Browse Definitions:
Definition

nuclear fusion

Contributor(s): Robert Lidral

Nuclear fusion is an atomic reaction in which multiple atom s combine to create a single, more massive atom. The resulting atom has a slightly smaller mass than the sum of the masses of the original atoms. The difference in mass is released in the form of energy during the reaction, according to the Einstein formula E = mc 2 , where E is the energy in joule s, m is the mass difference in kilogram s, and c is the speed of light (approximately 300,000,000 or 3 x 10 8 meters per second).

The most common nuclear fusion reaction in the universe, and the one of most interest to scientists, is the merging of hydrogen nuclei to form helium nuclei. This is the process that occurs in the interiors of stars including the sun. Hydrogen fusion is responsible for the enormous energy output that stars produce. The reaction involves three steps. First, two proton s combine to form a deuterium nucleus, which consists of one proton and one neutron . A positron (also called an anti-electron) and a neutrino (a particle with negligible mass but extreme penetrating power) are generated during this part of the process. Second, the deuterium nucleus combines with another proton, forming a nucleus of helium 3, which consists of two protons and one neutron. An energetic photon is produced during this part of the process, with a wavelength in the gamma-ray portion of the electromagnetic spectrum . Finally, two nuclei of helium 3 combine to form a nucleus of helium 4, which consists of two protons and two neutrons. In this part of the process, two protons (ordinary hydrogen nuclei) are released. These protons can eventually become involved in another fusion reaction.

Nuclear fusion requires extremely high temperatures, on the order of tens of millions of degrees Celsius . In addition, an intense attractive force, such as gravitation of the magnitude that occurs in the centers of stars, is necessary to overcome the electrostatic repulsion among positively charged nuclei. Scientists can generate the high temperatures and forces required to produce uncontrolled hydrogen fusion, the most notable example being the hydrogen bomb. However, sustaining these temperatures and forces indefinitely, in order to construct a hydrogen fusion reactor that can generate useful energy, has proven difficult. Research in this direction took a significant step forward in June 2005, with the announcement of an experimental fusion reactor to be built in the south of France.

This was last updated in July 2005

Start the conversation

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.

-ADS BY GOOGLE

File Extensions and File Formats

Powered by:

SearchCompliance

SearchSecurity

  • password

    A password is an unspaced sequence of characters used to determine that a computer user requesting access to a computer system is...

  • adware

    Adware is any software application in which advertising banners are displayed while a program is running.

  • botnet

    A botnet is a collection of internet-connected devices, which may include PCs, servers, mobile devices and internet of things ...

SearchHealthIT

SearchDisasterRecovery

  • call tree

    A call tree -- sometimes referred to as a phone tree -- is a telecommunications chain for notifying specific individuals of an ...

  • mass notification system (MNS)

    A mass notification system is a platform that sends one-way messages to inform employees and the public of an emergency.

  • disaster recovery as a service (DRaaS)

    One approach to a strong disaster recovery plan is DRaaS, where companies offload data replication and restoration ...

SearchStorage

  • data migration

    Data migration is the process of transferring data between data storage systems, data formats or computer systems.

  • compact disc (CD)

    A compact disc is a portable storage medium that can be used for recording, storing and playing back audio, video and other data ...

  • secondary storage

    Secondary storage is used to protect inactive data written from a primary storage array to a nonvolatile tier of disk, flash or ...

SearchSolidStateStorage

  • SSD RAID (solid-state drive RAID)

    SSD RAID (solid-state drive RAID) is a methodology commonly used to protect data by distributing redundant data blocks across ...

  • Tier 0

    Tier 0 (tier zero) is a level of data storage that is faster, and perhaps more expensive, than any other level in the storage ...

  • PCIe SSD (PCIe solid-state drive)

    A PCIe SSD (PCIe solid-state drive) is a high-speed expansion card that attaches a computer to its peripherals.

SearchCloudStorage

  • RESTful API

    A RESTful application program interface breaks down a transaction to create a series of small modules, each of which addresses an...

  • cloud storage infrastructure

    Cloud storage infrastructure is the hardware and software framework that supports the computing requirements of a private or ...

  • Zadara VPSA and ZIOS

    Zadara Storage provides block, file or object storage with varying levels of compute and capacity through its ZIOS and VPSA ...

Close