Small Scale Tokamak for X-Ray Lithography

A toroidal plasma device (tokamak) with electron temperature in the range of 150-200 eV and density ~1013 particles/cm3 can be built as a very compact and relatively inexpensive machine (~3 M$). A tokamak with a major radius R ≈ 1m, minor radius r ≈ 0.1m, and confining magnetic field ~ 5k Gauss is not a very attractive for fusion research, however it can be an excellent source of soft X-ray radiation. In particular if operated in a steady state regime or at a high repetition rate it can provide several orders of magnitude more soft X-ray radiation than a small synchrotron with an undulator. This can be seen easily by comparing the total radiated power of a small tokamak and a small sychrotron, taking into account the spectral intensity distribution of line radiation from the tokamak plasma and of continuum radiation from synchrotron. We will present related calculations. Based on the calculations we will discuss the usefulness of a small tokamak for X-ray projection and proximity lithography and simple methods to change the dominant lines in the plasma radiation spectrum.