page_title: Pinch (plasma physics)
section_title: Types
hierarchical_section_title: Pinch (plasma physics) / Types
caption_attribution_description: en:Z-pinches constrain the plasma filaments in an en:electrical discharge from a en:Tesla coil. Photo taken by Ian Tresman at the UK Teslathon in Derby, UK, on 27 May 2005.
context_page_description: A pinch is the compression of an electrically conducting filament by magnetic forces. The conductor is usually a plasma, but could also be a solid or liquid metal. Pinches were the first type of device used for controlled nuclear fusion.
  The phenomenon may also be referred to as a Bennett pinch, electromagnetic pinch, magnetic pinch, pinch effect or plasma pinch.
  Pinches occur naturally in electrical discharges such as lightning bolts, the aurora, current sheets, and solar flares.
context_section_description: Pinches exist in laboratories and in nature.  Pinches differ in their geometry and operating forces.  These include:
  Uncontrolled
  Any time an electric current moves in large amounts (e.g., lightning, arcs, sparks, discharges) a magnetic force can pull together plasma.  This can be insufficient for fusion.
  Sheet pinch
  An astrophysical effect, this arises from vast sheets of charge particles.
  Z-pinch
  The current runs down the axis (or walls) of the cylinder while the magnetic field is azimuthal
  Theta pinch
  The magnetic field runs down the axis of the cylinder, while the electric field is in the azimuthal direction (also called a thetatron)
  Screw pinch
  A combination of a Z-pinch and theta pinch  (also called a stabilized Z-pinch, or θ-Z pinch)
  Reversed field pinch
  This is an attempt to do a Z-pinch inside an endless loop.  The plasma has an internal magnetic field. As you move out from the center of this ring, the magnetic field reverses direction.  Also called a toroidal pinch.
  Inverse pinch
  An early fusion concept, this device consisted of a rod surrounded by plasma.  Current traveled through the plasma and returned along the center rod.  This geometry was slightly different than a z-pinch in that the conductor was in the center, not the sides.
  Cylindrical pinch
  Orthogonal pinch effect
  Ware pinch
  A pinch that happens inside Tokamaks.  This is when particles inside the Banana orbit condense together.
  MagLIF
  A Z-pinch of pre-heated, pre-magnetized fuel inside a metal liner, which could lead to ignition and practical fusion energy with a larger pulsed-power driver.
caption: An example of a man-made pinch.  Here Z-pinches constrain the plasma inside filaments of electrical discharge from a Tesla coil
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