Insertion time

Insertion time

The term insertion time is used to describe the length of time which is required to rearrange a subcritical mass of fissile material into a critical mass. This is one of the three main requirements in a nuclear weapon design to create a working fission atomic bomb. The need for a short insertion time with plutonium is the reason why the implosion method was chosen for the first plutonium bomb, while with uranium-235 it is possible to use a gun design.

The basic requirements are:
* To start with a subcritical system
* To create a super prompt critical system
* To make the change between these two states in a length of time (insertion time) which is shorter than the time between the random appearance of a neutron in the fissile material through spontaneous fission or by other random processes.
* Also at the right moment in time, neutrons must be injected into the fissile material to start up the fission process. This can be done by several methods.
** Alpha emitters such as polonium or plutonium-238 can be rapidly combined with beryllium to create a neutron source.
** Boosted fission weapon where a D-T reaction is caused by the heating of the implosion. This creates the neutrons required for the start up of the device.
** Neutrons can be generated using an electrostatic discharge tube, this tube uses the D-T reaction.


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Insertion sort — Infobox Algorithm class=Sorting algorithm data=Array time= О(n²) space= О(n) total, O(1) auxiliary optimal=Not usuallyInsertion sort is a simple sorting algorithm, a comparison sort in which the sorted array (or list) is built one entry at a time …   Wikipedia

  • Time complexity — In computer science, the time complexity of an algorithm quantifies the amount of time taken by an algorithm to run as a function of the size of the input to the problem. The time complexity of an algorithm is commonly expressed using big O… …   Wikipedia

  • Repeater insertion — is a technique for reducing the time delay associated with long wire lines in integrated circuits. The technique involves cutting the long wire into one or more short wires and inserting a repeater between each new pair of short wires.The time it …   Wikipedia

  • Orbit insertion — is the spaceflight operation of adjusting a spacecraft’s momentum to allow for entry into a stable orbit around a planet, moon, or other celestial body.[1] This maneuver involves either deceleration from a speed in excess of the respective body’s …   Wikipedia

  • Dynamic time warping — Not to be confused with the Time Warp mechanism for discrete event simulation, or the Time Warp Operating System that used this mechanism. Dynamic time warping (DTW) is an algorithm for measuring similarity between two sequences which may vary in …   Wikipedia

  • Zero insertion force — [ socket A)] ZIF is an acronym for zero insertion force, a concept used in the design of IC sockets, invented to avoid problems caused by applying force upon insertion and extraction.A normal integrated circuit (IC) socket requires the IC to be… …   Wikipedia

  • Local insertion — In broadcasting, local insertion is the act or capability of a broadcast television station, radio station, or cable TV system to insert or replace part of a broadcast network feed with content unique to the local station or system. Most often… …   Wikipedia

  • Julia Duffy (Axis of Time) — In John Birmingham s Axis of Time trilogy, Julia Duffy is a New York Times reporter who was born on July 20, 1989, Pre Transition Timeline. She was embedded with the 82nd Marine Expeditionary Unit when the UNPROFLEETwas caught in a temporal… …   Wikipedia

  • Coordinated Universal Time — UTC redirects here. For other uses, see UTC (disambiguation). Coordinated Universal Time (abbreviated UTC) is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich… …   Wikipedia

  • Real-time operating system — A real time operating system (RTOS; generally pronounced as are toss ) is a multitasking operating system intended for real time applications. Such applications include embedded systems (programmable thermostats, household appliance controllers,… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”