private void createSmokeTrail(){
                AssetManager assetManager = getApplication().getAssetManager();
                smoketrail = new ParticleEmitter("SmokeTrail", ParticleMesh.Type.Triangle, 22 );
                smoketrail.setStartColor(new ColorRGBA(1f, 0.8f, 0.36f, 1.0f ));
                smoketrail.setEndColor(new ColorRGBA(1f, 0.8f, 0.36f, 0f));
                smoketrail.setStartSize(.2f);
                smoketrail.setEndSize(1f);

                smoketrail.setFacingVelocity(true);
                smoketrail.setParticlesPerSec(0);
                smoketrail.setGravity(0, 1, 0);
                smoketrail.setLowLife(.4f);
                smoketrail.setHighLife(.5f);
                smoketrail.getParticleInfluencer()
                        .setInitialVelocity(new Vector3f(0, 12, 0));
                smoketrail.getParticleInfluencer().setVelocityVariation(1);
                smoketrail.setImagesX(1);
                smoketrail.setImagesY(3);
                Material mat = new Material(assetManager, "Common/MatDefs/Misc/Particle.j3md");
                mat.setTexture("Texture", assetManager.loadTexture("Effects/Explosion/smoketrail.png"));
                smoketrail.setMaterial(mat);
                explosionEffect.attachChild(smoketrail);
            }
This test's particle effects (using an explosion)
jme3-screenshot-tests/src/test/java/org/jmonkeyengine/screenshottests/effects/TestExplosionEffect.java