SASE Gain Length
Infer SASE exponential gain length from measured power growth.
Description
An exponential power-growth model infers gain length from observed SASE amplification.
An exponential power-growth model infers gain length from observed SASE amplification. The logarithm of power gain is the number of modeled gain lengths.1
Infer SASE exponential gain length from measured power growth.
When to use SASE Gain Length
Use this tool to infer SASE exponential gain length from measured power growth.
Prepare the optical measurements, geometry, fitted coefficients or caller-selected thresholds requested. Confirm wavelength, radius/diameter, pulse-width, angle and unit conventions before running the calculation.
How to use SASE Gain Length and understand its results
- Prepare the optical measurements, geometry, fitted coefficients or caller-selected thresholds requested. Confirm wavelength, radius/diameter, pulse-width, angle and unit conventions before running the calculation.
- Enter undulatorLengthMeters, initialPowerWatts, finalPowerWatts using the field table and calculation rules, then run the tool.
- Read powerGain, gainLengthMeters. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| undulatorLengthMeters | Measured amplification length (m) | number; minimum: 0 | Required |
| initialPowerWatts | Initial SASE power (W) | number; minimum: 0 | Required |
| finalPowerWatts | Final SASE power (W) | number; minimum: 0 | Required |
Enter nonnegative length, positive initial power and greater final power. Return gain and inferred gain length.
gain=final/initial; lengthScale=undulatorLength/ln(gain) Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| powerGain | Measured power gain | number; minimum: 0 |
| gainLengthMeters | Exponential gain length (m) | number; minimum: 0 |
{
"input": {
"undulatorLengthMeters": 2.302585092994046,
"initialPowerWatts": 1,
"finalPowerWatts": 10
},
"output": {
"powerGain": 10,
"gainLengthMeters": 1
}
}Limitations and assumptions
No saturation, shot-noise start-up or longitudinal gain variation is fitted.
Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.
Alternative or Complementary methods
Use Rare-Gas Pump Threshold: Compare absorbed pump power with a supplied rare-gas laser threshold. For a complementary task, use Random-Fiber Laser Threshold: Compare distributed random-fiber gain with supplied round-trip logarithmic loss.
References
-
SASE Gain Length — tool.io
Similar or alternative tools
- Rare-Gas Pump Threshold
Compare absorbed pump power with a supplied rare-gas laser threshold.
- Random-Fiber Laser Threshold
Compare distributed random-fiber gain with supplied round-trip logarithmic loss.