private void createDebris(){
                AssetManager assetManager = getApplication().getAssetManager();
                debris = new ParticleEmitter("Debris", ParticleMesh.Type.Triangle, 15 );
                debris.setSelectRandomImage(true);
                debris.setRandomAngle(true);
                debris.setRotateSpeed(FastMath.TWO_PI * 4);
                debris.setStartColor(new ColorRGBA(1f, 0.59f, 0.28f, 1.0f ));
                debris.setEndColor(new ColorRGBA(.5f, 0.5f, 0.5f, 0f));
                debris.setStartSize(.2f);
                debris.setEndSize(.2f);

//        debris.setShape(new EmitterSphereShape(Vector3f.ZERO, .05f));
                debris.setParticlesPerSec(0);
                debris.setGravity(0, 12f, 0);
                debris.setLowLife(1.4f);
                debris.setHighLife(1.5f);
                debris.getParticleInfluencer()
                        .setInitialVelocity(new Vector3f(0, 15, 0));
                debris.getParticleInfluencer().setVelocityVariation(.60f);
                debris.setImagesX(3);
                debris.setImagesY(3);
                Material mat = new Material(assetManager, "Common/MatDefs/Misc/Particle.j3md");
                mat.setTexture("Texture", assetManager.loadTexture("Effects/Explosion/Debris.png"));
                debris.setMaterial(mat);
                explosionEffect.attachChild(debris);
            }
This test's particle effects (using an explosion)
jme3-screenshot-tests/src/test/java/org/jmonkeyengine/screenshottests/effects/TestExplosionEffect.java