The non-traditional machining process that essentially requires vacuum is Electron Beam Machining (EBM).

Explanation:
Electron Beam Machining (EBM) is a non-traditional machining process that utilizes a high-velocity electron beam to remove material from a workpiece. This process requires a vacuum environment to operate effectively. Here is a detailed explanation of why EBM requires a vacuum:

1. Principle of Electron Beam Machining:
EBM is based on the principle of thermoelectric energy conversion. A high-velocity electron beam is generated by accelerating electrons using high voltage. These electrons have high kinetic energy, which is converted to thermal energy upon collision with the workpiece. The intense heat generated by the electron beam melts and vaporizes the material, resulting in material removal.

2. Need for Vacuum Environment:
The vacuum environment is crucial in EBM due to the following reasons:

- Prevention of Electron Scattering: In a vacuum, there are no gas molecules to scatter the electron beam. Scattering can cause deviation of the beam and reduce its intensity, leading to less precise machining. By eliminating the gas molecules, the electron beam can maintain its focus and accuracy.

- Prevention of Oxidation and Contamination: Many materials, especially metals, are susceptible to oxidation and contamination when exposed to air. The vacuum environment in EBM prevents the workpiece from reacting with oxygen or other gases, preserving the material's integrity and ensuring high-quality machining.

- Efficient Electron Generation: The vacuum environment helps in generating high-velocity electrons efficiently. In a vacuum, there is less resistance for electron acceleration, allowing for higher speeds and energies. This results in a more powerful electron beam, capable of effectively removing material from the workpiece.

3. Practical Implementation:
In EBM, a vacuum chamber is used to create the required vacuum environment. The workpiece is placed inside the chamber, and the electron gun generates and directs the high-velocity electron beam towards the workpiece. The vacuum chamber ensures the integrity of the process by eliminating any unwanted gas interactions.

Conclusion:
Electron Beam Machining (EBM) is a non-traditional machining process that requires a vacuum environment to achieve accurate and efficient material removal. The vacuum prevents electron scattering, oxidation, and contamination, ensuring high-quality machining.