  The ALICE experiment at the Large Hadron Collider (LHC) proposes major
detector upgrades to fully exploit the increase of the luminosity of the LHC in
RUN~3 and to extend the physics reach for rare probes at low transverse
momentum. The Time Projection Chamber (TPC) is one of the main tracking and PID
devices in the central barrel of ALICE. The maximum trigger rate of the TPC is
currently limited to about 3.5 kHz by the operation of a gating grid system. In
order to make full use of the luminosity in RUN 3, the TPC is foreseen to be
operated in an ungated mode with continuous readout. The existing MWPC readout
will be replaced by a Micro-Pattern Gaseous Detector (MPGD) based readout,
which provides intrinsic ion capture capability without gating. Extensive
detector R\&D employing Gas Electron Multiplier (GEM) and Micro-Mesh Gaseous
detector (Micromegas) technologies, and simulation studies to advance the
techniques for the corrections of space-charge distortions have been performed
since 2012. In this paper, the expected detector performance and the status of
the R\&D program to achieve this ambitious goal are described.
