# How fusion ignition works (the National Ignition Facility)

> A process map exported from forks.world (https://forks.world). Author: Brian. Source: https://forks.world/p/cmv0kpzty001djv06zuyply8v
> It describes who does what, in what order, and with which technology. Read the plain-language sections first; the JSON at the end is the exact, complete data.

## Summary

- 16 steps across 2 layers
- Persona: Scientists
- Technology / systems: 192 laser beams, The hohlraum, The fuel capsule

## Pain points

Where this process hurts, worst first:

- **A fizzle: not hot or dense enough** (How fusion ignition works (the National Ignition Facility); painful): Most shots do not ignite

## How to read this file

- A process is made of **layers**. The main layer is the top level; any step of kind `subprocess` opens a detail layer with its own lanes and steps.
- **Lanes** are either persona (people/roles) or technology (systems). Each step belongs to one lane; `using` lists tools a person uses for that step.
- Step kinds: `start`, `task`, `decision` (its arrows carry the answer as a label), `subprocess`, `end`.

## How fusion ignition works (the National Ignition Facility)

Lanes:
- 192 laser beams: technology / system (id `laser`)
- The hohlraum: technology / system (id `hohl`)
- The fuel capsule: technology / system (id `cap`)
- Scientists: person / role (id `team`)

Steps, in the order they run:

1. **Fire 192 laser beams into a gold cylinder** [start; 192 laser beams; id `f1`]
   - then It glows with X-rays
2. **It glows with X-rays** [task; The hohlraum; id `f2`]
   - then The X-rays squeeze a pellet of hydrogen fuel
3. **The X-rays squeeze a pellet of hydrogen fuel** [task; The fuel capsule; id `f3`]
   - then Crush it to a tiny, extremely dense and hot point
4. **Crush it to a tiny, extremely dense and hot point** [subprocess; The fuel capsule; id `f4`], opens the detail layer "The implosion"
   - then Do the nuclei get close enough to fuse?
5. **Do the nuclei get close enough to fuse?** [decision; The fuel capsule; id `f5`]
   - if "Yes" go to Fusion releases more energy than the hot spot lost; if "No" go to A fizzle: not hot or dense enough
6. **Fusion releases more energy than the hot spot lost** [task; The fuel capsule; id `f6`]
   - then Compare the energy out with the energy the lasers delivered
7. **Compare the energy out with the energy the lasers delivered** [task; Scientists; id `f7`]
   - then More out than in?
8. **More out than in?** [decision; Scientists; id `f8`]
   - if "Yes" go to December 2022: about 3.15 megajoules out for 2.05 in; if "Not yet" go to Improve and shoot again
9. **December 2022: about 3.15 megajoules out for 2.05 in** [task; Scientists; id `f9`]
   - then But making the laser light took far more power: this is not yet a power plant
10. **But making the laser light took far more power: this is not yet a power plant** [end; Scientists; id `f11`]
11. **Improve and shoot again** [task; Scientists; id `f10`]
   - then Fire 192 laser beams into a gold cylinder
12. **A fizzle: not hot or dense enough** [task; Scientists; id `f5a`] ⚠ PAIN POINT (painful): Most shots do not ignite
   - then Fire 192 laser beams into a gold cylinder

```mermaid
flowchart LR
  subgraph l_laser["192 laser beams"]
    n_f1(["Fire 192 laser beams into a gold cylinder"])
  end
  subgraph l_hohl["The hohlraum"]
    n_f2["It glows with X-rays"]
  end
  subgraph l_cap["The fuel capsule"]
    n_f3["The X-rays squeeze a pellet of hydrogen fuel"]
    n_f4[["Crush it to a tiny, extremely dense and hot point"]]
    n_f5{"Do the nuclei get close enough to fuse?"}
    n_f6["Fusion releases more energy than the hot spot lost"]
  end
  subgraph l_team["Scientists"]
    n_f5a["A fizzle: not hot or dense enough"]
    n_f7["Compare the energy out with the energy the lasers delivered"]
    n_f8{"More out than in?"}
    n_f10["Improve and shoot again"]
    n_f9["December 2022: about 3.15 megajoules out for 2.05 in"]
    n_f11(["But making the laser light took far more power: this is not yet a power plant"])
  end
  n_f1 --> n_f2
  n_f2 --> n_f3
  n_f3 --> n_f4
  n_f4 --> n_f5
  n_f5 -->|"Yes"| n_f6
  n_f5 -->|"No"| n_f5a
  n_f5a --> n_f1
  n_f6 --> n_f7
  n_f7 --> n_f8
  n_f8 -->|"Yes"| n_f9
  n_f8 -->|"Not yet"| n_f10
  n_f10 --> n_f1
  n_f9 --> n_f11
```

### The implosion (detail of step "Crush it to a tiny, extremely dense and hot point")

Lanes:
- The fuel capsule: technology / system (id `cap`)

Steps, in the order they run:

1. **A shell of ice and plastic compresses inward** [start; The fuel capsule; id `i1`]
   - then The center is heated to millions of degrees
2. **The center is heated to millions of degrees** [task; The fuel capsule; id `i2`]
   - then The central "hot spot" ignites
3. **The central "hot spot" ignites** [task; The fuel capsule; id `i3`]
   - then The burn spreads through the fuel
4. **The burn spreads through the fuel** [end; The fuel capsule; id `i4`]

```mermaid
flowchart LR
  subgraph l_cap["The fuel capsule"]
    n_i1(["A shell of ice and plastic compresses inward"])
    n_i2["The center is heated to millions of degrees"]
    n_i3["The central 'hot spot' ignites"]
    n_i4(["The burn spreads through the fuel"])
  end
  n_i1 --> n_i2
  n_i2 --> n_i3
  n_i3 --> n_i4
```

## Full data (JSON)

```json
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          "uses": [],
          "label": "More out than in?"
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          "label": "December 2022: about 3.15 megajoules out for 2.05 in"
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```