LinkedIn.

Electron Source. Tungsten (W) electron filament. Lanthanum hex abo ride (LaB6) or Cerium hex abo ride (CeB6) Field Emission Gun (FEG)

An electron source is a device that generates electrons. The three most common types of electron sources are tungsten (W) filament, lanthanum hex abo ride (LaB6), and cerium hex abo ride (CeB6). Each type of electron source has its own advantages and disadvantages.

Tungsten Filament Electron Source

The most common type of electron source is the tungsten filament. Tungsten filaments are made of a thin wire of tungsten metal that is heated to high temperatures, typically between 2000-3000 degrees Celsius. When heated to these temperatures, the tungsten wire emits electrons due to thermionic emission. Thermionic emission occurs when electrons are emitted from a hot metal surface due to the metal’s high thermal energy.

One advantage of using a tungsten filament as an electron source is that it can be easily turned on and off. Since the filament only needs to be heated to high temperatures for a short period of time in order to emit electrons, it can be quickly turned on and off as needed. This makes the tungsten filament an ideal choice for applications where frequent start/stop cycles are required, such as in X-ray tubes used for medical imaging. Additionally, tungsten filaments are relatively inexpensive compared to other types of electron sources. However, one disadvantage of using a tungsten filament is that it has a relatively short lifetime due to its fragile nature; after approximately 1500 hours of use, the filament will need to be replaced. Additionally, the high temperatures required for operation can cause problems with heat dissipation and thermal stress on surrounding components if not properly designed for cooling purposes.


The electron source is usually an electron gun that emits a beam of electrons that is focused by the lenses on to the sample. The detector measures the number of electrons that are scattered from the sample and produces an image based on this information.

The lenses in a SEM system play a critical role in determining how well the system performs. There are two types of lenses used in SEM systems: electrostatic lenses and magnetic lenses. Electrostatic lenses use electric fields to focus the electron beam, while magnetic lenses use magnetic fields. Both types of lens have their own advantages and disadvantages.

Electrostatic lenses are typically cheaper to manufacture than magnetic lenses and can be made with greater accuracy. However, they tend to produce images with lower contrast and resolution than magnetic lenses. Magnetic lens tend to be more expensive but can provide better images with higher contrast and resolution.

Scanning Coil

Scanning coils are used in a variety of applications, including medical imaging, security screening, and quality control inspection. In medical imaging, scanning coils are used to create magnetic fields that can be used to obtain images of internal organs and tissues. In security screening, scanning coils are used to detect metal objects hidden under clothing or inside baggage. In quality control inspection, scanning coils are used to detect defects in manufactured products.

The operation of a scanning coil is based on the principle of electromagnetic induction. When an electric current is passed through the coil, it creates a magnetic field. This magnetic field can then be used to interact with objects in its vicinity. For example, when a scan.

Sample Chamber

Most commercial SEMs have a cylindrical chamber with a flat bottom. The sample is placed on a stage in the center of the chamber and held in place by clamps or vacuum suction. The stage can be moved in X-Y directions so that different areas of the sample can be scanned. In some cases, it may also be possible to tilt the stage to obtain oblique views of features on the surface of the sample.

The walls of the SEM chamber are usually made of metal, although some instruments use glass or other materials that do not block electron beams. To allow for electrical insulation, most chambers have an inner liner made of an insulating material such as quartz or ceramic. This liner protects against electrical breakdown when high voltages are applied to elements inside the SEM chamber, such as when electrons are accelerated to high energies in order to create X-rays.


Jeremy is a SEO and web traffic specialist with years of experience in lead generation, sales, copywriting, and conversion optimization. He has helped countless businesses grow their online presence and increase their sales. His passion is helping businesses succeed online and he is always looking for new ways to improve his craft. He loves sharing his experience through articles and videos to help people achieve their marketing and sales goals.