Add IonisationChamber block for tritium detection

src/pathsim_chem/tritium/__init__.py

@@ -2,4 +2,5 @@
 from .splitter import *
 from .bubbler import *
 from .glc import *
+from .ionisation_chamber import *
 # from .tcap import *

src/pathsim_chem/tritium/ionisation_chamber.py

@@ -0,0 +1,91 @@
+#########################################################################################
+##
+##                            Ionisation Chamber Block
+##
+#########################################################################################
+
+# IMPORTS ===============================================================================
+
+from pathsim.blocks.function import Function
+
+# BLOCKS ================================================================================
+
+class IonisationChamber(Function):
+    """Ionisation chamber for tritium detection.
+
+    Algebraic block that models a flow-through ionisation chamber. The sample
+    passes through unchanged while the chamber produces a signal proportional
+    to the tritium concentration, scaled by a detection efficiency.
+
+    Mathematical Formulation
+    -------------------------
+    The chamber receives a tritium flux and flow rate, computes the
+    concentration, and applies the detection efficiency:
+
+    .. math::
+
+        c = \\frac{\\Phi_{in}}{\\dot{V}}
+
+    .. math::
+
+        \\text{signal} = \\varepsilon(c) \\cdot c
+
+    .. math::
+
+        \\Phi_{out} = \\Phi_{in}
+
+    where :math:`\\varepsilon` is the detection efficiency (constant or
+    concentration-dependent).
+
+    Parameters
+    ----------
+    detection_efficiency : float or callable, optional
+        Constant efficiency factor or a function ``f(c) -> float`` that
+        returns the efficiency for a given concentration. Mutually
+        exclusive with *detection_threshold*.
+    detection_threshold : float, optional
+        If provided, the efficiency is a step function: 1 above the
+        threshold, 0 below. Mutually exclusive with *detection_efficiency*.
+    """
+
+    input_port_labels = {
+        "flux_in":   0,
+        "flow_rate": 1,
+    }
+
+    output_port_labels = {
+        "flux_out": 0,
+        "signal":   1,
+    }
+
+    def __init__(self, detection_efficiency=None, detection_threshold=None):
+
+        # input validation
+        if detection_efficiency is not None and detection_threshold is not None:
+            raise ValueError(
+                "Specify either 'detection_efficiency' or 'detection_threshold', not both"
+            )
+        if detection_efficiency is None and detection_threshold is None:
+            raise ValueError(
+                "One of 'detection_efficiency' or 'detection_threshold' must be provided"
+            )
+
+        if detection_threshold is not None:
+            self.detection_efficiency = lambda c: 1.0 if c >= detection_threshold else 0.0
+        else:
+            self.detection_efficiency = detection_efficiency
+
+        self.detection_threshold = detection_threshold
+
+        super().__init__(func=self._eval)
+
+    def _eval(self, flux_in, flow_rate):
+        concentration = flux_in / flow_rate if flow_rate > 0 else 0.0
+
+        eff = self.detection_efficiency
+        epsilon = eff(concentration) if callable(eff) else eff
+
+        signal = epsilon * concentration
+        flux_out = flux_in
+
+        return (flux_out, signal)

tests/tritium/test_ionisation_chamber.py

@@ -0,0 +1,117 @@
+########################################################################################
+##
+##                                  TESTS FOR
+##                     'tritium.ionisation_chamber.py'
+##
+########################################################################################
+
+# IMPORTS ==============================================================================
+
+import unittest
+
+from pathsim_chem.tritium import IonisationChamber
+
+
+# TESTS ================================================================================
+
+class TestIonisationChamber(unittest.TestCase):
+    """Test the IonisationChamber block."""
+
+    def test_init_constant_efficiency(self):
+        """Test initialization with constant detection efficiency."""
+        ic = IonisationChamber(detection_efficiency=0.8)
+        self.assertEqual(ic.detection_efficiency, 0.8)
+        self.assertIsNone(ic.detection_threshold)
+
+    def test_init_threshold(self):
+        """Test initialization with detection threshold."""
+        ic = IonisationChamber(detection_threshold=10.0)
+        self.assertEqual(ic.detection_threshold, 10.0)
+        self.assertTrue(callable(ic.detection_efficiency))
+
+    def test_init_callable_efficiency(self):
+        """Test initialization with callable detection efficiency."""
+        eff = lambda c: min(c / 100.0, 1.0)
+        ic = IonisationChamber(detection_efficiency=eff)
+        self.assertIs(ic.detection_efficiency, eff)
+
+    def test_init_validation_both(self):
+        """Providing both parameters should raise ValueError."""
+        with self.assertRaises(ValueError):
+            IonisationChamber(detection_efficiency=0.5, detection_threshold=10.0)
+
+    def test_init_validation_neither(self):
+        """Providing neither parameter should raise ValueError."""
+        with self.assertRaises(ValueError):
+            IonisationChamber()
+
+    def test_port_labels(self):
+        """Test port label definitions."""
+        self.assertEqual(IonisationChamber.input_port_labels["flux_in"], 0)
+        self.assertEqual(IonisationChamber.input_port_labels["flow_rate"], 1)
+        self.assertEqual(IonisationChamber.output_port_labels["flux_out"], 0)
+        self.assertEqual(IonisationChamber.output_port_labels["signal"], 1)
+
+    def test_passthrough(self):
+        """Sample flux passes through unchanged."""
+        ic = IonisationChamber(detection_efficiency=0.5)
+        ic.inputs[0] = 100.0  # flux_in
+        ic.inputs[1] = 10.0   # flow_rate
+        ic.update(None)
+
+        self.assertAlmostEqual(ic.outputs[0], 100.0)
+
+    def test_signal_constant_efficiency(self):
+        """Signal = efficiency * concentration."""
+        ic = IonisationChamber(detection_efficiency=0.8)
+        ic.inputs[0] = 200.0  # flux_in
+        ic.inputs[1] = 10.0   # flow_rate -> concentration = 20
+        ic.update(None)
+
+        self.assertAlmostEqual(ic.outputs[1], 0.8 * 20.0)
+
+    def test_signal_threshold_above(self):
+        """Above threshold, signal = concentration."""
+        ic = IonisationChamber(detection_threshold=5.0)
+        ic.inputs[0] = 100.0  # flux
+        ic.inputs[1] = 10.0   # flow -> concentration = 10 > 5
+        ic.update(None)
+
+        self.assertAlmostEqual(ic.outputs[1], 10.0)
+
+    def test_signal_threshold_below(self):
+        """Below threshold, signal = 0."""
+        ic = IonisationChamber(detection_threshold=50.0)
+        ic.inputs[0] = 100.0  # flux
+        ic.inputs[1] = 10.0   # flow -> concentration = 10 < 50
+        ic.update(None)
+
+        self.assertAlmostEqual(ic.outputs[1], 0.0)
+
+    def test_signal_callable_efficiency(self):
+        """Callable efficiency applied to concentration."""
+        # Linear ramp: efficiency = c / 100, capped at 1
+        eff = lambda c: min(c / 100.0, 1.0)
+        ic = IonisationChamber(detection_efficiency=eff)
+        ic.inputs[0] = 500.0  # flux
+        ic.inputs[1] = 10.0   # flow -> concentration = 50
+        ic.update(None)
+
+        # efficiency(50) = 0.5, signal = 0.5 * 50 = 25
+        self.assertAlmostEqual(ic.outputs[1], 25.0)
+
+    def test_zero_flow_rate(self):
+        """Zero flow rate should not crash, signal = 0."""
+        ic = IonisationChamber(detection_efficiency=1.0)
+        ic.inputs[0] = 100.0
+        ic.inputs[1] = 0.0
+        ic.update(None)
+
+        self.assertAlmostEqual(ic.outputs[0], 100.0)
+        self.assertAlmostEqual(ic.outputs[1], 0.0)
+
+
+# RUN TESTS LOCALLY ====================================================================
+
+if __name__ == '__main__':
+    unittest.main(verbosity=2)