There are several. IMO, the most likely to be successful is the "Bussard polywell" approach. A real nice "twist". It uses magnetic confinement to contain a cloud of electrons (due to low mass of electrons, they are FAR easier to magnetically contain) to create one electrode of an electrostatic confinement system (cf "Farnsworth Fusor"). Funded by the Navy and in "second round" (scaleup) of funding.
See "Talk-Polywell" for a forum that addresses this (and some other smaller efforts (Focus Fusion, and ever Rossi's LENR)).