1. Laser activated thyristor. Technical description.
System elements
Diffuser part is the key development, it allows to activate the thyristor with the light pulse delivered from the fibres distributed on the side, and to conduct the anode current in stacked thyristors configuration;
Complete electrical isolation;
Very short closure time;
Very low relative jitter in the closure of multiple devices;
Higher energetic efficiency comparing with electrical gating method;
Excellent scalability (kicker generator operating voltage);
BUT: Closure time is highly dependent on laser wavelength, therefore a specific source needs to be purchased/ hired
Laser test bench with the low inductance clamp
Beam Instrumentation Group (BE/ BI) laser setup b. 865
Thyristor in forward blocking state, VAK > 0
Gate and cathode layouts

2. Laser activated thyristor. Technical description.
Figure SCR Stack Assembly view
Commutation waveforms obtained with very stringent activation pulses of a low-cost thyristor.
Even 5 mm/kV can be expected + interconnections with external circuit
Figure Proof of concept configuration. View of stacked thyristor wafers overlapped with its diffusers

3. Laser activated SCR. Overview summary.
Goal
Thyratron replacement switch, power triggering IGBTs/ thyristors replacement.
Timescale to possible deployment
Medium term for new and consolidated generator switches and power triggers.
Gains w.r.t. present technology
Scalability;
Solid state switches (presently risk with single-source thyratron supplier);
Improved max di/dt ratings of the off shelf SCR devices;
Short closure times .
Possible deployment scope
Power triggers;
New or consolidated generators.
Ongoing activity domains - projects and present resource levels
Manufacturing of fused silica diffuser samples;
Possible collaboration with IXYS Westcode (UK);
0.2 Fellow ; 0.2 EDS support ; student missing
Present status and outlook
Illumination homogeneity measurement in BE Beam Instrumentation lab;
Proof of concept measurements with 1064 nm, fiber-coupled laser source with BE Beam Instrumentation lab;
Etching of thyristor electrodes witch CERN PCB Workshop - removing the metallisation in order to allow laser to penetrate into the structure.
Section Involvement
BTP EC X
EDS
KSC
PPE SE
Outside the group

4. Magnetic pulse compression. Technical description.
Increased performance in terms of current rise rate;
The stress applied to the switch can be reduced by using a pulse compression circuit;
Use of non-linear properties of a saturable magnetic core;
Usually one or more stages of discrete lumped LC low pass filters;
BUT : An additional-compression delay need to be taken into account. Moreover the leakage current during the compression interval (subsequent charge transfer from one LC lumped stage to another) – therefore two stages topology.
Prototype for evaluation in a power triggering circuit
Triggering Transformer primary current with two stages pulse compression circuit

5. Magnetic pulse compression. Overview summary.
Goal
Surge pulse generators current rise rate improvement without operating voltage increase.
Timescale to possible deployment
Medium term for new and consolidated surge generators and power triggers.
Gains w.r.t. present technology
Passive circuit element therefore better reliability expected;
Cheap and easy to dimension comparing witch traditional power electronics switches.
Possible deployment scope
Power triggers consolidation;
New or consolidated surge generators.
Ongoing activity domains - projects and present resource levels
Detailed investigation of delay times in triggering system of SBDS.
Present status and outlook
Pulse compression for SBDS5 triggering system with 400ns delay prototyped and tested. Tens of kA/us can b achieved.
Section Involvement
BTP EC X
EDS
KSC
PPE SE