20 T FIELD TARGET CALCULATION
Sources: outputs/20T-physics-audit.md; outputs/20T-magnet-recovery-audit.md
All assertions against audit/referee checkpoints passed.

1. PRESSURE CAPS (T_e = T_i = 100 keV, beta = 1)
+----------------------------+--------------+------+
| quantity                   | value        | unit |
+----------------------------+--------------+------+
| terminal n_D cap at 20 T   | 4.966835e+21 | m^-3 |
| Tier-2 n_D cap at 20 T     | 4.446585e+21 | m^-3 |
| Tier-2 pressure dilution D | 1.117000     | 1    |
| terminal B for n_D=1e21    | 8.974084     | T    |
| Tier-2 B for n_D=1e21      | 9.484550     | T    |
+----------------------------+--------------+------+

2. 19 T PROGRAM OPERATING FLOOR AND 20 T SELECTED EXTERNAL-FIELD TARGET (low-x_s relation at x_s=0.4 within its published domain; extrapolated from sub-keV data to 100 keV)
+-------+--------------+------------+--------------------+--------------+
| field | n_D (m^-3)   | tau_E (ms) | n_D tau_E (s m^-3) | target ratio |
+-------+--------------+------------+--------------------+--------------+
| 19 T  | 4.482569e+21 | 23.01688   | 1.031747e+20       | 1.031747     |
| 20 T  | 4.966835e+21 | 24.22829   | 1.203379e+20       | 1.203379     |
+-------+--------------+------------+--------------------+--------------+
+-----------------------------------------+--------------+-----------+
| derived quantity                        | value        | unit      |
+-----------------------------------------+--------------+-----------+
| low-x coefficient A                     | 5.156728e-13 | s m^(3/2) |
| density required for n tau_E=1e20       | 4.390136e+21 | m^-3      |
| stipulated-reference crossing at beta=1 | 18.803086    | T         |
| selected program operating floor        | 19           | T         |
| 20 T / crossing field ratio             | 1.063655     | ratio     |
| beta required at 20 T                   | 0.883890     | 1         |
+-----------------------------------------+--------------+-----------+

3. TERMINAL D-D BURN AND 1 m^3 TARGET YIELD AT 20 T
+------------------------------------+--------------+--------------+
| quantity                           | value        | unit         |
+------------------------------------+--------------+--------------+
| charged-only linear floor (1-eta)  | 3.469627e+19 | s m^-3       |
| charged-only exact floor (1/eta-1) | 3.492328e+19 | s m^-3       |
| unrecovered-bremsstrahlung factor  | 1.628930     | 1            |
| radiative linear floor             | 5.651779e+19 | s m^-3       |
| linear minimum burn                | 6.98559      | ms           |
| exact minimum burn                 | 7.03129      | ms           |
| radiative linear minimum burn      | 11.37904     | ms           |
| burn for n tau=1e20 target         | 20.13355     | ms           |
| 100 keV pT branch fraction         | 0.455564167  | 1            |
| branch-weighted total energy       | 3.616229     | MeV/reaction |
| branch-weighted charged energy     | 2.282361     | MeV/reaction |
| D-D reactions per pulse            | 1.223233e+19 | pulse^-1     |
| total fusion yield                 | 7.087211     | MJ/pulse     |
| charged yield                      | 4.473050     | MJ/pulse     |
+------------------------------------+--------------+--------------+

4. TIER-2 BURN AT 20 T
+---------------------------------+--------------+--------+
| quantity                        | value        | unit   |
+---------------------------------+--------------+--------+
| dilution-adjusted n_D tau floor | 1.100000e+19 | s m^-3 |
| pressure-consistent n_D         | 4.446585e+21 | m^-3   |
| minimum burn                    | 2.47381      | ms     |
| B_min for a 10 ms dwell         | 9.947480     | T      |
+---------------------------------+--------------+--------+

5. PRODUCT ORBITS AT 20 T (uniform local field, 90-degree birth)
+---------------------------+-------------+----------+---------------+------------+
| product                   | rho*B (m T) | rho (cm) | 0.23 m margin | 1 m margin |
+---------------------------+-------------+----------+---------------+------------+
| D-D proton, 3.02 MeV      | 0.25131     | 1.2565   | 18.304        | 79.583     |
| D-D triton, 1.01 MeV      | 0.25128     | 1.2564   | 18.306        | 79.592     |
| D-D helion, 0.82 MeV, Z=2 | 0.11320     | 0.5660   | 40.636        | 176.678    |
| D-T alpha, 3.52 MeV       | 0.27023     | 1.3512   | 17.023        | 74.011     |
| D-He3 proton, 14.67 MeV   | 0.55560     | 2.7780   | 8.279         | 35.997     |
| D-He3 alpha, 3.67 MeV     | 0.27593     | 1.3797   | 16.671        | 72.482     |
+---------------------------+-------------+----------+---------------+------------+

6. UNIFORM BORE ENERGY AND PRESSURE (V=3.185574951 m^3; annular fraction=0.874792899)
+-------+--------------+------------+----------------+--------------+
| field | u_B (MJ/m^3) | p_B (MPa)  | full bore (MJ) | annular (MJ) |
+-------+--------------+------------+----------------+--------------+
| 9 T   | 32.228876    | 32.228876  | 102.667500     | 89.812800    |
| 20 T  | 159.154943   | 159.154943 | 507.000000     | 443.520000   |
+-------+--------------+------------+----------------+--------------+
20 T / 9 T pressure-and-energy ratio: 4.93827160

7. CONDITIONAL BEAN LEDGERS (V_c=0.098017691 m^3, fixed J_c=3.000e+10 A/m^2)
+----------------------+------------+-------------+----------------+------------------+--------------------+----------------+
| ledger               | allocation | credit (MJ) | allocated (MJ) | W_allow (MJ/m^3) | d_max at 20 T (um) | % of 20 T bore |
+----------------------+------------+-------------+----------------+------------------+--------------------+----------------+
| fixed 0.90 MJ credit | one third  | 0.900000    | 0.300000       | 3.060672         | 7.65168            | 0.059172       |
| fixed 0.90 MJ credit | two thirds | 0.900000    | 0.600000       | 6.121344         | 15.30336           | 0.118343       |
| beta-scaled credit   | one third  | 4.444444    | 1.481481       | 15.114430        | 37.78607           | 0.292205       |
| beta-scaled credit   | two thirds | 4.444444    | 2.962963       | 30.228859        | 75.57215           | 0.584411       |
+----------------------+------------+-------------+----------------+------------------+--------------------+----------------+
Fixed-credit 9 T reference gates (one-third, two-thirds): 17.00373 um, 34.00747 um

8. REPETITION RATE FOR 10 kW AVERAGE OUTPUT
+-----------------------+-------------------+------------+------------+
| credited pulse energy | energy (MJ/pulse) | rate (mHz) | period (s) |
+-----------------------+-------------------+------------+------------+
| total fusion yield    | 7.087211          | 1.410992   | 708.721078 |
| charged yield         | 4.473050          | 2.235611   | 447.305034 |
+-----------------------+-------------------+------------+------------+

Conditions: beta=1 unless stated; the 0.9935 chain and Bean ledgers remain
conditional on 20 T requalification. Orbit radii are screening values, not
full-orbit confinement results.
