after all you can use a magnetic field as an acceleratorHaving worked with several linear accelerators i can vouch for that. However the placement and field strengths are very difficult calculations( sometimes Kentucky windage) to get it working correctly.
Now a vacumme tube based on a linear accelerator might be an interesting app. Then again you would have to step down from around five plus MEV and have shielding due to radiation.
(amp sounded fanstastic, but the listener died due to overexposure)
ron