The term High Energy Physics (HEP) covers a diverse field of specialised fast switching applications, medical, scientific and industrial linear accelerators (linacs) and very high voltage crowbars.
Thyratron or solid state switched modulators drive klystrons and magnetrons which provide electron and X-ray treatments. The thyratron operates intermittently in short 1 to 3 minute bursts with typical conditions of 25 kV, 1 kA, 5 µs pulses at up to 500 Hz and average currents up to 2 A. Rate of rise of current is modest at 20 kA/µs and jitter is not generally important.
Scientific linacs are similar to industrial linacs, except that average currents are generally less than 5 A. Jitter is more important and is generally specified at below 5ns. They are normally driven by high power klystrons and used to accelerate particle beams.
Thyratrons are used as protection devices for high power RF tubes such as super power klystrons and IOTs when used in HEP environments. Operating voltages range from 10 kV to 160 kV. The important characteristics of the thyratron in this application are its ability to switch on quickly and to carry the very long power supply follow-on fault currents. Tube type CX2708 has been specifically designed for the unique requirements of the crowbar protection circuitry of a UHF television transmitter powered by an IOT. The copper arc thyratron is a new development for low voltage (<40kV) crowbar applications and is a mercury-free ignitron replacement.
Crowbars for HEP are similar to those used in TV Broadcasting, but operating voltages can reach 160 kV. They are used to protect the klystrons and IOTs which accelerate further the particle beams in storage rings.
Thyratrons are used in fast-switched magnets which eject particles from their circular orbits in the various high energy physics machines around the world. Thyratrons for kickers operate over a wide voltage range from 20 kV to 85 kV, up to 10 kA and a few µs pulse lengths, but generally all require high rates of rise of current (~100 kA/µs) and low jitter figures (< 2 ns).