Integrated "plastic" fabrication

Background

If ultra light space flight is the smallest possible craft on the smallest possible budgets, then ultra light design budgets require ultra light fabrication.

Any combination of fabrication and construction techniques imply a minimal scale of design budget. We can imagine integrated fabrication and construction via advanced "rapid prototyping" style techniques. Integrated fabrication and construction is building components and structures in mixed materials in one extended process. The potential is to lower design scale, and to raise reproducibility.

Example

In the design case for cryogenic hydrogen and oxygen rocket propulsion, component operating temperatures have a maximal range. An ideal design material would be cubic carbon. Researchers have reported the composition of cubic carbon at low pressure and temperature by ionic techniques to produce films. The reported growth or build advance rates are very slow. Open problems include building structure (not film), and at a practical rate. Practical integrated fabrication with cubic carbon would offer solutions for many critical design problems.

Process models

Integrated construction processes can be imagined in a couple models.

Attractive in terms of build rate is the raster model. Arbitrary scan lines are deposited serially, switching materials with frequency and fidelity -- as a television or computer screen is drawn in its horizontal scan lines by switching colors in each pixel. This approach is not expected to be a probable path to success because some materials may not adapt to rasterization. For example, modes of graphene -- "chairs" and "stairs" -- are dependent on subtleties of edge formation. It would seem to be the least probable case that ionic composition processes would be flexible enough to accommodate such subtleties under the maximal constraints of arbitrary rasterization.

An alternative build process model is the tool centric one. This is analogous to the material centric build process model.

Material model

The alternative to the raster model is an ad hoc one, a build process that follows material parameters. Naturally, build ordering would have automated routing like a raster or tool model. However, the first principle is material over process. Rasterization may be possible for many materials, but material switching may be far more advanced than necessary.

Parametric Composition

The integrated fabrication process needs to automatically switch materials according to a parametric recipe for the construction of a component or system of components.

The statement imagines materials including carbon, silicon, silver, boron, and perhaps tungsten, nickel, platinum or titanium.

Materials begin with the production of streams of ions. The reliable production of streams of ions of known size and charge is important to the remainder of the parametric composition process. A stream of ions can be filtered for mass by an electric field, and directed and accelerated by a magnetic field.

The composition parameters would be ion mass and charge, and stream density and flux.

Determination of Parameters

The constraint on an exhaustive search through this parameter space is in the determination of the result of a set of parameter values.

Therefore sensing or detecting the activity or result at the composition target has two related critical figures in time and space. In one possible ideal, a visual resolution of tens of picometers is instantaneous. In such a case we could afford a relatively care free search through the composition parameter space.

An actual exhaustive search would be prohibitive -- excepting parallelism. Alternatives to exhaustive search include parametric guidance from literature, intuition, or chemical or quantum simulation. The search space will be nonlinear, so intuition will be rare.

Reducing Space

The initial conception of target detection is visual because it covers a variety of characteristics. However, if a parameter space could be reduced through the detection of particles of increased mass produced by particular kinds of processes then this search process may be faster and automatable.

Additional conceptions of process space for parameter search may be directed by simulation or other information.